Journal articles: 'Vertical cylinder'

1

CHAPLIN, J. R., R. C. T. RAINEY, and R. W. YEMM. "Ringing of a vertical cylinder in waves." Journal of Fluid Mechanics 350 (November 10, 1997): 119–47. http://dx.doi.org/10.1017/s002211209700699x.

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This paper analyses the results of two series of experiments concerned with the response of a single vertical cylinder in the inertia regime in steep non-breaking waves. We recorded first the loading on a cylinder when it was held stationary, and secondly, its response in the same waves when it was pivoted just above the floor of the wave flume, and supported at the top by springs in the horizontal plane. Spring stiffnesses were set to achieve natural frequencies (measured in still water) in the range between 3 and 11 times the dominant wave frequency. The experiments were repeated with cylinders of three different diameters.Peak loading on stationary cylinders was found to exceed the predictions of a Morison model (based on kinematics computed from a numerical model of the measured waves), though improvements were achieved through the inclusion of slender-body terms. Measured ringing responses are generally in good agreement with those computed on a quasi-static basis from the measured loading history, but in some conditions, particularly at low frequency ratios, there is clearly some feedback from the motion to the excitation. Peak accelerations in the steepest waves are found to be limited approximately to those that would occur if the maximum loading were applied as a step change. Particular attention is given to a rapid cycle of loading that occurs after the crest has passed the cylinder's axis, and to images of the flow around the cylinder at the water surface.

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Rasin, Boris, Benjamin J. Lindsay, Xingchen Ye, Jeffrey S. Meth, Christopher B. Murray, Robert A. Riggleman, and Russell J. Composto. "Nanorod position and orientation in vertical cylinder block copolymer films." Soft Matter 16, no. 12 (2020): 3005–14. http://dx.doi.org/10.1039/d0sm00043d.

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Li, Shengli, Ruiqing Han, Pan Guo, Xidong Wang, and Yajie Chu. "Wind tunnel tests of aerodynamic interference effects on two iced vertical circular cylinders in a tandem arrangement." Fluid Dynamics Research 53, no. 6 (December 1, 2021): 065503. http://dx.doi.org/10.1088/1873-7005/ac3b36.

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Abstract The aerodynamic characteristics of the two iced vertical circular cylinders in a tandem arrangement, due to the shape change by icing, are complex, and lack systematical investigation. Therefore, a set of wind tunnel tests were carried out to study the aerodynamic characteristics of the leeward vertical cylinder, with ice shape, icing thickness, cylinder spacing, and icing relative position of cylinders varied in the subcritical Reynolds number range in this study. Results show that the icing thicknesses had a greater impact on the lift coefficients of D-shaped ice leeward cylinder at the same angle of attack. The aerodynamic characteristics of the iced leeward cylinder were stable when the ratio (L/D) of cylinder spacing was within the range of 4.8–6.2. The change of flow field should be considered in the stability analysis of two circular vertical cylinders. The drag coefficients of the iced leeward cylinder varied significantly due to the shielding effects, especially within the range of 9° attack angle and L< 6.2D. The results of this work can provide an experimental reference for future research on wind resistance of two circular cylindrical structures in engineering practice.

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Weggel, D. C., J. M. Roesset, and M. H. Kim. "Second-Order Vertical Diffraction Forces on Truncated Cylinders." Journal of Offshore Mechanics and Arctic Engineering 118, no. 4 (November 1, 1996): 259–66. http://dx.doi.org/10.1115/1.2833914.

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A number of parametric studies were performed on a series of single, truncated cylinders in deep water using second-order potential theory. The cylinders were subjected to a monochromatic incident wave field. Second-order vertical diffraction force components were computed and plotted to illustrate their variation with cylinder aspect ratio and incident wave frequency. These plots make it possible to obtain rough estimates of vertical second-order diffraction force quantities on cylindrical components without having to perform second-order diffraction theory computations. The double-frequency heave response amplitude operator RAO(2) for a freely floating truncated cylinder is presented as a function of cylinder aspect ratio and incident wave frequency. Calculations of the RAO(2) were made using the total double-frequency diffraction force and the first-order radiation coefficients evaluated at the double-frequency.

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Kano, Stefania Carvalho, Gerson Bonfante, Raquel Hussne, and Aline F. Siqueira. "Use of base metal casting alloys for implant framework: marginal accuracy analysis." Journal of Applied Oral Science 12, no. 4 (December 2004): 337–43. http://dx.doi.org/10.1590/s1678-77572004000400016.

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The original protocol for implant prosthesis recommends the use of a gold framework for acrylic and ceramic prosthesis. However, due to its high cost, the use of alternative alloys is desired. This study compares the marginal accuracy of pre-made cylinders versus plastic cylinders cast with two different base metal casting alloys. Five samples each of (1) plastic cylinder cast in cobalt-chromium alloy, (2) plastic cylinder cast in nickel-chromium alloy, and (3) silver-palladium pre-made cylinder (control) were examined for marginal accuracy according to: (A) vertical gap; (B) horizontal gap and (C) horizontal gap depth at the abutment/cylinder interface. Data were submitted to statistical analysis (ANOVA and Student-Newman Keuls, p<0.05). Mean values for vertical, horizontal and gap depth were 4.13µm, 14.5µm and 6.93µm for pre-made cylinder, 23.18µm, 33.2µm and 88µm for Ni-Cr cast cylinder and 25.6µm, 51.8µm and 114.54µm for Co-Cr cast cylinder. No statistically significant differences were found between cast groups (1 and 2), but significant better fit was obtained with pre-made metal cylinders when compared to cast cylinders with Ni-Cr and Co-Cr alloys, for all analyses.

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Masuda, K., and T. Nagai. "Nonlinear Wave Forces on a Pair of Vertical Cylinders." Journal of Offshore Mechanics and Arctic Engineering 113, no. 1 (February 1, 1991): 1–8. http://dx.doi.org/10.1115/1.2919891.

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The present paper is concerned with development of a powerful scheme for calculating nonlinear wave forces on a pair of vertical cylinders with arbitrary cross sections. The Laguerre integration method is applied and its convergence is confirmed in the cases of a single vertical cylinder and a twin circular cylinder. Further, the present method is compared with the method given by Eatock-Taylor and Hung [9], and then the computational times and those properties for a numerical calculation are investigated. The numerical results for maximum wave forces on the vertical cylinders obtained by the present method are compared with the experimental results, so that the usefulness is clarified.

