Journal articles: 'Film flow analysis'

1

Peng, X. F., and G. P. Peterson. "Analysis of Rewetting for Surface Tension Induced Flow." Journal of Heat Transfer 114, no. 3 (1992): 703–7. http://dx.doi.org/10.1115/1.2911337.

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An analytical investigation was conducted to determine the rewetting characteristics of thin, surface tension driven liquid films over heated plates as a function of the fluid properties, the film thickness, and the applied heat flux. Analytical expressions for the maximum sustainable heat flux and the rewetting velocity were developed for both flat and grooved plates and were compared with data from previous investigations. The results indicated good agreement for low film velocities; however, at high velocities the experimental data deviated significantly from the theoretical predictions. It was hypothesized that this deviation was due to the presence of liquid sputtering near the liquid front. To compensate for this liquid sputtering, the expressions for maximum sustainable heat flux and rewetting velocity were modified using an empirical correction factor developed from the data of previous thin film thickness investigations. The resulting modified expressions were found to compare very favorably with available experimental data over a large range of flow conditions and velocities.

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2

Hagen, Thomas. "Advances in fiber and film flow." Nonlinear Analysis: Theory, Methods & Applications 63, no. 5-7 (2005): e1119-e1130. http://dx.doi.org/10.1016/j.na.2004.12.011.

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Kim, Joon Hyun, and Joo-Hyun Kim. "Thermohydrodynamic Analysis of Surface Roughness in the Flow Field." Journal of Tribology 127, no. 2 (2005): 293–301. http://dx.doi.org/10.1115/1.1828072.

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The study deals with the development of a thermohydrodynamic (THD) computational procedure for evaluating the pressure, temperature, and velocity distributions in fluid films with a very rough geometry. A parametric investigation is performed to predict the bearing behaviors in the lubricating film with the absorbed layers and their interfaces as determined by rough surfaces with Gaussian distribution. The layers are expressed as functions of the standard deviations of each surface to characterize flow patterns between both rough surfaces. Velocity variations and heat generation are assumed to occur in the central (shear) zone with the same bearing length and width. The coupled effect of the surface roughness and shear zone dependency on the hydrodynamic pressure and temperature has been found in the noncontact mode. The procedure confirms the numerically determined relationship between the pressure and film gap, provided that its roughness magnitude is smaller than the fluid film thickness.

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4

Ito, Hisahiro, Masao Doi, Takeharu Isaki, Masaaki Takeo, and Kazuo Yagi. "2D Flow Analysis of Film Casting Process." Nihon Reoroji Gakkaishi 31, no. 3 (2003): 149–55. http://dx.doi.org/10.1678/rheology.31.149.

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Wang, Yingjia, Minshan Liu, Dongchen Qin, and Zhenwei Yan. "Performance of high-speed hydrodynamic sliding bearings with lubricating oils combining laminar and turbulent flows." Advances in Mechanical Engineering 12, no. 6 (2020): 168781402093338. http://dx.doi.org/10.1177/1687814020933389.

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High-speed hydrodynamic sliding bearings use lubricating oil that can have laminar and turbulent flow states, yet turbulent states remain relatively unstudied. This study combines theoretical analysis, numerical modeling, and experiments to analyze lubrication fluids in such bearings. It considers Reynolds equations, energy equations, and temperature-viscosity relationships under laminar and turbulent flows. The governing equations are solved by the finite difference method. Two-dimensional distributions of Reynolds number, pressure, and temperature in the bearing film, as well as the lubrication characteristics like bearing capacity and frictional force under working conditions, are analyzed. Single and mixed flow states are compared, which demonstrates the coexistence states of laminar and turbulent flows in an oil film under specific working conditions. Oil film flow distributions differ significantly according to rotational speed and eccentric conditions. Flow changes under high eccentricity are complex. The characteristics of oil films in a single flow state deviate significantly from those in mixed flow. Changes in flow state and heat should not be ignored during analysis of the lubrication performance of high-speed bearings.

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Usha, R., and B. Uma. "Weakly Nonlinear Stability Analysis of Condensate/Evaporating Power-Law Liquid Film Down an Inclined Plane." Journal of Applied Mechanics 70, no. 6 (2003): 915–23. http://dx.doi.org/10.1115/1.1631592.

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Weakly nonlinear stability analysis of thin power-law liquid film flowing down an inclined plane including the phase change effects at the interface has been investigated. A normal mode approach and the method of multiple scales are employed to carry out the linear stability solution and the nonlinear stability solution for the film flow system. The results show that both the supercritical stability and subcritical instability are possible for condensate, evaporating and isothermal power-law liquid film down an inclined plane. The stability characteristics of the power-law liquid film show that isothermal and evaporating films are unstable for any value of power-law index ‘n’ while there exists a critical value of power-law index ‘n’ for the case of condensate film above which condensate film flow system is always stable. Thus, the results of the present analysis show that the mass transfer effects play a significant role in modifying the stability characteristics of the non-Newtonian power-law fluid flow system. The condensate (evaporating) power-law fluid film is more stable (unstable) than the isothermal power-law fluid film flowing down an inclined plane.

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7

Cheng, P. J., K. C. Liu, and D. T. W. Lin. "Hydromagnetic Stability Analysis of a Film Coating Flow Down a Rotating Vertical Cylinder." Journal of Mechanics 27, no. 1 (2011): 27–36. http://dx.doi.org/10.1017/jmech.2011.4.

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ABSTRACTThe influence of both the Rossby number and the Hartmann number on the hydromagnetic stability of a thin liquid film flowing down along the surface of a vertical cylinder is investigated. The long-wave perturbation method is employed to solve for generalized nonlinear kinematic equations with a free film interface. The normal mode approach is used to compute the stability solution for the film flow. The modeling results indicate that the stability of the liquid film is enhanced by increasing the strength of the magnetic field or reducing the speed at which the cylinder rotates. By contrast, the flow becomes relatively more unstable as the cylinder radius is increased at larger values of the Rossby number. Notably, this finding is the opposite of that observed for film flows along a stationary vertical cylinder.

