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Journal articles on the topic 'Turbulent'

Author: Grafiati

Published: 4 June 2021

Last updated: 25 July 2025

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1

Souza, José Francisco Almeida de, José Luiz Lima de Azevedo, Leopoldo Rota de Oliveira, Ivan Dias Soares, and Maurício Magalhães Mata. "TURBULENCE MODELING IN GEOPHYSICAL FLOWS – PART I – FIRST-ORDER TURBULENT CLOSURE MODELING." Revista Brasileira de Geofísica 32, no. 1 (2014): 31. http://dx.doi.org/10.22564/rbgf.v32i1.395.

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ABSTRACT. The usage of so-called turbulence closure models within hydrodynamic circulation models comes from the need to adequately describe vertical mixing processes. Even among the classical turbulence models; that is, those based on the Reynolds decomposition technique (Reynolds Averaged Navier-Stokes – RANS), there is a variety of approaches that can be followed for the modeling of turbulent flows (second moment) of momentum, heat, salinity, and other properties. Essentially, these approaches are divided into those which use the concept of turbulent viscosity/diffusivity in the modeling of

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2

Teixeira, M. A. C., and C. B. da Silva. "Turbulence dynamics near a turbulent/non-turbulent interface." Journal of Fluid Mechanics 695 (February 13, 2012): 257–87. http://dx.doi.org/10.1017/jfm.2012.17.

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AbstractThe characteristics of the boundary layer separating a turbulence region from an irrotational (or non-turbulent) flow region are investigated using rapid distortion theory (RDT). The turbulence region is approximated as homogeneous and isotropic far away from the bounding turbulent/non-turbulent (T/NT) interface, which is assumed to remain approximately flat. Inviscid effects resulting from the continuity of the normal velocity and pressure at the interface, in addition to viscous effects resulting from the continuity of the tangential velocity and shear stress, are taken into account

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Neuhaus, Lars, Daniel Ribnitzky, Michael Hölling, et al. "Model wind turbine performance in turbulent–non-turbulent boundary layer flow." Journal of Physics: Conference Series 2767, no. 4 (2024): 042018. http://dx.doi.org/10.1088/1742-6596/2767/4/042018.

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Abstract With increasing distance from the coast and greater hub heights, wind turbines expand into unknown, hardly researched environmental conditions. As height increases, laminar flow conditions become more likely. With the simultaneous increase in rotor diameter, very different flow conditions, from laminar to turbulent, occur over the rotor area. It is crucial to understand the effects of these different flow conditions on wind turbines. We approach this through wind tunnel experiments, presenting a setup with two different active grids. This setup enables the generation of four different

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4

Kadantsev, Evgeny, Evgeny Mortikov, Andrey Glazunov, Nathan Kleeorin, and Igor Rogachevskii. "On dissipation timescales of the basic second-order moments: the effect on the energy and flux budget (EFB) turbulence closure for stably stratified turbulence." Nonlinear Processes in Geophysics 31, no. 3 (2024): 395–408. http://dx.doi.org/10.5194/npg-31-395-2024.

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Abstract. The dissipation rates of the basic second-order moments are the key parameters playing a vital role in turbulence modelling and controlling turbulence energetics and spectra and turbulent fluxes of momentum and heat. In this paper, we use the results of direct numerical simulations (DNSs) to evaluate dissipation rates of the basic second-order moments and revise the energy and flux budget (EFB) turbulence closure theory for stably stratified turbulence. We delve into the theoretical implications of this approach and substantiate our closure hypotheses through DNS data. We also show w

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5

Madaliev, Murodil, Zokhidjon Abdulkhaev, Jamshidbek Otajonov, et al. "Comparison of numerical results of turbulence models for the problem of heat transfer in turbulent molasses." E3S Web of Conferences 508 (2024): 05007. http://dx.doi.org/10.1051/e3sconf/202450805007.

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The study introduces Malikov's two-fluid methodology along with the RSM turbulence model for simulating turbulent heat transfer phenomena. It elucidates that temperature fluctuations within turbulent flows arise from temperature differentials between the respective fluids. Leveraging the two-fluid paradigm, the researchers develop a mathematical framework to characterize turbulent heat transfer dynamics. This resultant turbulence model is then applied to analyze heat propagation in turbulent flows around a flat plate and in scenarios involving submerged jets. To validate the model's efficacy,

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Blair, M. F. "Boundary-Layer Transition in Accelerating Flows With Intense Freestream Turbulence: Part 2—The Zone of Intermittent Turbulence." Journal of Fluids Engineering 114, no. 3 (1992): 322–32. http://dx.doi.org/10.1115/1.2910033.