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Isaacson, Michael, Thomas Mathai, and Carol Mihelcic. "Hydrodynamic coefficients of a vertical circular cylinder." Canadian Journal of Civil Engineering 17, no. 3 (June 1, 1990): 302–10. http://dx.doi.org/10.1139/l90-037.

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The added mass and the damping coefficient of a large surface-piercing circular cylinder extending to the seabed and undergoing horizontal oscillations are described. A closed-form solution to the corresponding linear radiation problem is obtained by the use of eigenfunction expansions. Attention is given to the vertical distribution of these coefficients and to their high-frequency asymptotic behaviour. Comparisons are made with experimental measurements. The application to typical offshore structures is discussed. Key words: added mass, cylinders, damping, hydrodynamics, ocean engineering.

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Wang, Yin, Lingling Wang, Hai Zhu, Hongwu Tang, and Gang Wei. "A Numerical Study of the Forces on Two Tandem Cylinders Exerted by Internal Solitary Waves." Mathematical Problems in Engineering 2016 (2016): 1–15. http://dx.doi.org/10.1155/2016/9086246.

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A three-dimensional numerical wave flume is employed to investigate the forces exerted by internal solitary waves (ISWs) on a pair of circular cylinders in tandem arrangement, using large-eddy simulation (LES) model. The effect of the centre-to-centre distance (L) ranging from 1.5 to 5 diameters (D) is studied for various ISWs amplitudes (ηa) in the two-layer fluid system. Vertical-averaged vorticity distribution and vertical-averaged pressure gradient distribution in each layer are presented to investigate the different hydrodynamic interference between cylinders and the ISWs forces on each cylinder at variousL. Furthermore, the force behaviors of the two cylinders are also compared with that of an isolated cylinder in the same environment. The interaction between the two piles occurs in both layers, and it is found that, for1.5≤L/D<3.5, strong mutual interference appears between two cylinders; for3.5≤L/D<5, the two cylinders continue to influence each other in a weak-interference state; forL/D≥5, the interaction gradually decreases into a noninteracting state. This paper tries to provide some references to structural arrangement of double-cylinder structure and grouped-cylinder structure in stratified flow environment.

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9

Karim, F., B. Farouk, and I. Namer. "Natural Convection Heat Transfer From a Horizontal Cylinder Between Vertical Confining Adiabatic Walls." Journal of Heat Transfer 108, no. 2 (May 1, 1986): 291–98. http://dx.doi.org/10.1115/1.3246918.

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This paper reports an experimental study of natural convection heat transfer from a horizontal isothermal cylinder between vertical adiabatic walls. Some of the industrial applications of this problem are cooling and casing design of electronic equipment, nuclear reactor safety, and heat extraction from solar thermal storage devices. Heat transfer from 3.81 cm and 2.54 cm diameter cylinders was determined by measuring the electric power supplied to the heater, which was placed inside the cylinders, and correcting for radiation and end losses. Average Nusselt numbers were determined for a Rayleigh number range of 2 × 103 to 3 × 105 and wall spacing to cylinder diameter ratios of 1.5, 2, 3, 4, 6, 8, 10, 12, and ∞. It was found that the confinement of a heated horizontal cylinder by adiabatic walls enhances the heat transfer from the cylinder continuously. This effect is more pronounced at low Rayleigh numbers. A maximum relative enhancement of 45 percent was obtained over the range of experimental conditions studied. Schlieren and flow visualization studies were conducted at selected values of Rayleigh number and wall spacing to cylinder diameter ratios to further explain the heat transfer characteristics and the associated flow physics of the present problem.

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10

Al-Alusi, T. R., and D. J. Bushnell. "An Experimental Study of Free Convection Heat Transfer From an Array of Horizontal Cylinders Parallel to a Vertical Wall." Journal of Heat Transfer 114, no. 2 (May 1, 1992): 394–400. http://dx.doi.org/10.1115/1.2911287.

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An experimental investigation of heat transfer from an array of three horizontal cylinders aligned vertically parallel to a single wall is presented. Three different cylinder center-to-center spacings for the array cylinders were examined, CC= 1.5D, 2D, and 4D. The wall-array spacings were varied from 0.081D to infinity. The cylinders were placed in a still air medium at atmospheric pressure and maintained at constant heat flux. Modified Rayleigh number, based on the diameter of the cylinders, ranged from 6.2 × 104 to 1.2 × 106. Results indicate that heat transfer is generally enhanced, but for some wall spacing to cylinder configurations the heat transfer can be minimally decreased. For cases where the heat transfer was enhanced the top cylinder in the array was observed to have the highest enhancement (22 percent) and the lowest cylinder was enhanced the least (5 percent). Flow visualization studies showed that the wall generated a chimney effect between the wall and the cylinders.

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11

Boughezala, Hamad Ahmed, Said Bouabdallah, and Ali Boukhari. "Forced Convection inside a Vertical Circular Cylinder with an Inner Coaxial Rectangular Cylinder." Defect and Diffusion Forum 406 (January 2021): 25–35. http://dx.doi.org/10.4028/www.scientific.net/ddf.406.25.

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In this work, we performed a numerical simulation of laminar forced convection and, in an annular space inside a vertical circular cylinder with an inner coaxial rectangular cylinder having an aspect ratio (height/radius) γ=2, filled with a liquid metal (Pr = 0.0023). Six annular gaps R =0.9, 0.8, 0.7, 0.6, 0.5 and 0.4 were studied. The governing equations are solved using the ANSYS Fluent code which is based on the finite volume method. SIMPLE algorithm is employed for the pressure-velocity coupled momentum equations. Two cases of the rotating parts of the cylinders are investigated and the effect of Reynolds number on the flow are examined. The obtained results of the forced convection show that the increase of the Reynolds number Re affects straightly on the structure of the flow wherever the velocity field are destabilized and the strongest stabilization of the velocity field occurs when the flow generated by the rotating of the circular cylinder and the rectangular cylinder.Keywords: forced convection, annular gap, circular cylinder, rectangular cylinder, co-rotating.

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Boughezala, Hamad Ahmed, Said Bouabdallah, and Ali Boukhari. "Forced Convection inside a Vertical Circular Cylinder with an Inner Coaxial Rectangular Cylinder." Defect and Diffusion Forum 406 (January 2021): 25–35. http://dx.doi.org/10.4028/www.scientific.net/ddf.406.25.