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Pacheco, J. Rafael, and Arturo Pacheco-Vega. "Analysis of Thin Film Flows Using a Flux Vector Splitting1." Journal of Fluids Engineering 125, no. 2 (2003): 365–74. http://dx.doi.org/10.1115/1.1538626.

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We propose a flux vector splitting (FVS) for the solution of film flows radially spreading on a flat surface created by an impinging jet using the shallow-water approximation. The governing equations along with the boundary conditions are transformed from the physical to the computational domain and solved in a rectangular grid. A first-order upwind finite difference scheme is used at the point of the shock while a second-order upwind differentiation is applied elsewhere. Higher-order spatial accuracy is achieved by introducing a MUSCL approach. Three thin film flow problems (1) one-dimensional dam break problem, (2) radial flow without jump, and (3) radial flow with jump, are investigated with emphasis in the prediction of hydraulic jumps. Results demonstrate that the method is useful and accurate in solving the shallow water equations for several flow conditions.

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9

Akhtaruzzaman, Md, Md Shahiduzzaman, Nowshad Amin, et al. "Impact of Ar Flow Rates on Micro-Structural Properties of WS2 Thin Film by RF Magnetron Sputtering." Nanomaterials 11, no. 7 (2021): 1635. http://dx.doi.org/10.3390/nano11071635.

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Tungsten disulfide (WS2) thin films were deposited on soda-lime glass (SLG) substrates using radio frequency (RF) magnetron sputtering at different Ar flow rates (3 to 7 sccm). The effect of Ar flow rates on the structural, morphology, and electrical properties of the WS2 thin films was investigated thoroughly. Structural analysis exhibited that all the as-grown films showed the highest peak at (101) plane corresponds to rhombohedral phase. The crystalline size of the film ranged from 11.2 to 35.6 nm, while dislocation density ranged from 7.8 × 1014 to 26.29 × 1015 lines/m2. All these findings indicate that as-grown WS2 films are induced with various degrees of defects, which were visible in the FESEM images. FESEM images also identified the distorted crystallographic structure for all the films except the film deposited at 5 sccm of Ar gas flow rate. EDX analysis found that all the films were having a sulfur deficit and suggested that WS2 thin film bears edge defects in its structure. Further, electrical analysis confirms that tailoring of structural defects in WS2 thin film can be possible by the varying Ar gas flow rates. All these findings articulate that Ar gas flow rate is one of the important process parameters in RF magnetron sputtering that could affect the morphology, electrical properties, and structural properties of WS2 thin film. Finally, the simulation study validates the experimental results and encourages the use of WS2 as a buffer layer of CdTe-based solar cells.

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10

Henrichsen, L. K., and A. J. McHugh. "Analysis of Film Blowing with Flow-enhanced Crystallization." International Polymer Processing 22, no. 2 (2007): 179–89. http://dx.doi.org/10.3139/217.1003.

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Henrichsen, L. K., and A. J. McHugh. "Analysis of Film Blowing with Flow-enhanced Crystallization." International Polymer Processing 22, no. 2 (2007): 190–97. http://dx.doi.org/10.3139/217.1004.

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12

Jolley, Sharlene, Miles Koppang, Tom Jackson, and Greg M. Swain. "Flow Injection Analysis with Diamond Thin-Film Detectors." Analytical Chemistry 69, no. 20 (1997): 4099–107. http://dx.doi.org/10.1021/ac961269x.

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13

Abu-Abdou, Khalil M. K. "Analysis of continuous-flow thin-film solar stills." Renewable Energy 4, no. 7 (1994): 839–45. http://dx.doi.org/10.1016/0960-1481(94)90236-4.

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14

Wen, Hung Jiun, Fuh Liang Wen, Kuo Hwa Chang, C. H. Wen, and Yu Lin Lo. "Effect Analysis of Ar-N₂ Flow Rates on ZrN_X Film by Pulsed Magnetron Sputtering Using Design of Experimental Method." Advanced Materials Research 194-196 (February 2011): 2491–98. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.2491.

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The various nitrogen gas (N2) flows for depositing zirconium-nitride (ZrN) films on the substrate of a p-type (100) silicon wafer are investigated through reactive magnetron sputtering by a pulsed-DC power. The results, based on the design of experimental (DOE) method, indicate that the deposition effect of the ZrNx film is obviously affected by various flow rates of nitrogen gas at the specific pulsing duty cycles. The crystal orientation of the zirconium-nitride film has a less order microstructure which is similar to an amorphous microstructure. Although the composition ratio of chemical elements is not identical in Zr and N, the surface roughness, grain size, and resistivity are the better feature. The deposition rate is inversely proportional to the nitrogen flow rate and the chamber pressure is also an important factor. The basic effect of N2 flow rate on the surface roughness is rougher when more nitrogen gas is supplied. The resistivity of ZrNx thin film has a positive relationship to N2 flow rates at the reactive vacuum chamber.

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15

Camassa, Roberto, H. Reed Ogrosky, and Jeffrey Olander. "Viscous film flow coating the interior of a vertical tube. Part 1. Gravity-driven flow." Journal of Fluid Mechanics 745 (March 25, 2014): 682–715. http://dx.doi.org/10.1017/jfm.2014.90.