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Hot-wire anemometry was employed to examine the laminar-to-turbulent transition of low-speed, two-dimensional boundary layers for two (moderate) levels of flow acceleration and various levels of grid-generated freestream turbulence. Flows with an adiabatic wall and with uniform-flux heat transfer were explored. Conditional discrimination techniques were employed to examine the zones of flow within the transitional region. This analysis demonstrated that as much as one-half of the streamwise-component unsteadiness, and much of the apparent anisotropy, observed near the wall was produced, not by

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7

MIYAUCHI, Toshio. "Turbulence and Turbulent Combustion." TRENDS IN THE SCIENCES 19, no. 4 (2014): 4_44–4_48. http://dx.doi.org/10.5363/tits.19.4_44.

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Humphrey, Luke J., Benjamin Emerson, and Tim C. Lieuwen. "Premixed turbulent flame speed in an oscillating disturbance field." Journal of Fluid Mechanics 835 (November 27, 2017): 102–30. http://dx.doi.org/10.1017/jfm.2017.728.

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This paper considers the manner in which turbulent premixed flames respond to a superposition of turbulent and narrowband disturbances. This is an important fundamental problem that arises in most combustion applications, as turbulent flames exist in hydrodynamically unstable flow fields and/or in confined systems with narrowband acoustic waves. This paper presents the first measurements of the sensitivity of the turbulent displacement speed to harmonically oscillating flame wrinkles. The flame is attached to a transversely oscillating, heated wire, resulting in the introduction of coherent, c

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9

Xie, Aojie, Wenhui Yan та Junwei Zhou. "Calculation of a turbulent boundary layer on a flat plate using the PAFV-ω turbulence model". Journal of Physics: Conference Series 2977, № 1 (2025): 012049. https://doi.org/10.1088/1742-6596/2977/1/012049.

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Abstract To advance the creation of more efficient turbulence models and enhance the precision of numerical simulations of turbulent boundary layer flow, in this paper, based on the PAFV turbulence model and K-ω turbulence model, a new PAFV-ω turbulence model is raised, which is used for the computation of compressible fluids and requires only one empirical coefficient. A novel turbulence model was developed and numerically simulated for turbulent boundary layer flow without pressure gradient on a flat plate using the OpenFOAM software platform. Distribution patterns of mean velocity and trans

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Stamenkovic, Zivojin, Milos Kocic, and Jelena Petrovic. "The CFD modeling of two-dimensional turbulent MHD channel flow." Thermal Science 21, suppl. 3 (2017): 837–50. http://dx.doi.org/10.2298/tsci160822093s.

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In this paper, influence of magnetic field on turbulence characteristics of twodimensional flow is investigated. The present study has been undertaken to understand the effects of a magnetic field on mean velocities and turbulence parameters in turbulent 2-D channel flow. Several cases are considered. First laminar flow in a channel and MHD laminar channel flow are analyzed in order to validate model of magnetic field influence on electrically conducting fluid flow. Main part of the paper is focused on MHD turbulence suppression for 2-D turbulent flow in a channel and around the flat plate. Th

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11

Deng, Yuxin, Min Zhang, Wangqiang Jiang, and Letian Wang. "Electromagnetic Scattering of Near-Field Turbulent Wake Generated by Accelerated Propeller." Remote Sensing 13, no. 24 (2021): 5178. http://dx.doi.org/10.3390/rs13245178.

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The electromagnetic scattering study of the turbulent wake of a moving ship has important application value in target recognition and tracking. However, to date, there has been insufficient research into the electromagnetic characteristics of near-field propeller turbulence. This study presents a new procedure for evaluating the electromagnetic scattering coefficient and imaging characteristics of turbulent wakes in the near field. By controlling the different values of the net momenta, a turbulent wake was generated using the large-eddy simulation method. The results show that the net momentu

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12

Alhumairi, Mohammed, and Özgür Ertunç. "Active-grid turbulence effect on the topology and the flame location of a lean premixed combustion." Thermal Science 22, no. 6 Part A (2018): 2425–38. http://dx.doi.org/10.2298/tsci170503100a.