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In this work, we performed a numerical simulation of laminar forced convection and, in an annular space inside a vertical circular cylinder with an inner coaxial rectangular cylinder having an aspect ratio (height/radius) γ=2, filled with a liquid metal (Pr = 0.0023). Six annular gaps R =0.9, 0.8, 0.7, 0.6, 0.5 and 0.4 were studied. The governing equations are solved using the ANSYS Fluent code which is based on the finite volume method. SIMPLE algorithm is employed for the pressure-velocity coupled momentum equations. Two cases of the rotating parts of the cylinders are investigated and the effect of Reynolds number on the flow are examined. The obtained results of the forced convection show that the increase of the Reynolds number Re affects straightly on the structure of the flow wherever the velocity field are destabilized and the strongest stabilization of the velocity field occurs when the flow generated by the rotating of the circular cylinder and the rectangular cylinder.Keywords: forced convection, annular gap, circular cylinder, rectangular cylinder, co-rotating.

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13

Isaacson, M., and T. Mathai. "Hydrodynamic Coefficients of Vertical Cylinders of Arbitrary Section." Journal of Offshore Mechanics and Arctic Engineering 113, no. 2 (May 1, 1991): 109–16. http://dx.doi.org/10.1115/1.2919906.

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The calculation of added masses and damping coefficients of a large surface-piercing vertical cylinder of arbitrary section extending to the seabed and undergoing harmonic oscillations is described. The linear radiation problem in three dimensions is reduced to a series of two-dimensional problems in the horizontal plane by the use of appropriate eigenfunctions that represent the variation of the velocity potential in the vertical direction. Each of these is solved by a numerical approach based on the method of integral equations. Comparisons are made with an analytic solution available for the case of a circular cylinder. Results are also provided for square cylinders, and the application to typical offshore structures subject to base motions is discussed.

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14

Jha, Basant K., and Michael O. Oni. "Transient natural convection flow between vertical concentric cylinders heated/cooled asymmetrically." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 232, no. 7 (February 19, 2018): 926–39. http://dx.doi.org/10.1177/0957650918758743.

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This paper investigates the impact of asymmetric heating or cooling of cylinder surfaces on transient natural convection flow in between vertical concentric cylinders. The outer surface of inner cylinder is assumed to be heated with temperature greater than the cooled inner surface of the outer cylinder. Closed form expressions are obtained by using the well-known Laplace transform technique to solve the governing partial differential equations in Laplace domain, whereas the Riemann-sum approximation is used to invert to time domain. Results show that the role of buoyancy force distribution parameter is to increase temperature, velocity, skin-friction and volume flow rate for both air and water. Further, reverse flow formation can be controlled by using suitable buoyancy force distribution parameter.

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15

Roy, S., and D. Anilkumar. "Unsteady Mixed Convection From a Moving Vertical Slender Cylinder." Journal of Heat Transfer 128, no. 4 (November 22, 2005): 368–73. http://dx.doi.org/10.1115/1.2165206.

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A general analysis has been developed to study flow and heat transfer characteristics of an unsteady laminar mixed convection on a continuously moving vertical slender cylinder with surface mass transfer, where the slender cylinder is inline with the flow. The unsteadiness is introduced by the time-dependent velocity of the slender cylinder as well as that of the free stream. The calculations of momentum and heat transfer on slender cylinders considered the transverse curvature effect, especially in applications such as wire and fiber drawing, where accurate predictions are required. The governing boundary layer equations along with the boundary conditions are first cast into a dimensionless form by a nonsimilar transformation, and the resulting system of nonlinear coupled partial differential equations is then solved by an implicit finite difference scheme in combination with the quasi-linearization technique. Numerical results are presented for the skin friction coefficient and Nusselt number. The effects of various parameters on the velocity and temperature profiles are also reported here.

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Hayashi, Kenjirou, and Toshiyuki Shigemura. "UNSTEADY FLOW AROUND A VERTICAL CIRCULAR CYLINDER IN A WAVE." Coastal Engineering Proceedings 1, no. 21 (January 29, 1988): 68. http://dx.doi.org/10.9753/icce.v21.68.

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The unsteady characteristics of flow around a vertical circular cylinder in a typical wave, under which the lift force acting on it is very stable and has a frequency which is twice that of the incident wave, have been investigated experimentally. The relationship between the fluctuating flow velocities near the boundary layer separation points and the lift force acting on a sectional part of the cylinder has been understood quantitatively. To clarify the region where the appearance of stable lift force occurs, the long time records of lift forces acting on vertical cylinders in waves are also performed.

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Guo, Wenfeng, Yingwei Zhang, Yan Li, Kotaro Tagawa, and Bin Zhao. "A Wind Tunnel Experimental Study on the Icing Characteristics of a Cylinder Rotating around a Vertical Axis." Applied Sciences 11, no. 21 (November 5, 2021): 10383. http://dx.doi.org/10.3390/app112110383.

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Rotating machinery in cold and humid regions is prone to icing. For exploring the characteristics of icing on objects rotating around a vertical axis, such as vertical axis wind turbines (VAWT), a cylinder rotating around the vertical axis was selected as the research object in this study. Three cylinders with different diameters were selected, and icing tests carried out under different tip speed ratios (TSR) in a self-built icing wind tunnel. The icing characteristics were quantitatively analyzed using characteristic parameters, including the icing area, the dimensionless icing area, the stagnation point thickness and the dimensionless stagnation point thickness. The dimensionless stagnation point thickness decreased with increases in the diameter of the cylinder. The icing limit decreased with an increase in the rotational speed of the cylinder, and reached 50% under the high TSR condition. Various icing characteristics were also analyzed for two rotation modes: rotation around the vertical axis and around the horizontal axis. The research findings in the present study lay the theoretical and experimental foundations for exploring VAWT icing in depth.

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Xu, Wanhai, Wenqi Qin, and Yan Lu. "Application of Control Rods for Passively Suppressing Cross-Flow VIV of an Inclined Flexible Cylinder." Shock and Vibration 2018 (November 5, 2018): 1–13. http://dx.doi.org/10.1155/2018/8365726.