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AbstractThe gravity-driven flow of a viscous liquid film coating the inside of a tube is studied both theoretically and experimentally. As the film moves downward, small perturbations to the free surface grow due to surface tension effects and can form liquid plugs. A first-principles strongly nonlinear model based on long-wave asymptotics is developed to provide simplified governing equations for the motion of the film flow. Linear stability analysis on the basic solution of the model predicts the speed and wavelength of the most unstable mode, and whether the film is convectively or absolutely unstable. These results are found to be in remarkable agreement with the experiments. The model is also solved numerically to follow the time evolution of instabilities. For relatively thin films, these instabilities saturate as a series of small-amplitude travelling waves, while thicker films lead to solutions whose amplitude becomes large enough for the liquid surface to approach the centre of the tube in finite time, suggesting liquid plug formation. Next, the model’s periodic travelling wave solutions are determined by a continuation algorithm using the results from the time evolution code as initial seed. It is found that bifurcation branches for these solutions exist, and the critical turning points where branches merge determine film mean thicknesses beyond which no travelling wave solutions exist. These critical thickness values are in good agreement with those for liquid plug formations determined experimentally and numerically by the time-evolution code.

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16

Venerus, David C. "Squeeze flows in liquid films bound by porous disks." Journal of Fluid Mechanics 855 (September 21, 2018): 860–81. http://dx.doi.org/10.1017/jfm.2018.635.

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Squeeze flows in liquid films between a porous disk and an impermeable disk generated by the relative motion of the disks are analysed. Two configurations that differ by the arrangement of (im)permeable external surfaces that bound the porous disk (i.e. not in contact with the liquid film) are considered. Such configurations allow for bearings with tuneable load-bearing characteristics and are also encountered in joint lubrication, adhesion, printing and composite manufacturing. In the present study, flow in the porous disk is governed by Darcy’s law and flow in the liquid film is described using lubrication theory. The present analysis also allows for slip between the liquid film and porous disk. Analytical solutions of the coupled system of equations governing flow in the liquid film and the porous disk are found. Under certain conditions, somewhat unexpected flow patterns are observed in the porous disk. The load-bearing capacity for both configurations is also examined as a function of the permeability and geometry of the permeable disk.

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17

WILSON, M. C. T., P. H. GASKELL, and M. D. SAVAGE. "Flow in a double-film-fed fluid bead between contra-rotating rolls Part 1: equilibrium flow structure." European Journal of Applied Mathematics 12, no. 3 (2001): 395–411. http://dx.doi.org/10.1017/s0956792501004399.

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In multiple-roll coaters thin liquid films are transferred from roll to roll by means of liquid ‘beads’ which occupy the small gaps between adjacent rolls. Double-Film-Fed (DFF) beads are those which feature two ingoing films instead of the usual one, and arise in the intermediate stages of certain types of roll coater. One of the ingoing films, h1, is supplied from the previous inter-roll gap while the other, h2, ‘returns’ from the subsequent gap. Such a flow is investigated here under the conditions of low flow rate, small capillary number and negligible gravity and inertia, using lubrication theory and finite element analysis. The thickness of film h1 is fixed independently, while that of h2 is specified as a fraction, ζ, of the film output on the same roll. This simple approach allows a degree of feedback between the output and input of the bead, and enables one to simulate different conditions in the subsequent gap. Predictions of outgoing film thicknesses made using the two models agree extremely well and show that, for each value of ζ < 1, one outgoing film thickness decreases monotonically with speed ratio, S, while the other features a maximum. Good agreement is also seen in the pressure profiles, which are entirely sub-ambient in keeping with the small capillary number conditions. The finite element solutions reveal that in the ‘zero-flux’ case (when ζ = 1) the flow structures are very similar to those seen in an idealized cavity problem. In the more general (ζ < 1) situation, as in single-film-fed meniscus roll coating, several liquid transfer-jets occur by which liquid is conveyed through the bead from one roll to the other. The lubrication model is used to calculate several critical flow rates at which the flow is transformed, and it is shown that when the total dimensionless flow rate through the bead exceeds 1/3, the downstream flow structure is independent of the relative sizes of the ingoing films.

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Shu, Wei Chu, Tsai Fang Wu, Ren Haw Chen, Kuei Yuan Cheng, and Chih Wei Hsieh. "Flow and Film-Forming Characteristics Analysis of Non-Newtonian Fluid Slot Coating." Advanced Materials Research 939 (May 2014): 539–46. http://dx.doi.org/10.4028/www.scientific.net/amr.939.539.

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The slot coating process in the production of polymer films has a wide range of applications. However, the process cannot be systemized. This study used the computational fluid dynamics software Polyflow to analyze the slot coating process and investigate the influence that the process parameters have on the characteristics of thin-film coating to reduce the time and cost consumed in the experimental methods. The rheological characteristics of the non-Newtonian fluid used in this study were first identified by conducting experiments, and then configured in the simulation software for fitting with mathematical models. In addition, the models of the slot coating process were constructed, and the Arbitrary Lagrangian-Eulerian (ALE) calculation methods were then used in the Polyflow software. The simulation results were then compared to the experimental results and the findings reported in relevant literature, to determine the influence that the process parameters have on the characteristics of thin-film coating. The simulation results were represented graphically in a coating window plot. The comparison results indicate that the viscosity-shear rate characteristic of the material in the shear rate range of optical film coating is an excellent fit for the Cross Law. When the coating speed is too high or the amount of fluid supply is insufficient, phenomena such as break lines, uneven thickness, and air entrainment can occur.

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Luo, Yuxi, Fengbo Wen, Rui Hou, Shuai Wang, Songtao Wang, and Zhongqi Wang. "Modal analysis of trailing edge cutback film cooling." International Journal of Numerical Methods for Heat & Fluid Flow 30, no. 8 (2019): 3957–83. http://dx.doi.org/10.1108/hff-09-2019-0673.