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Lean premixed combustion under the influence of active-grid turbulence was computationally investigated, and the results were compared with experimental data. The experiments were carried out to generate a premixed flame at a thermal load of 9 kW from a single jet flow combustor. Turbulent combustion models, such as the coherent flame model and turbulent flame speed closure model were implemented for the simulations performed under different turbulent flow conditions, which were specified by the Reynolds number based on Taylor?s microscale, the dissipation rate of turbulence, and turbulent kin

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13

Volino, R. J., and T. W. Simon. "Boundary Layer Transition Under High Free-Stream Turbulence and Strong Acceleration Conditions: Part 2—Turbulent Transport Results." Journal of Heat Transfer 119, no. 3 (1997): 427–32. http://dx.doi.org/10.1115/1.2824115.

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Measurements from heated boundary layers along a concave-curved test wall subject to high (initially 8 percent) free-stream turbulence intensity and strong (K = (ν/U∞2 dU∞/dx, as high as 9 × 10−6) acceleration are presented and discussed. Conditions for the experiments were chosen to simulate those present on the downstream half of the pressure side of a gas turbine airfoil. Turbulence statistics, including the turbulent shear stress, the turbulent heat flux, and the turbulent Prandtl number are presented. The transition zone is of extended length in spite of the high free-stream turbulence le

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Chen, Xue, Xin Luan, Dalei Song, and Hua Yang. "Multiscale Analysis of Temporal Ocean Turbulence Intermittency." Marine Technology Society Journal 53, no. 3 (2019): 54–62. http://dx.doi.org/10.4031/mtsj.53.3.7.

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AbstractAn analysis of temporal intermittency in ocean turbulent energy transfer is given. Intermittency plays a major role in ocean turbulence, and the level of intermittency strongly depends on different scales of the flow. In this work, in order to understand the temporal aspects of intermittency, we extend our research to the ocean turbulent energy transfer process. Measurements of ocean turbulence are made from a moored turbulence measuring instrument (MTMI) deployed in the South China Sea. Signals related to ocean turbulence have been collected with two orthogonal shear probes at a singl

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15

Wang, C., S. P. Oh, and M. Ruszkowski. "Turbulent heating in a stratified medium." Monthly Notices of the Royal Astronomical Society 519, no. 3 (2023): 4408–23. http://dx.doi.org/10.1093/mnras/stad003.

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ABSTRACT There is considerable evidence for widespread subsonic turbulence in galaxy clusters, most notably from Hitomi. Turbulence is often invoked to offset radiative losses in cluster cores, both by direct dissipation and by enabling turbulent heat diffusion. However, in a stratified medium, buoyancy forces oppose radial motions, making turbulence anisotropic. This can be quantified via the Froude number Fr, which decreases inward in clusters as stratification increases. We exploit analogies with MHD turbulence to show that wave–turbulence interactions increase cascade times and reduce diss

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16

Barkley, D. "Taming turbulent fronts by bending pipes." Journal of Fluid Mechanics 872 (June 4, 2019): 1–4. http://dx.doi.org/10.1017/jfm.2019.340.

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The flow of fluid through a pipe has been instrumental in illuminating the subcritical route to turbulence typical of many wall-bounded shear flows. Especially important in this process are the turbulent–laminar fronts that separate the turbulent and laminar flow. Four years ago Michael Graham (Nature, vol. 526, 2015, p. 508) wrote a commentary entitled ‘Turbulence spreads like wildfire’, which is a picturesque but also accurate characterisation of the way turbulence spreads through laminar flow in a straight pipe. In this spirit, the recent article by Rinaldi et al. (J. Fluid Mech., vol. 866,

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17

Le, Thai-Hoa, and Dong-Anh Nguyen. "TEMPORO-SPECTRAL COHERENT STRUCTURE OF TURBULENCE AND PRESSURE USING FOURIER AND WAVELET TRANSFORMS." ASEAN Journal on Science and Technology for Development 25, no. 2 (2017): 405–17. http://dx.doi.org/10.29037/ajstd.271.

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Studying the spatial distribution in coherent fields such as turbulent and turbulent-induced force ones is important to model and evaluate turbulent-induced forces and response of structures on the turbulent flows. Turbulent field-based coherent function is commonly used for the spatial distribution characteristic of induced forces in the frequency domain. This paper will focus to study spectral coherent structure of turbulence and forces in not only the frequency domain using conventional Fourier transform-based coherence, but also temporo-spectral coherent one in the time-frequency plane tha

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18

Bałdyga, J., and R. Pohorecki. "Influence of Turbulent Mechanical Stresses on Microorganisms." Applied Mechanics Reviews 51, no. 1 (1998): 121–40. http://dx.doi.org/10.1115/1.3098987.