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Laboratory experiments were conducted to investigate the cross-flow (CF) vortex-induced vibration (VIV) suppression effectiveness of an inclined flexible cylinder by using control rods. 4 control rods with a diameter of 0.25D (where D is the diameter of the main cylinder) and outer wall distance between the control rod and the main cylinder of 0.50D were attached to the main cylinder. The uniform flow was simulated by towing the cylinder models along a water tank. The corresponding flow velocity ranged from 0.05 to 1.00 m/s with an interval of 0.05 m/s. Two inclination angle cases (a = 0° and 45°) were selected in the experiment. The inclination angle a referred to the angle between the main cylinder axis and the plane orthogonal to the oncoming flow. The experimental results indicate that the control rods can effectively mitigate the CF VIV responses, such as the bending strain, displacement amplitude, dominant frequency, and dominant mode, of both the vertical (a = 0°) and inclined (a = 45°) flexible cylinders. The suppression effectiveness of the control rods on the 45° inclined cylinder is as good as that on the vertical cylinder, and the average suppressing efficiency of the control rods is even better on the 45° inclined cylinder.

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Hu, H. R., C. Zhang, and X. Wang. "Numerical acoustic simulation of flow around circular cylinders based on Lattice Boltzmann method and Ffowcs Williams-Hawkings acoustic equation." International Journal of Computational Materials Science and Engineering 07, no. 01n02 (June 2018): 1850010. http://dx.doi.org/10.1142/s2047684118500100.

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Based on the GPU acceleration technique, Lattice Boltzmann method (LBM) and Ffowcs Williams-Hawkings (FW-H) acoustic equation are adopted to simulate the noise generated by flow around fixed and rotating circular cylinders when Reynolds number (Re) is 200. The results show that the sound pressure level has a peak in the vertical direction and it is higher than that in the streamwise direction. The maximum sound pressure level is significantly reduced when the cylinder rotates due to the suppression of vortex shedding compared to the case of a fixed cylinder. For tandem cylinders, the maximum sound pressure level in the vertical direction increases as the spacing ratio increases, and for parallel cylinders, it decreases as the spacing ratio increases. In addition, when using graphic processing unit (GPU), the computational efficiency is improved greatly and the speed-up reaches nearly 100.

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Wang, Zhuoran, Gang Hu, Dongqin Zhang, Bubryur Kim, Feng Xu, and Yiqing Xiao. "Aerodynamic Characteristics of a Square Cylinder with Vertical-Axis Wind Turbines at Corners." Applied Sciences 12, no. 7 (March 30, 2022): 3515. http://dx.doi.org/10.3390/app12073515.

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A preliminary study is carried out to investigate the aerodynamic characteristics of a square cylinder with Savonius wind turbines and to explain the reason why this kind of structure can suppress wind-induced vibrations. A series of computational fluid dynamics simulations are performed for the square cylinders with stationary and rotating wind turbines at the cylinder corners. The turbine orientation and the turbine rotation speed are two key factors that affect aerodynamic characteristics of the cylinder for the stationary and rotating turbine cases, respectively. The numerical simulation results show that the presence of either the stationary or rotating wind turbines has a significant effect on wind forces acting on the square cylinder. For the stationary wind turbine cases, the mean drag and fluctuating lift coefficients decrease by 37.7% and 90.7%, respectively, when the turbine orientation angle is 45°. For the rotating wind turbine cases, the mean drag and fluctuating lift coefficients decrease by 34.2% and 86.0%, respectively, when the rotation speed is 0.2 times of vortex shedding frequency. Wind turbines installed at the corners of the square cylinder not only enhance structural safety but also exploit wind energy simultaneously.

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MALENICA, š., R. EATOCK TAYLOR, and J. B. HUANG. "Second-order water wave diffraction by an array of vertical cylinders." Journal of Fluid Mechanics 390 (July 10, 1999): 349–73. http://dx.doi.org/10.1017/s0022112099005273.

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The problem of second-order water wave diffraction of an incident monochromatic wave field by an array of bottom-mounted circular cylinders is solved by a semi-analytical approach. The solution for the second-order potential is obtained by combining eigenfunction expansions with an integral representation. Unlike the indirect approach for second-order forces (Lighthill 1979; Molin 1979), this approach gives complete information about local flow characteristics (pressure, velocities, wave elevation, etc.) thus providing a basis for solving the third-order problem. The results obtained are compared with other published data, and new detailed results, useful for benchmarking purposes, are given. Finally the influences of wave incidence, cylinder radius and cylinder configuration are considered. This leads to the suggestion that there exists a near-trapping phenomenon for the second-order wave in an array of cylinders, at half the wave frequency at which the corresponding linear near-trapped mode occurs.

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Masuda, K., W. Kato, and H. Ishizuka. "Second-Order Diffraction Loads on Plural Vertical Cylinder With Arbitrary Cross Sections." Journal of Offshore Mechanics and Arctic Engineering 109, no. 4 (November 1, 1987): 314–19. http://dx.doi.org/10.1115/1.3257026.

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The purpose of the present study is development of a powerful numerical method for calculating second-order diffraction loads on plural vertical cylinder with arbitrary cross sections. According to the present method, second-order wave force can be obtained from a linear radiation potential without solving second-order boundary value problem. The boundary value problem for the radiation potential is solved with the hybrid boundary element method. The computations for circular and rectangular cylinders were carried out and compared with the experiments. In addition, second-order wave forces on twin circular cylinder are calculated with the present method.

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Nishikawa, Sinzo. "Heat Transfer in Vertical Concentric Cylinders with an Inner Rotating Cylinder." KAGAKU KOGAKU RONBUNSHU 18, no. 2 (1992): 253–56. http://dx.doi.org/10.1252/kakoronbunshu.18.253.

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Hadjadj, Ahmed, and Seghir Maamir. "Laminar Mixed Convection in Two Concentric Vertical Cylinders." International Journal of Chemoinformatics and Chemical Engineering 5, no. 1 (January 2016): 24–43. http://dx.doi.org/10.4018/ijcce.2016010103.

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The flow patterns and heat transfer have been studied numerically for contained air in the space formed by two vertical concentric cylinders. The inner cylinder rotates about its vertical axis and the outer cylinder is kept stationary. This geometry simulates, for example, the gaps at the ends of the rotor of vertical electric motors. The results facilitate the thermal design of such devices. The governing equations for velocity and temperature are solved by finite volume techniques in which the SIMPLE algorithm is incorporated. Results are presented for a range of Reynolds numbers (Re) and for various values of aspect ratio. It has been found that for high values of Re, the flow is dominated by centrifugal forces whereas for low values of Re the flow is dominated by gravitational buoyancy. To facilitate the use of results for design, some correlations were developed which represent the heat transfer coefficient as a continuous function of the investigated independents parameters.