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Purpose The purpose of this paper devoted to the application of modal analysis to analyze the flow structure of trailing edge cutback film cooling and the effects of vortex structure on the film cooling effectiveness of the cutback surface. Design/methodology/approach Large eddy simulation (LES) is used to simulate the trailing edge cutback film cooling. The results of LES are analyzed by proper orthogonal decomposition (POD) method and dynamic mode decomposition (DMD) method. The POD method is used to determine the dominated vortex structure and the energy level of these structures. The DMD method is used to analyze the relationship between vortex structures and wall temperature. Findings The POD method shows that the flow field consists of three main vortices – streamwise vortex, lip vortex and coolant vortex. The DMD results show that the lip vortex mainly acts on the middle section of the cutback surface, while the streamwise vortex mainly acts on the back section of the cutback surface. Research limitations/implications The modal analysis is only based on numerical simulation but the modal analysis of experimental results will be further studied in the future. Practical implications This paper presents the powerful ability of the modal analysis method to study complex flows in trailing edge cutback film cooling. Establishing the relationship between vortex and wall temperature by modal analysis method can provide a new idea for studying convective heat transfer problems. Originality/value The role of streamwise vortex in the flow of the trailing edge cutback cooling and its effect on the cooling effectiveness of the cutback surface is found.

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20

Ott, H. H., and G. Paradissiadis. "Thermohydrodynamic Analysis of Journal Bearings Considering Cavitation and Reverse Flow." Journal of Tribology 110, no. 3 (1988): 439–47. http://dx.doi.org/10.1115/1.3261648.

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The flow field of a hydrodynamic journal bearing is calculated by the iterative solution of the system of Reynolds and energy equations. In the case of reverse flow at the film inlet, the temperature profile there can not be prescribed as a boundary condition but has to be determined from the flow in the film. This is achieved by a separate integration of the energy equation in the reverse flow area. The flow in the cavitation regions is approximated by a theoretical model leading to a form of the energy equation similar to that for pressure regions, thus enabling the integration of the energy equation over the whole film.

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21

Salant, Richard F., and Ann H. Rocke. "Hydrodynamic Analysis of the Flow in a Rotary Lip Seal Using Flow Factors." Journal of Tribology 126, no. 1 (2004): 156–61. http://dx.doi.org/10.1115/1.1609486.

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The flow field in the lubricating film of a rotary lip seal is analyzed numerically by solving the Reynolds equation with flow factors. The behavior of such a flow field is dominated by the asperities on the lip surface. Since previous analyses treated those asperities deterministically, they required very large computation times. The present approach is much less computationally intensive because the asperities are treated statistically. Since cavitation and asperity orientation play important roles, these are taken into account in the computation of the flow factors. Results of the analysis show how the operating parameters of the seal and the characteristics of the asperities affect such seal characteristics as the pressure distribution in the film, the pumping rate and the load support.

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Subramani, Shanmugan, and Mutharasu Devarajan. "Structural and surface analysis of chemical vapor deposited boron doped aluminum nitride thin film on aluminum substrates." Materials Science-Poland 37, no. 3 (2019): 395–403. http://dx.doi.org/10.2478/msp-2019-0056.

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AbstractChemical vapor deposition (CVD) process was conducted for synthesis of boron (B) doped aluminum nitride (B-AlN) thin films on aluminum (Al) substrates. To prevent melting of the Al substrates, film deposition was carried out at 500 °C using tert-buthylamine (tBuNH2) solution delivered through a bubbler as a nitrogen source instead of ammonia gas (NH3). B-AlN thin films were prepared from three precursors at changing process parameters (gas mixture ratio). X-ray diffraction (XRD) technique and atomic force microscope (AFM) were used to investigate the structural and surface properties of B-AlN thin films on Al substrates. The prepared thin films were polycrystalline and composed of mixed phases {cubic (1 1 1) and hexagonal (1 0 0)} of AlN and BN with different orientations. Intensive AlN peak of high intensity was observed for the film deposited at a flow rate of the total gas mixture of 25 sccm. As the total gas mixture flow decreased from 60 sccm to 25 sccm, the crystallite size of AlN phase increased and the dislocation density decreased. Reduced surface roughness (10.4 nm) was detected by AFM for B-AlN thin film deposited on Al substrate using the lowest flow rate (25 sccm) of the total gas mixture.

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23

Elangovan, T., D. Mangalaraj, K. Prabakar, P. Kuppusami, Shabana Khan, and E. Mohandas. "Microstructure Analysis of TaN/Cu Nanocomposite Coatings Deposited by Pulsed DC Magnetron Sputtering." Advanced Materials Research 123-125 (August 2010): 427–30. http://dx.doi.org/10.4028/www.scientific.net/amr.123-125.427.

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TaN-Cu nanocomposite thin films used as materials for thin-film resistors (TFR) were prepared by magnetron pulsed dc reactive sputtering. Structural and morphological properties of films deposited on (100) Si as a function of nitrogen flow rate and substrate temperature is investigated. With the introduction of N2 gas flow indicated with different phases of nanocrystalline h-Ta, Ta2N, TaN, Ta4N5 and Cu. XRD analysis of the films deposited with increasing substrate temperature at constant flow rate of nitrogen 10 sccm indicated that the nanocrystalline with bi-phasic (fcc-TaN and fcc-Cu). The microstructure of the films was investigated by scanning electron microscopy and high-resolution transmission electron microscopy.

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Cheng, Po-Jen, Cha’o-Kuang Chen, and Hsin-Yi Lai. "Nonlinear Stability Analysis of the Thin Micropolar Liquid Film Flowing Down on a Vertical Cylinder." Journal of Fluids Engineering 123, no. 2 (2000): 411–21. http://dx.doi.org/10.1115/1.1359524.

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This paper investigates the weakly nonlinear stability theory of a thin micropolar liquid film flowing down along the outside surface of a vertical cylinder. The long-wave perturbation method is employed to solve for generalized nonlinear kinematic equations with free film interface. The normal mode approach is first used to compute the linear stability solution for the film flow. The method of multiple scales is then used to obtain the weak nonlinear dynamics of the film flow for stability analysis. The modeling results indicate that both subcritical instability and supercritical stability conditions are possible to occur in a micropolar film flow system. The degree of instability in the film flow is further intensified by the lateral curvature of cylinder. This is somewhat different from that of the planar flow. The modeling results also indicate that by increasing the micropolar parameter K=κ/μ and increasing the radius of the cylinder the film flow can become relatively more stable traveling down along the vertical cylinder.