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Many phenomena depend on the features of the fine-scale structure of turbulence, including its intermittency. This article discusses the problem of the turbulent “shear” in biotechnology including the effect of the shear stress on particles (cells, flocs, cells immobilized on microcarriers). Traditionally, the effect of intermittency has not been taken into account in the shear problem and the theory of isotropic turbulence introduced by Kolmogorov (1941) based on average values of the rate of kinetic energy dissipation, velocity fluctuactions, rates of strain, turbulent stresses etc. has been

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Vargas, Arley Cardona, Hernando Alexander Yepes Tumay, and Andrés Amell. "Experimental study of the correlation for turbulent burning velocity at subatmospheric pressure." EUREKA: Physics and Engineering, no. 4 (July 30, 2022): 25–35. http://dx.doi.org/10.21303/2461-4262.2022.002414.

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Turbulent burning velocity is one of the most relevant parameters to characterize the premixed turbulent flames. Different correlation has been proposed to estimate this parameter. However, most of them have been obtained using experimental data at atmospheric pressure or higher. The present study is focused on obtaining a correlation for the turbulent burning velocity using data at sub-atmospheric pressure. The turbulent burning velocity was experimentally calculated using the burner method, where turbulent premix flames are generated in a Bunsen burner. Stoichiometric and lean conditions wer

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20

Ansorge, Cedrick, and Juan Pedro Mellado. "Analyses of external and global intermittency in the logarithmic layer of Ekman flow." Journal of Fluid Mechanics 805 (September 23, 2016): 611–35. http://dx.doi.org/10.1017/jfm.2016.534.

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Existence of non-turbulent flow patches in the vicinity of the wall of a turbulent flow is known as global intermittency. Global intermittency challenges the conventional statistics approach when describing turbulence in the inner layer and calls for the use of conditional statistics. We extend the vorticity-based conditioning of a flow to turbulent and non-turbulent sub-volumes by a high-pass filter operation. This modified method consistently detects non-turbulent flow patches in the outer and inner layers for stratifications ranging from the neutral limit to extreme stability, where the flo

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Vargas, Arley Cardona, Hernando Alexander Yepes Tumay, and Andrés Amell. "Experimental study of the correlation for turbulent burning velocity at subatmospheric pressure." EUREKA: Physics and Engineering, no. 4 (July 30, 2022): 25–35. https://doi.org/10.21303/2461-4262.2022.002414.

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Turbulent burning velocity is one of the most relevant parameters to characterize the premixed turbulent flames. Different correlation has been proposed to estimate this parameter. However, most of them have been obtained using experimental data at atmospheric pressure or higher. The present study is focused on obtaining a correlation for the turbulent burning velocity using data at sub-atmospheric pressure. The turbulent burning velocity was experimentally calculated using the burner method, where turbulent premix flames are generated in a Bunsen burner. Stoichiometric and lean conditions wer

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22

Arró, G., F. Califano, and G. Lapenta. "Statistical properties of turbulent fluctuations associated with electron-only magnetic reconnection." Astronomy & Astrophysics 642 (October 2020): A45. http://dx.doi.org/10.1051/0004-6361/202038696.

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Context. Recent satellite measurements in the turbulent magnetosheath of Earth have given evidence of an unusual reconnection mechanism that is driven exclusively by electrons. This newly observed process was called electron-only reconnection, and its interplay with plasma turbulence is a matter of great debate. Aims. By using 2D-3V hybrid Vlasov–Maxwell simulations of freely decaying plasma turbulence, we study the role of electron-only reconnection in the development of plasma turbulence. In particular, we search for possible differences with respect to the turbulence associated with standar

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Zhu, Yunzhou, Huan Nie, Qian Liu, Yi Yang, and Jianlei Zhang. "Research on the Use of an Ocean Turbulence Bubble Simulation Model to Analyze Wireless Optical Transmission Characteristics." Electronics 13, no. 13 (2024): 2626. http://dx.doi.org/10.3390/electronics13132626.