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Disibuyuk, Nazile B., Oguz Yilmaz, Alexander Korobkin, and Tatyana Khabakhpasheva. "An Iterative Method for Interaction of Hydro-Elastic Waves with Several Vertical Cylinders of Circular Cross-Sections." Journal of Marine Science and Engineering 10, no. 6 (May 25, 2022): 723. http://dx.doi.org/10.3390/jmse10060723.

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The problem of ice loads acting on multiple vertical cylinders of circular cross-sections frozen in an ice cover of infinite extent is studied. The loads are caused by a flexural-gravity wave propagating in the ice cover towards the rigid bottom-mounted cylinders. This is a three-dimensional linearized problem of hydroelasticity with finite water depth. The flow under the ice is potential and incompressible. The problem is solved by the vertical mode method combined with an iterative method. The velocity potential is written with respect to each cylinder and is expanded into the Fourier series. The algorithm of the problem solving is reduced to calculations of the Fourier coefficients of the velocity potential. Numerical results for the forces acting on four circular cylinders are presented for different ice thicknesses, incident wave angles and cylinder spacing. The obtained wave forces are compared with the results by others. Good agreement is reported.

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Kriebel, David L. "NONLINEAR DIFFRACTION BY A VERTICAL CYLINDER." Coastal Engineering Proceedings 1, no. 21 (January 29, 1988): 1. http://dx.doi.org/10.9753/icce.v21.1.

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A theoretical solution is developed for the interaction of second-order Stokes waves with a large vertical circular cylinder in water of finite depth. The solution is obtained in terms of the velocity potential such that any kinematic or dynamic quantity of interest may be derived, consistent to the second perturbation order. In this study, the second-order wave field around the cylinder is determined, showing the modification of the incident Stokes waves by wave-wave and wave-structure interactions, both in the reflection-dominated up-wave region and in the diffraction-dominated down-wave region. The theory is then compared to experimental data for wave runup and rundown amplitudes on the cylinder as well as for wave crest and trough envelopes in the up-wave and down-wave regions.

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Ferguson, Frank T., and Lembit U. Lilleleht. "Thermovibrational convection in a vertical cylinder." International Journal of Heat and Mass Transfer 39, no. 14 (September 1996): 2895–906. http://dx.doi.org/10.1016/0017-9310(95)00384-3.

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Silva-Leon, Jorge, and Andrea Cioncolini. "Effect of Inclination on Vortex Shedding Frequency Behind a Bent Cylinder: An Experimental Study." Fluids 4, no. 2 (May 31, 2019): 100. http://dx.doi.org/10.3390/fluids4020100.

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This paper presents experimental results on the vortex shedding frequency measured behind a bent cylinder. Experiments were conducted in a wind tunnel covering Reynolds numbers between 50 and 500, a range of interest for flow sensing, flow control, and energy harvesting applications. The bent cylinder comprised a vertical leg always oriented at normal incidence with respect to the free-stream flow, and an inclined leg whose inclination was varied during the tests between 90° and 15°. The bent cylinder was oriented in the wind tunnel with the vertical leg upstream and the inclined leg downstream, and the vortex shedding frequency was measured with hot-wire anemometry at several locations behind the inclined leg. The present bent cylinder design improves upon those previously considered by providing a finer control on the upstream boundary condition acting upon the inclined leg, which in the present design is not affected by the yaw angle of the inclined leg. With the exception of free-end effects, only noticeable for certain inclinations and Reynolds number values, inclination effects were surprisingly not observed, and the frequency of vortex shedding measured behind the inclined leg of the bent cylinder was consistent (within a few percent) with the cross-flow vortex shedding frequency at the same flow velocity. The present results corroborate and significantly extend the limited observations on bent cylinders available in the literature, further highlighting the importance of the upstream boundary condition on the vortex shedding process with inclined cylinders.

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Cianfrini, Marta, Massimo Corcione, Alessandro Quintino, and Vincenzo Andrea Spena. "Laminar natural convection from a vertical array of horizontal heated cylinders inside a water-filled rectangular enclosure cooled at sides." International Journal of Numerical Methods for Heat & Fluid Flow 30, no. 5 (July 11, 2019): 2607–23. http://dx.doi.org/10.1108/hff-04-2019-0373.

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Purpose The purpose of this study is to investigate numerically the laminar natural convection from a pair of horizontal heated cylinders, set one above the other, inside a water-filled rectangular enclosure cooled at sides, with perfectly insulated top and bottom walls, through a control-volume formulation of the finite-difference method, with the main aim to evaluate the effects of the center-to-center cylinder spacing, the size of the cavity and the temperature difference imposed between the cylinders and the cavity sides. Design/methodology/approach The system of the conservation equations of the mass, momentum and energy, expressed in dimensionless form, is solved by a specifically developed computer code based on the SIMPLE-C algorithm for the pressure-velocity coupling. Numerical simulations are executed for different values of the Rayleigh number based on the cylinder diameter, as well as the center-to-center cylinder spacing and the width of the cavity normalized by the cylinder diameter. Findings The main results obtained may be summarized as follows: the existence of an optimum cylinder spacing for maximum heat transfer rate is found at any investigated Rayleigh number; as a consequence of the downstream confinement, a periodic flow arises at sufficiently high Rayleigh numbers; the amplitude of oscillation of the periodic heat transfer performance of the cylinder array decreases as the cylinder spacing is increased and the cavity width is decreased, whereas the frequency of oscillations remains almost the same; at very small cavity widths, a transition from the typical two-cell to a four-cell flow pattern occurs. Originality/value The computational code used in the present study incorporates an original composite polar/Cartesian discretization grid scheme.

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30

Modarres-Sadeghi, Y., M. P. Païdoussis, C. Semler, and E. Grinevich. "Experiments on vertical slender flexible cylinders clamped at both ends and subjected to axial flow." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 366, no. 1868 (November 5, 2007): 1275–96. http://dx.doi.org/10.1098/rsta.2007.2131.