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Cheng, Po-Jen, and Kuo-Chi Liu. "STABILITY ANALYSIS OF THE THIN POWER LAW LIQUID FILM FLOWING DOWN ON A VERTICAL CYLINDER." Transactions of the Canadian Society for Mechanical Engineering 30, no. 1 (2006): 81–96. http://dx.doi.org/10.1139/tcsme-2006-0006.

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The paper investigates the stability theory of a thin power law liquid film flowing down along the outside surface of a vertical cylinder. The long-wave perturbation method is employed to solve for generalized linear kinematic equations with free film interface. The normal mode approach is used to compute the stability solution for the film flow. The degree of instability in the film flow is further intensified by the lateral curvature of cylinder. This is somewhat different from that of the planar flow. The analysis results also indicate that by increasing the flow index and increasing the radius of the cylinder the film flow can become relatively more stable as traveling down along the vertical cylinder.

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Miró, Manuel, Andreu Cladera, José Manuel Estela, and Vı́ctor Cerdà. "Dual wetting-film multi-syringe flow injection analysis extraction." Analytica Chimica Acta 438, no. 1-2 (2001): 103–16. http://dx.doi.org/10.1016/s0003-2670(00)01356-8.

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Chun-Sik Park. "The analysis of the flow of main-melody film." Journal of Chinese Language and Literature ll, no. 53 (2009): 241–61. http://dx.doi.org/10.15792/clsyn..53.200906.241.

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Emhofer, J., B. Beladi, P. Dudzinski, T. Fleckl, and H. C. Kuhlmann. "Analysis of a cross-flow liquid-desiccant falling-film." Applied Thermal Engineering 124 (September 2017): 91–102. http://dx.doi.org/10.1016/j.applthermaleng.2017.05.130.

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Gräf, Lars, and Leonhard Kleiser. "Flow-field analysis of anti-kidney vortex film cooling." Journal of Thermal Science 21, no. 1 (2012): 66–76. http://dx.doi.org/10.1007/s11630-012-0520-y.

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Cheng, Po-Jen, and I.-Peng Chu. "Nonlinear hydromagnetic stability analysis of a pseudoplastic film flow." Aerospace Science and Technology 13, no. 4-5 (2009): 247–55. http://dx.doi.org/10.1016/j.ast.2009.04.003.

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Cheng, P. J., and K. C. Liu. "Stability Analysis on Viscous Magnetic Fluid Film Flowing Down Along a Vertical Cylinder." Journal of Mechanics 23, no. 2 (2007): 127–34. http://dx.doi.org/10.1017/s1727719100001155.

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AbstractThe paper investigates the hydromagnetic stability theory of a thin electrically conductive fluid film flowing down along the outside surface of a vertical cylinder. The long-wave perturbation method is employed to solve for generalized kinematic equations with free film interface. The normal mode approach is used to compute the stability solution for the film flow. The modeling results display that the degree of instability in the film flow is further intensified by the lateral curvature of cylinder. This is somewhat different from that of the planar flow. It is also observed that by increasing the effect of the magnetic field and increasing the radius of the cylinder the film flow can become relatively more stable as traveling down along the vertical cylinder.

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Socolowsky, Jürgen. "ON A TWO-FLUID INCLINED FILM FLOW WITH EVAPORATION." Mathematical Modelling and Analysis 18, no. 1 (2013): 22–31. http://dx.doi.org/10.3846/13926292.2013.756434.

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This paper is concerned with a plane steady-state inclined film flow including evaporation effects. The motion is governed by a free boundary value problem for a coupled system of Navier–Stokes and Stefan equations. The flow domain is unbounded in two directions and it contains a geometrical perturbation on the inclined bottom. Existence and uniqueness of a suitable solution in weighted Sobolev spaces can be proved for small data (perturbation, inclination of the bottom) characterizing the problem.

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Sun, Pan Pan, Shu Zhong Wang, Yan Hui Li, and Xue Dong Li. "Numerical Analysis on Heat Transfer and Oxidation Characteristics of High-Temperature Steam Pipes in Supercritical Units." Advanced Materials Research 908 (March 2014): 81–84. http://dx.doi.org/10.4028/www.scientific.net/amr.908.81.

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In this paper, for Super304H steel, the growth law of oxide films and the heat transfer characteristics between the pipe and the working fluid were investigated by using numerical software ANSYS, which simulated comprehensively the effects of pipe size, flow rates of steam, flue gas temperature, and steam temperature on the formation and thickness of the oxide film. A bigger pipe wall thickness, a smaller steam flow rate or a higher flue gas temperature will lead the faster growth of the oxide film thickness, the heat flux density through the wall being smaller and the wall temperature being higher. With increases in steam temperature and thickness of the oxide film, the heat flux through the wall decreases with a small amplitude, and the average temperature of tube walls increases slightly.

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Saiki, Hiroyuki, Yasuo Marumo, Li Qun Ruan, and Junpei Kozasa. "Estimation of Contact Interface between Tool and Workpiece in Cold Forming Using FEM Analysis." Materials Science Forum 539-543 (March 2007): 2275–80. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.2275.

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The effect of the flow stress of solid lubricant for cold forging on the tribological conditions was investigated using a rigid-plastic finite element method. The thickness of lubricant film decreases with decreasing flow stress of the solid lubricant and then decreases rapidly. The apparent friction coefficient also decreases with the decrease in the flow stress of the solid lubricant. The thickness of lubricant film tends to decrease with decreasing friction shear factor. When flow stress of solid lubricant is low, the thickness of lubricant film decreases remarkably with increasing tool stroke. We can observe a good correlation between the flow stress of solid lubricant, friction shear factor, minimum film thickness and apparent friction coefficient.