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Turbulent vortices with uneven refractive indices and sizes affect the transmission quality of laser beams in seawater, diminishing the performance of underwater wireless optical communication systems. Currently, the phase screen simulation model constrains the range of turbulent vortex scales that can be analyzed, and the mutual restrictions of the phase screen parameters are not suitable for use on large-scale turbulent vortices. Referring to the formation process of turbulent vortices based on Kolmogorov’s turbulence structure energy theory, this study abstractly models the process and simu

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Jacobitz, Frank G., Kai Schneider, Wouter J. T. Bos, and Marie Farge. "On helical multiscale characterization of homogeneous turbulence." Journal of Turbulence 13 (January 1, 2012): N35. https://doi.org/10.1080/14685248.2012.711476.

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The helical properties of five prototypical homogeneous turbulent flows are investigated: statistically steady forced isotropic turbulence, decaying isotropic turbulence, decaying rotating turbulence, growing sheared turbulence, and growing rotating sheared turbulence with a rotation ratio f/S=+0.5. The five turbulent flows were originally studied using direct numerical simulations, and well-developed flow fields are chosen for this analysis. For comparison, a solenoidal uncorrelated Gaussian random field is included in the analysis as a sixth case. An orthogonal wavelet decomposition is used

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Wang, Zhenchuan, Guoli Qi, and Meijun Li. "Discussion on improved method of turbulence model for supercritical water flow and heat transfer." Thermal Science 24, no. 5 Part A (2020): 2729–41. http://dx.doi.org/10.2298/tsci190813007w.

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The turbulence model fails in supercritical fluid-flow and heat transfer simulation, owing to the drastic change of thermal properties. The inappropriate buoyancy effect model and the improper turbulent Prandtl number model are several of these factors lead to the original low-Reynolds number turbulence model unable to predict the wall temperature for vertically heated tubes under the deteriorate heat transfer conditions. This paper proposed a simplified improved method to modify the turbulence model, using the generalized gradient diffusion hypothesis approximation model for the production te

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Nagaoka, Hiroshi, and Katsuyuki Sugio. "Effect of turbulent structure on filament-type biofilm reaction." Water Science and Technology 30, no. 11 (1994): 111–20. http://dx.doi.org/10.2166/wst.1994.0551.

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Effect of turbulent diffusion on substrate uptake rate by biofilms was studied. A new turbulent diffusion biofilm model was developed considering profiles of turbulent diffusivity in and over biofilms. A numerical simulation was conducted using a proposed model to show that substrate flux changes with turbulent diffusivity obeying a power law with the coefficient value between 0 and 1. Biofilm was grown in open channels and the effect of short-term changes in turbulence of the overlying flow on substrate flux into the biofilm was measured. Profiles of velocity and turbulent intensity in the ov

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Folorunso, OP. "Turbulent Kinetic Energy and Budget of Heterogeneous Open Channel with Gravel and Vegetated Beds." Journal of Civil Engineering Research & Technology 3, no. 2 (2021): 1–4. http://dx.doi.org/10.47363/jcert/2021(3)115.

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Turbulent kinetic energy (TKE) and budget are indispensable hydraulic parameters to determine turbulent scales and processes resulting from various and different natural hydraulic features in open channels. This paper focuses on experimental investigation of turbulent kinetic energy and budget in a heterogeneous open channel flow with gravel and vegetated beds. Results indicate the turbulent kinetic energy (TKE) value over gravel region of the heterogeneous bed remains approximately constant with flow depth. The highest turbulent kinetic energy was calculated for flexible vegetation arrangemen

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Ren, Yan, Hongsheng Zhang, Xiaoye Zhang, et al. "Quantitative verification of the turbulence barrier effect during heavy haze pollution events." Environmental Research Communications 4, no. 4 (2022): 045005. http://dx.doi.org/10.1088/2515-7620/ac6381.

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Abstract Under calm and steady weather conditions with low wind speeds, turbulent intermittency frequently occurs in the atmospheric boundary layer (ABL), which can significantly weaken the turbulent diffusion of matter and energy between the surface and atmosphere. The turbulence barrier effect is defined as the phenomenon in which turbulence may disappear at certain heights, and during periods of heavy haze, creating what can seem like a barrier layer that hinders vertical transmissions. Although the turbulence barrier effect can explain the physical mechanisms behind the rapid accumulation

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Oluwadare, Benjamin Segun, Paul Chukwulozie Okolie, David Ojo Akindele, Oluwafemi Festus Olaiyapo, Ayobami Phillip Akinsipe, and Oku Ekpenyong Nyong. "Transition to Turbulence of a Laminar Flow Accelerated to a Statistically Steady Turbulent Flow." European Journal of Theoretical and Applied Sciences 2, no. 3 (2024): 430–45. http://dx.doi.org/10.59324/ejtas.2024.2(3).34.