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Three series of experiments were conducted on vertical clamped–clamped cylinders in order to observe experimentally the dynamical behaviour of the system, and the results are compared with theoretical predictions. In the first series of experiments, the downstream end of the clamped–clamped cylinder was free to slide axially, while in the second, the downstream end was fixed; the influence of externally applied axial compression was also studied in this series of experiments. The third series of experiments was similar to the second, except that a considerably more slender, hollow cylinder was used. In these experiments, the cylinder lost stability by divergence at a sufficiently high flow velocity and the amplitude of buckling increased thereafter. At higher flow velocities, the cylinder lost stability by flutter (attainable only in the third series of experiments), confirming experimentally the existence of a post-divergence oscillatory instability, which was previously predicted by both linear and nonlinear theory. Good quantitative agreement is obtained between theory and experiment for the amplitude of buckling, and for the critical flow velocities.

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Çalisal, S. M., and T. Sabuncu. "A Study of a Heaving Vertical Cylinder in a Towing Tank." Journal of Ship Research 33, no. 02 (June 1, 1989): 107–14. http://dx.doi.org/10.5957/jsr.1989.33.2.107.

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The effects of tank walls on experimentally measured hydrodynamic coefficients are of concern to researchers. In this numerical study of heaving vertical cylinders in a towing tank, the nonresonant, linear potential flow around a heaving cylinder in a towing tank has been formulated. The method used is based on a matching technique and on Graf's addition theorem. The calculations suggest that "blockage" or "wall effect" is more pronounced in shallow water tanks. A resonant frequency ω, corresponds to the frequency of a wave with a wave length equal to the width of the tank. For frequencies higher than ωr hydrodynamic coefficients are very close to infinite domain values for large values of the ratio of the tank beam to the cylinder radius. For frequencies less than ωr blockage correction to the hydrodynamic coefficients is necessary.

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32

Brocklehurst, Paul, Alexander Korobkin, and Emilian I. Părău. "Hydroelastic wave diffraction by a vertical cylinder." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 369, no. 1947 (July 28, 2011): 2832–51. http://dx.doi.org/10.1098/rsta.2011.0110.

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A linear three-dimensional problem of hydroelastic wave diffraction by a bottom-mounted circular cylinder is analysed. The fluid is of finite depth and is covered by an ice sheet, which is clamped to the cylinder surface. The ice stretches from the cylinder to infinity in all lateral directions. The hydroelastic behaviour of the ice sheet is described by linear elastic plate theory, and the fluid flow by a potential flow model. The two-dimensional incident wave is regular and has small amplitude. An analytical solution of the coupled problem of hydroelasticity is found by using a Weber transform. We determine the ice deflection and the vertical and horizontal forces acting on the cylinder and analyse the strain in the ice sheet caused by the incident wave.

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Haritos, N., and H. Yang. "An Investigation of Hydrodynamic Damping of Vertical Bottom-Pivoted Cylinders." Journal of Offshore Mechanics and Arctic Engineering 114, no. 4 (November 1, 1992): 257–63. http://dx.doi.org/10.1115/1.2919978.

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This paper investigates theoretical formulations for the radiation and “drag”-dependent hydrodynamic damping mechanisms for vertical bottom-pivoted cylinders under excitation by irregular uni-directional Pierson-Moskowitz waves. Experimental verification of the coexistence of these two forms of hydrodynamic damping is provided from the results of a program of research being conducted in the Michell Laboratory at the University of Melbourne on a wide range of cylinder test conditions.

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34

Xu, Li, Song Gao, Da Zheng Wang, and N. Barltrop. "Shallow Water Breaking Wave Loads on Vertical Cylinders." Advanced Materials Research 694-697 (May 2013): 659–64. http://dx.doi.org/10.4028/www.scientific.net/amr.694-697.659.

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Many offshore and harbor structures are composed of cylindrical members. In this paper, the special case of shoaling breaking wave loads on a vertical cylinder is investigated in a tank. A segmented cylinder model with outer diameter of 0.204m and total height of 1m was built and tested. Also a 1:20 slope ramp was constructed in the tank to provide the shoaling effect. During the experiments the total force on each segment of the cylinder was measured and the water surface elevations at the cylinder and in deep water were also recorded. Studies on wave shapes and wave loads are presented here.

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Kuila, Asim, Subhasish Das, and Asis Mazumdar. "A Comparative Analysis of Flow Fields around a Composite Hydrokinetic Device." Applied Mechanics and Materials 897 (April 2020): 173–78. http://dx.doi.org/10.4028/www.scientific.net/amm.897.173.

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. The flow pattern on the combined effect of a horizontal cylinder and a vertical plate is observed and analysed in this experimental study. The experiment was conducted with a 4 cm outer diameter cylinder arranged horizontally across flow above 2 cm from the bed and a vertical plate of 5 cm placed 9 cm downstream from cylinder surface reference as tilting flume bed surface. The water depth was maintained at 17 cm through a constant discharge of 35 lps in a re-circulating flume. Acoustic Doppler Velocimeter (ADV) was used to store the velocity fluctuation of velocity components and further used as a pictorial frame to understand the turbulence and the turbulent kinetic energy around the cylinder, plate and in between the cylinder - vertical plate. From the pictorial contour diagrams drawn, the velocity vector represents the flow feature over the cylinder and it is found that a horseshoe vortex, developed upstream of the plate, does effect on turbulent kinetic energy formed in between cylinder and vertical plate. The observation and obtained results from present study is compared with a 5 cm horizontal cylinder above 2 cm from the bed and a plate situated on 5.5 cm from cylinder curvature towards downstream.

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Su, Pei Qun, and Zhi Hui Deng. "Analysis of the Opening Characteristic of Hydraulic Control One-Way Valve in Vertical Hydraulic Cylinder Balance Circuits." Applied Mechanics and Materials 318 (May 2013): 15–20. http://dx.doi.org/10.4028/www.scientific.net/amm.318.15.

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Hydraulic control one-way valve as the retaining element of vertical hydraulic cylinder, often is due to improper application to produce large opening pressure, not unlocking, vibration, noise etc.fault. This paper analyses two vertical hydraulic balance circuit, one makes use of the one-way throttle valve and another is not,calculates the necessary condition and opening pressure of hydraulic control one-way valve reverse opening, obtains the opening characteristic of hydraulic control one-way valve in vertical balancing circuit, acquires the relationship of the reverse opening pressure with hydraulic cylinder balance pressure, hydraulic cylinder speed ratio, hydraulic control one-way valve structural parameters. Lastly, how to correctly use the hydraulic control one-way valve is discussed in the vertical hydraulic cylinder balanced circuit.