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Jung, C. K., I. S. Bae, Y. H. Song, S. J. Cho, and Jin Hyo Boo. "Characterization of TiOxNy Films Grown by PECVD Method: Structural and Optical Properties." Solid State Phenomena 111 (April 2006): 151–54. http://dx.doi.org/10.4028/www.scientific.net/ssp.111.151.

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Titanium oxynitride (TiOxNy) films were prepared by RF PECVD on Si(100) and glass substrates using nitrogen and argon mixture gas. Titanium iso-propoxide (Ti[OCH(CH3) 2] 4, 97%) was used as precursor with different nitrogen flow rate to control oxygen and nitrogen contents in the films. Changes of chemical states of constituent elements in the deposited films were examined by X-ray photoelectron spectroscopy (XPS) analysis. With increasing nitrogen flow rate the total amount of nitrogen was increased while that of oxygen was decreased. The film growth orientation and N-H peak intensity characteristics were also analyzed by X-ray diffraction (XRD), atomic force microscopy (AFM), and infrared spectroscopy (FT-IR). Through refractive index as well as contact angle analysis, we can suggest that relationship to surface energy and optical property. Moreover, transmission electron microscopy (TEM) was also used to investigate the morphology of TiOxNy thin film and the phase of the TiOxNy thin film different nitrogen flow rate.

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Sinkunas, Stasys, Jonas Gylys, and Algimantas Kiela. "Theoretical and Experimental Analysis of Turbulent Liquid Film Flowing down a Vertical Surface." Applied Mechanics and Materials 15 (August 2009): 3–8. http://dx.doi.org/10.4028/www.scientific.net/amm.15.3.

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The purpose of the present study is to obtain a comprehension for the momentum and heat transfer developments in gravitational liquid film flow. Analytical study of stabilized heat transfer for turbulent film was performed. A calculation method of the local heat transfer coefficient for a turbulent film falling down a vertical convex surface was proposed. The dependence of heat flux variation upon the distance from the wetted surface has been established analytically. Experimental study of velocity profiles for turbulent liquid film flow in the entrance region is performed as well. Analysis of profiles allowed estimating the length of stabilization for turbulent film flow under different initial velocities.

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Liu, Xiao Bo, Jian Run Zhang, Pu Li, and Xin Hua Wang. "Analysis and Calculation of Vacuum Film Deaeration for High Viscosity Liquids." Applied Mechanics and Materials 141 (November 2011): 76–82. http://dx.doi.org/10.4028/www.scientific.net/amm.141.76.

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A theoretical analysis of Vacuum Film Deaeration(VFD) based on the characteristics of fluid film on a rotating cone surface is carried out. The motion equation of bubble is derived to find out its relative slip velocity in the flowing film. And the bubbles removal time from the high viscosity liquid is discussed. The thickness model of liquid film on the rotating surface and the residence time of the film flows over the surface are built in this paper. It is found that the thickness and the velocity of the flowing film on the rotating cone surface are the key parameters for VFD; the time of bubble remove mainly includes the growth time and the rest time; the velocity of bubble is slightly lagging behind the main flow; the low angular velocity has little effect on the film thickness; and the time of VFD for flowing film is less than that of static film.

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Hegarty, Alan F., Stephen B. G. O'Brien, and Stephen Sikwila. "Numerical Solution of a Rimming Flow Problem Using a Moving Mesh Method." Computational Methods in Applied Mathematics 3, no. 3 (2003): 373–86. http://dx.doi.org/10.2478/cmam-2003-0024.

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AbstractWe consider the evolution of a thin film of viscous fluid on the inside surface of a cylinder with the horizontal axis, rotating with a constant angular velocity about this axis. We use a lubrication approximation extended to the first order in the dimensionless film thickness (including the small effects of the variation of the film pressure across its thickness and the surface tension) and numerically we compute the time evolution of the film to a steady state.

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&NA;. "ANTITHROMBOGENIC SECONDARY FLOW ANALYSIS FOR BLOOD PUMPS WITH FLOW VISUALIZATION OIL FILM METHOD." ASAIO Journal 44, no. 2 (1998): 51A. http://dx.doi.org/10.1097/00002480-199803000-00188.

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Yang, Zhou, L. San Andres, and D. W. Childs. "Thermohydrodynamic Analysis of Process-Liquid Hydrostatic Journal Bearings in Turbulent Regime, Part I: The Model and Perturbation Analysis." Journal of Applied Mechanics 62, no. 3 (1995): 674–78. http://dx.doi.org/10.1115/1.2895999.

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A bulk-flow thermohydrodynamic (THD) analysis is developed for prediction of the static and dynamic performance characteristics of turbulent-flow, process-liquid, hydrostatic journal bearings (HJBs). Pointwise evaluation of temperature and hence liquid properties is achieved through the solution of the energy equation in the fluid film with insulated boundaries, and justified for fluid film bearings with external pressurization. Fluid inertia within the film lands and at recess edges is preserved in the analysis. Flow turbulence is accounted through turbulence shear parameters based on friction factors derived from Moody’s formulae. The effects of fluid compressibility and temperature variation in the bearing recesses are included. Numerical solution and results are presented in the second part of this work and compared with some limited experimental data for a liquid hydrogen (LH2) bearing.

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Lee, Chong Mu, Keun Bin Yim, and Choong Mo Kim. "Dependence of Electrical and Optical Properties of the Al Doped ZnO for Transparent Conductors Deposited by rf–Magnetron Sputtering on the O₂/Ar Gas Flow Ratio." Key Engineering Materials 336-338 (April 2007): 564–66. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.564.

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ZnO:Al thin films were deposited on sapphire(001) substrates by RF magnetron sputtering. Effects of the O2/Ar flow ratio in the sputtering process on the crystallinity, surface roughness, carrier concentration, carrier mobility, and optical properties of the films were investigated. AFM analysis results show that the surface roughness is lowest at the O2/Ar flow ratio of 0.5 and tends to increase owing to the increase of the grain size as the O2/Ar flow ratio increases further than 0.5. According to the Hall measurement results the resistivity increases as the O2/Ar flow ratio increases. The transmittance of the film tends to increase as the O2/Ar gas flow ratio increases up to 0.5 but it nearly does not change with continued increases in the O2/Ar flow ratio. Considering the effects of the the O2/Ar flow ratio on the surface roughness, electrical resistivity and transmittance properties of the ZnO:Al film the optimum O2/Ar flow ratio is 0.5 in the RF magnetron sputter deposition of the ZnO:Al film.

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42

San Andre´s, Luis. "Bulk-Flow Analysis of Hybrid Thrust Bearings for Process Fluid Applications." Journal of Tribology 122, no. 1 (1999): 170–80. http://dx.doi.org/10.1115/1.555340.

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Advanced cryogenic fluid turbopumps are very compact, operate at extremely high shaft speeds, and require hybrid (hydrostatic/hydrodynamic) radial and thrust fluid film bearings for accurate rotor positioning. Sound design and reliable operation of fluid film thrust bearings also allows for unshrouded impellers with a significant increase in the turbopump mechanical efficiency. A bulk-flow analysis for prediction of the static load performance and dynamic force coefficients of high speed, angled injection orifice-compensated, hybrid (hydrostatic/hydrodynamic) thrust bearings is presented. The model accounts for the bulk-flow mass, momentum and thermal energy transport, and includes flow turbulence and fluid inertia (advection and centrifugal) effects on the bearing film lands and recesses. The performance of a refrigerant hybrid thrust bearing for an oil-free air conditioning equipment is evaluated at two operating speeds and pressure differentials. The computed results are presented in dimensionless form to evidence consistent trends in the bearing performance characteristics. As the applied axial load increases, the bearing film thickness and flow rate decrease while the recess pressure increases. The axial stiffness coefficient shows a maximum for a certain intermediate load while the damping coefficient steadily increases with load. The computed results show the significance of centrifugal fluid inertia at low recess pressures (i.e. low loads) and high rotational speeds, and which can lead to film starvation at the bearing inner radius and subambient pressures just downstream of the bearing recess edge. [S0742-4787(00)02201-3]

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AFZAL, NAVEED, MUTHARASU DEVARAJAN, and KAMARULAZIZI IBRAHIM. "DEPOSITION AND CHARACTERIZATION OF MAGNETRON CO-SPUTTERED InAlN FILM AT DIFFERENT Ar:N2 GAS FLOW RATIOS." Surface Review and Letters 24, no. 03 (2017): 1750027. http://dx.doi.org/10.1142/s0218625x17500275.

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This work presents the influence of changing Ar:N2 gas ratio on the growth and properties of InAlN films. InAlN films were deposited on [Formula: see text]-type Si(111) substrates by using magnetron co-sputtering method in 6:12, 10:10, 12:8 and 12:6 Ar:N2 mixtures at 300[Formula: see text]C. The surface, structural, electrical and optical properties of the deposited films were evaluated at different Ar:N2 ratios. The grain size and film thickness were increased by increasing the Ar flow with respect to N2. Structural characterization by X-ray diffraction (XRD) revealed an improvement in the crystalline quality of the [Formula: see text]-axis-oriented InAlN film by adjusting the Ar:N2 ratio to 12:8, however no diffraction peak corresponding to InAlN was detected at 6:12 Ar:N2 mixture. The surface roughness of InAlN film exhibited an increasing trend whereas the electrical resistivity of the film was decreased by increasing the Ar:N2 ratio. The bandgap of InAlN film was calculated from the optical reflectance spectra and it was found to change by changing the Ar:N2 gas ratio. The analysis of results from this work shows that the InAlN film with improved physical properties can be obtained through reactive magnetron co-sputtering method by adjusting the Ar:N2mixture to 12:8.

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Ruschak, Kenneth J., and Steven J. Weinstein. "Thin-Film Flow at Moderate Reynolds Number." Journal of Fluids Engineering 122, no. 4 (2000): 774–78. http://dx.doi.org/10.1115/1.1319499.

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Viscous, laminar, gravitationally-driven flow of a thin film over a round-crested weir is analyzed for moderate Reynolds numbers. A previous analysis of this flow utilized a momentum integral approach with a semiparabolic velocity profile to obtain an equation for the film thickness (Ruschak, K. J., and Weinstein, S. J., 1999, “Viscous Thin-Film Flow Over a Round-Crested Weir,” ASME J. Fluids Eng., 121, pp. 673–677). In this work, a viscous boundary layer is introduced in the manner of Haugen (Haugen, R., 1968, “Laminar Flow Around a Vertical Wall,” ASME J. Appl. Mech. 35, pp. 631–633). As in the previous analysis of Ruschak and Weinstein, the approximate equations have a critical point that provides an internal boundary condition for a bounded solution. The complication of a boundary layer is found to have little effect on the thickness profile while introducing a weak singularity at its beginning. The thickness of the boundary layer grows rapidly, and there is little cumulative effect of the increased wall friction. Regardless of whether a boundary layer is incorporated, the approximate free-surface profiles are close to profiles from finite-element solutions of the Navier-Stokes equation. Similar results are obtained for the related problem of developing flow on a vertical wall (Cerro, R. L., and Whitaker, S., 1971, “Entrance Region Flows With a Free Surface: the Falling Liquid Film,” Chem. Eng. Sci., 26, pp. 785–798). Less accurate results are obtained for decelerating flow on a horizontal wall (Watson, E. J., 1964, “The Radial Spread of a Liquid Jet Over a Horizontal Plane,” J. Fluid Mech. 20, pp. 481–499) where the flow is not gravitationally driven. [S0098-2202(00)01904-0]

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Rahman, S. A., M. Z. Othman, and P. W. May. "Raman and Photoluminescence Spectroscopy of Nanocrystalline Diamond Films Grown by Hot Filament CVD." Advanced Materials Research 501 (April 2012): 271–75. http://dx.doi.org/10.4028/www.scientific.net/amr.501.271.