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Kudeih, Mohamed, Andrew Cornett, and Ioan Nistor. "AN EXPERIMENTAL STUDY OF WAVE AND CURRENT-INDUCED FORCES ON A COMPACT LINEAR ARRAY OF VERTICAL CYLINDERS IN SHALLOW WATER." Coastal Engineering Proceedings 1, no. 32 (February 2, 2011): 54. http://dx.doi.org/10.9753/icce.v32.waves.54.

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Arrays of vertical cylinders are essential components of many coastal structures, such as bridge piers, platform legs, and pile breakwaters. Thus, estimating the maximum wave and current-induced forces and moments on such structures is most important. Following a thorough literature review, the authors proceeded with an experimental study in order to investigate the forces exerted by random waves and a superimposed current on an array of three vertical cylinders as a function of the inter-cylinder gap and the angle of wave incidence over a wide range of wave and current conditions in shallow water.

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Faltinsen, O. M., J. N. Newman, and T. Vinje. "Nonlinear wave loads on a slender vertical cylinder." Journal of Fluid Mechanics 289 (April 25, 1995): 179–98. http://dx.doi.org/10.1017/s0022112095001297.

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The diffraction of water waves by a vertical circular cylinder is considered in the regime where the wave amplitude A and cylinder radius a are of the same order, and both are small compared to the wavelength. The wave slope is small, and a conventional linear analysis applies in the outer domain far from the cylinder. Significant nonlinear effects exist in the complementary inner domain close to the cylinder, associated with the free-surface boundary condition. Using inner coordinates scaled with respect to a, it is shown that the leading-order nonlinear contribution to the velocity potential includes terms proportional to both A2a and A3. The wave load which acts on the cylinder near the free surface includes second- and third-harmonic components which are proportional respectively to A2a2 and A3a. In a conventional perturbation analysis, where A [Lt ] a, these components would be ordered in magnitude corresponding to the different powers of A, but here they are of the same order. The second- and third-order components of the total force are of comparable magnitude for practical values of the wave slope.

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Ageorges, Valentin, Jorge Peixinho, Gaële Perret, Ghislain Lartigue, and Vincent Moureau. "Experiments and Simulations of Free-Surface Flow behind a Finite Height Rigid Vertical Cylinder." Fluids 6, no. 10 (October 18, 2021): 367. http://dx.doi.org/10.3390/fluids6100367.

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We present the results of a combined experimental and numerical study of the free-surface flow behind a finite height rigid vertical cylinder. The experiments measure the drag and the wake angle on cylinders of different diameters for a range of velocities corresponding to 30,000 <Re< 200,000 and 0.2<Fr<2 where the Reynolds and Froude numbers are based on the diameter. The three-dimensional large eddy simulations use a conservative level-set method for the air-water interface, thus predicting the pressure, the vorticity, the free-surface elevation and the onset of air entrainment. The deep flow looks like single phase turbulent flow past a cylinder, but close to the free-surface, the interaction between the wall, the free-surface and the flow is taking place, leading to a reduced cylinder drag and the appearance of V-shaped surface wave patterns. For large velocities, vortex shedding is suppressed in a layer region behind the cylinder below the free surface. The wave patterns mostly follow the capillary-gravity theory, which predicts the crest lines cusps. Interestingly, it also indicates the regions of strong elevation fluctuations and the location of air entrainment observed in the experiments. Overall, these new simulation results, drag, wake angle and onset of air entrainment, compare quantitatively with experiments.

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Tang, Zhong, Haotian Zhang, Yuepeng Zhou, and Yu Li. "Mutual Interference and Coupling Response of Multicylinder Vibration among Combine Harvester Co-Frame." Shock and Vibration 2019 (June 16, 2019): 1–14. http://dx.doi.org/10.1155/2019/1584391.

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Unbalanced vibrations of axial threshing cylinders on a combine harvester were coupled to each other through a frame. The intensified unbalanced vibration will shorten the working life of the axial threshing cylinder. In this paper, the theoretical modes of the axial threshing cylinder were carried out by using finite element analysis software ANSYS. The axis trajectory and speed fluctuation of the axial threshing cylinder under no-load state and threshing state were tested and analyzed. According to the amplitude and axis trajectory of the transmission shaft, as well as the variation law of the axial threshing cylinder speed, the influence of rice straw on the vibration under the threshing state was revealed. The rotation speeds of cylinder I and cylinder III were adjusted, and the amplitude of cylinder II transmission shaft was analyzed when cylinder II was under stable condition. Then the disturbance and coupling relationships among the unbalanced vibration of axial threshing cylinders were compared. Test results showed that the rotational frequency of the axial threshing cylinder was not in its resonance interval at rated speed. When the axial threshing cylinder was threshing, the horizontal amplitude increased by 0.366 mm. The vertical amplitude increased by 0.697 mm. The speed decreased from 763 rpm to about 750 rpm. The rotational frequency of the axial threshing cylinder would not cause the resonance. With the feeding of rice, the amplitude of the axial threshing cylinder increased slightly and the operating speed was lower than the rated speed. The unbalanced vibration of the axial threshing cylinder transmitted along the frame and coupled with each other, causing the vibration of the axial threshing cylinder to be intensified.

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41

Thiagarajan, K. P., and A. W. Troesch. "Hydrodynamic Heave Damping Estimation and Scaling for Tension Leg Platforms." Journal of Offshore Mechanics and Arctic Engineering 116, no. 2 (May 1, 1994): 70–76. http://dx.doi.org/10.1115/1.2920135.

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Resonant heave excitation of tension leg platform (TLP) tendons is typically of high frequency and small amplitude. The response of the tendons to this excitation is non-negligible due to a very small drag coefficient of the structure in this mode of oscillation. Small values of the drag force complicate experimental estimation in a laboratory due to the dominating inertial force. Model tests conducted at the University of Michigan investigating the damping experienced by a cylinder of 0.457 m (1.5 ft) diameter and 1.219 m (4.0 ft) draft are described here. The cylinder is vertical and surface-piercing, and oscillates parallel to its axis. The amplitude of the forcing is varied to give a Keulegan-Carpenter (KC) number range of 0.1–1.0. The frequency parameter β is 89236, corresponding to an oscillation frequency of 0.41 Hz. From these experiments, a definite nonlinear trend is observed between the drag force and velocity conflicting with some of the results reported by Huse (1990) and Chakrabarti and Hanna (1991). The heave damping coefficients of individual structural components of a TLP follow different scaling laws. Rules are presented for scaling friction and form drag components from model to full scale. Results from experiments are used to obtain a scaling law for vertical columns of a TLP. Previously published results are used for horizontal pontoons. An example TLP calculation shows that the heave damping ratio of horizontal cylinders is approximately 0.049–0.078 percent, depending upon cylinder shape, and that for vertical cylinders is in the range 0.025–0.171 percent, depending upon KC.

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42

Henry, D., and B. Roux. "Soret separation in a quasi-vertical cylinder." Journal of Fluid Mechanics 195, no. -1 (October 1988): 175. http://dx.doi.org/10.1017/s002211208800237x.

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43

Demirbilek, Zeki, and Jonathan D. Gaston. "Nonlinear wave loads on a vertical cylinder." Ocean Engineering 12, no. 5 (January 1985): 375–85. http://dx.doi.org/10.1016/0029-8018(85)90001-0.

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44

Mahmood, T., and J. H. Merkin. "Mixed convection on a vertical circular cylinder." ZAMP Zeitschrift f�r angewandte Mathematik und Physik 39, no. 2 (March 1988): 186–203. http://dx.doi.org/10.1007/bf00945765.

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45

Wang, C. Y. "Natural convection on a vertical stretching cylinder." Communications in Nonlinear Science and Numerical Simulation 17, no. 3 (March 2012): 1098–103. http://dx.doi.org/10.1016/j.cnsns.2011.07.033.

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46

Ghalayini, S. A., and A. N. Williams. "Nonlinear wave forces on vertical cylinder arrays." Journal of Fluids and Structures 5, no. 1 (January 1991): 1–32. http://dx.doi.org/10.1016/0889-9746(91)80009-3.

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47

Deng, Yanfei, Jianmin Yang, Wenhua Zhao, Xin Li, and Longfei Xiao. "Freak wave forces on a vertical cylinder." Coastal Engineering 114 (August 2016): 9–18. http://dx.doi.org/10.1016/j.coastaleng.2016.03.007.

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KAGEMOTO, H., M. MURAI, M. SAITO, B. MOLIN, and š. MALENICA. "Experimental and theoretical analysis of the wave decay along a long array of vertical cylinders." Journal of Fluid Mechanics 456 (April 10, 2002): 113–35. http://dx.doi.org/10.1017/s0022112001007480.

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A row of fifty identical, truncated vertical cylinders is submitted to regular head waves, with wave periods in a narrow range around the period of the so-called Neumann trapped mode. The free-surface elevation is measured at 14 locations along the array. Response amplitude operators of the free-surface motion are compared with numerical predictions from a potential flow model. Resonance effects, at wave periods equal to or larger than the critical one, are found to be much less than given by the numerical model. It is advocated that these discrepancies are due to dissipative effects taking place in the boundary layers at the cylinder walls. An artificial means is devised to incorporate dissipation in the potential flow model, whereby the cylinder walls are made slightly porous; the inward normal velocity of the flow is related to the dynamic pressure. The coefficient of proportionality is based on existing knowledge for circular cylinders in oscillatory flows. With this modification in the numerical code, excellent agreement is obtained with the experiments. The numerical model is further used for the case of a very long array composed of 1000 cylinders; it is found that with dissipation at the cylinder walls, the wave action steadily decreases along the array, even for wave periods substantially larger than the critical one. On the other hand, at wave periods less than the critical one, dissipation plays a negligible role; the observed decay is solely due to diffraction effects. Implications of these results for very large structures such as column-supported floating airports are discussed. In particular, it is concluded that scale effects may be an important issue in the experimental analysis of such multi-column structures.

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Bennetts, Luke G., Malte A. Peter, and Fabien Montiel. "Localisation of Rayleigh–Bloch waves and damping of resonant loads on arrays of vertical cylinders." Journal of Fluid Mechanics 813 (January 20, 2017): 508–27. http://dx.doi.org/10.1017/jfm.2016.855.

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Linear potential-flow theory is used to study loads imposed on finite line arrays of rigid, bottom-mounted, surface-piercing, vertical cylinders by surface water waves. Perturbations in the cylinder locations are shown to damp the resonant loads experienced by the unperturbed array. A relationship is established between the damping and the phenomenon of Anderson localisation. Specifically, the Rayleigh–Bloch waves responsible for the resonant loads are shown to attenuate along the array when perturbations are introduced, resulting in localisation when the attenuation rate is sufficiently large with respect to the array length. Further, an efficient solution method for line arrays is introduced that captures the Rayleigh–Bloch wave modes supported by unperturbed arrays from the scattering characteristics of an individual cylinder.

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Chen, Yang, and Wu. "Evolution of Turbulent Horseshoe Vortex System in Front of a Vertical Circular Cylinder in Open Channel." Water 11, no. 10 (October 5, 2019): 2079. http://dx.doi.org/10.3390/w11102079.

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A turbulent horseshoe vortex (HV) system around a wall-mounted cylinder in open channel is characterized by random variations in vortex features and an abundance of vortex interactions. The turbulent HV system is responsible for initiating the local scour process in front of the cylinder. The evolution of the turbulent HV system is investigated statistically and quantitatively with time-resolved particle image velocimetry. The cylinder Reynolds numbers of the flow are 8600, 10,200, and 13,600, respectively. A novel vortex tracking method was proposed to obtain the variations in position, size, and strength of the primary HV (PHV) which dominates the system most of the time. Relationships between the various features of the PHV during its evolutionary process were obtained through correlation analyses. Results show that the dimensionless mean lifespan of the PHV is about 5.0. Statistically, the downstream movement of the PHV toward the cylinder is accompanied with its bed-approaching movement and decreasing in size, and the opposite is true. The circulation strength of the PHV decreases and increases dramatically in the region downstream of its time-averaged position when the PHV approaches and departs from the cylinder, respectively. Meanwhile, mechanisms responsible for the generation, movement, variation, and disappearance of the PHV are re-investigated and enriched based on its interactions with vortices in the separation region and structures in the incoming flow. The obtained change trends of the features of the PHV and the underlying mechanisms for its evolution are valuable for predicting and controlling the initial stage of the local scour in front of cylinders.

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Journal articles on the topic 'Vertical cylinder'

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