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Nanocrystalline diamond films were grown by hot filament chemical vapour deposition (HFCVD) in a mixture of methane and hydrogen gases. Three straight parallel wires filament configuration were used in the HFCVD system for the deposition of the films studied in this work. The deposition pressure for the growth of diamond films in this hot filament chemical vapour deposition (HFCVD) reactor have been optimized to be at 20 torr with the methane and hydrogen flow-rates fixed at 2 and 200 sccm respectively. The films studied in this work were grown at low deposition pressures of 2 and 5 torr using the same gas flow-rates used for the optimized diamond film growth including an additional film grown at pressure of 5 mbar with the methane flow-rate reduced to 1 sccm. The morphology showed the formation of closed packed diamond grains for the film grown at 5 torr with methane and hydrogen flow-rates fixed at 2 and 200 sccm. Decrease in pressure and methane flow-rate produced significant changes to the morphology of the diamond grains formed. X-ray diffraction showed that diamond phase phases were dominant in the films deposited at higher pressure. Raman and photoluminescence (PL) spectral analysis were performed using spectra acquired at 325 and 514 nm excitation energies. Raman analysis revealed that increase in deposition pressure from 2 to 5 Torr resulted in the transformation of the film structure from diamond-like-carbon to nanocrystalline diamond structure. UV excitation produced high PL emission intensity at 2.1 eV and the PL intensity was highest for the films deposited at the lowest pressure. Visible excitation on the other hand produced low intensity broad PL emission for all the films between 1.2 and 2.5 eV and the PL intensity was high for the films deposited at the highest deposition pressure.

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Günther, M., and G. Prokert. "A justification for the thin film approximation of Stokes flow with surface tension." Journal of Differential Equations 245, no. 10 (2008): 2802–45. http://dx.doi.org/10.1016/j.jde.2008.03.021.

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47

Hyams, D. G., and J. H. Leylek. "A Detailed Analysis of Film Cooling Physics: Part III— Streamwise Injection With Shaped Holes." Journal of Turbomachinery 122, no. 1 (1997): 122–32. http://dx.doi.org/10.1115/1.555435.

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The physics of the film cooling process for shaped, streamwise-injected, inclined jets is studied for blowing ratio (M=1.25,1.88), density ratio (DR=1.6), and length-to-diameter ratio (L/D=4) parameters typical of gas turbine operations. A previously documented computational methodology is applied for the study of five distinct film cooling configurations: (1) cylindrical film hole (reference case); (2) forward-diffused film hole; (3) laterally diffused film hole; (4) inlet shaped film hole, and (5) cusp-shaped film hole. The effect of various film hole geometries on both flow and thermal field characteristics is isolated, and the dominant mechanisms responsible for differences in these characteristics are documented. Special consideration is given to explaining crucial flow mechanisms from a vorticity point of view. It is found that vorticity analysis of the flow exiting the film hole can aid substantially in explaining the flow behavior downstream of the film hole. Results indicate that changes in the film hole shape can significantly alter the distribution of the exit-plane variables, therefore strongly affecting the downstream behavior of the film. Computational solutions of the steady, Reynolds-averaged Navier–Stokes equations are obtained using an unstructured/adaptive, fully implicit, pressure-correction solver. Turbulence closure is obtained via the high-Reynolds-number k–ε model with generalized wall functions. Detailed field results as well as surface phenomena involving adiabatic film effectiveness (η) and heat transfer coefficient (h) are presented. When possible, computational results are validated against corresponding experimental cases from data found in the open literature. Detailed comparisons are made between surface and field results of the film hole shapes investigated in this work; design criteria for optimizing downstream heat transfer characteristics are then suggested. [S0889-504X(00)01401-X]

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Shi, Yulong, Minhui Tan та X. Jiang. "Deposition of diamond/β–SiC Gradient Composite Films by Microwave Plasma-assisted Chemical Vapor Deposition". Journal of Materials Research 17, № 6 (2002): 1241–43. http://dx.doi.org/10.1557/jmr.2002.0184.

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Mixed-phase diamond/β–SiC composite films with compositional gradient were prepared by microwave plasma-assisted chemical vapor deposition using a gas mixture of hydrogen, methane and tetramethylsilane (TMS). Single-crystalline silicon wafers, pretreated with diamond nanoparticles before deposition, were used as substrates. The film characterization by scanning electron microscopy, electron probe microanalysis, and energy-dispersive x-ray analysis shows that the contents of diamond and silicon carbide in the films vary with TMS flow rate. Diamond/β–SiC composite films with compositional gradients are achievable by varying the TMS flow rate during the film growth process.

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Ismail, Farnaz, Mubashir Qayyum, and Syed Inayat Ali Shah. "Fractional Analysis of Thin Film Flow of Non-Newtonian Fluid." Computer Modeling in Engineering & Sciences 124, no. 3 (2020): 825–45. http://dx.doi.org/10.32604/cmes.2020.011073.

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AKAIKE, Osamu, Toshihiro TSUJI, and Yasutaka NAGANO. "Numerical Analysis of Cooling Air Flow in Blown Film Processing." Transactions of the Japan Society of Mechanical Engineers Series B 65, no. 633 (1999): 1737–42. http://dx.doi.org/10.1299/kikaib.65.1737.

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Journal articles on the topic 'Film flow analysis'

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