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This current study investigates the turbulence response in a flow accelerated from laminar to a statistically steady turbulent flow utilising Particle Image Velocimetry (PIV) and Constant Temperature Anemometry (CTA). The dimensions of the rectangular flow facility are 8 m in length, 0.35 m in width, and 0.05 m in height. The flow is increased via the pneumatic control valve from a laminar to a statistically steady turbulent flow, and the laminar-turbulent transition is examined. As the flow accelerates to turbulent from laminar, the friction coefficient increases quickly and approaches its ma

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Oluwadare, Benjamin Segun, Paul Chukwulozie Okolie, David Ojo Akindele, Oluwafemi Festus Olaiyapo, Ayobami Phillip Akinsipe, and Oku Ekpenyong Nyong. "Transition to Turbulence of a Laminar Flow Accelerated to a Statistically Steady Turbulent Flow." European Journal of Theoretical and Applied Sciences 2, no. 2 (2024): 928–43. http://dx.doi.org/10.59324/ejtas.2024.2(2).82.

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This current study investigates the turbulence response in a flow accelerated from laminar to a statistically steady turbulent flow utilising Particle Image Velocimetry (PIV) and Constant Temperature Anemometry (CTA). The dimensions of the rectangular flow facility are 8 m in length, 0.35 m in width, and 0.05 m in height. The flow is increased via the pneumatic control valve from a laminar to a statistically steady turbulent flow, and the laminar-turbulent transition is examined. As the flow accelerates to turbulent from laminar, the friction coefficient increases quickly and approaches its ma

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Benjamin, Segun Oluwadare, Chukwulozie Okolie Paul, Ojo Akindele David, Festus Olaiyapo Oluwafemi, Phillip Akinsipe Ayobami, and Ekpenyong Nyong Oku. "Transition to Turbulence of a Laminar Flow Accelerated to a Statistically Steady Turbulent Flow." European Journal of Theoretical and Applied Sciences 2, no. 2 (2024): 928–43. https://doi.org/10.59324/ejtas.2024.2(2).82.

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This current study investigates the turbulence response in a flow accelerated from laminar to a statistically steady turbulent flow utilising Particle Image Velocimetry (PIV) and Constant Temperature Anemometry (CTA). The dimensions of the rectangular flow facility are 8 m in length, 0.35 m in width, and 0.05 m in height. The flow is increased via the pneumatic control valve from a laminar to a statistically steady turbulent flow, and the laminar-turbulent transition is examined. As the flow accelerates to turbulent from laminar, the friction coefficient increases quickly and approaches its ma

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Gao, Ge, and Huang Ning. "A New Theory for Solving Turbulent Vortices in Flowing Fluids." Journal of Engineering for Gas Turbines and Power 108, no. 2 (1986): 259–64. http://dx.doi.org/10.1115/1.3239897.

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Turbulent vortices occur everywhere in flowing fluids and possess the properties of dissipation and dispersion. A set of new control equations is presented featuring the interaction between dissipation and dispersion of turbulence. By analysis of instability the rate of turbulent energy production is established. Two third-order derivative momentum equations are derived, one for weak and the other for strong vorticity. By this new theory various turbulent flow problems can be solved, such as: energy inversion in the vortex tail behind a bluff body, the coherent horseshoe vortices in a turbulen

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Käpylä, P. J., M. Rheinhardt, A. Brandenburg, and M. J. Käpylä. "Turbulent viscosity and magnetic Prandtl number from simulations of isotropically forced turbulence." Astronomy & Astrophysics 636 (April 2020): A93. http://dx.doi.org/10.1051/0004-6361/201935012.

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Context. Turbulent diffusion of large-scale flows and magnetic fields plays a major role in many astrophysical systems, such as stellar convection zones and accretion discs. Aims. Our goal is to compute turbulent viscosity and magnetic diffusivity which are relevant for diffusing large-scale flows and magnetic fields, respectively. We also aim to compute their ratio, which is the turbulent magnetic Prandtl number, Pmt, for isotropically forced homogeneous turbulence. Methods. We used simulations of forced turbulence in fully periodic cubes composed of isothermal gas with an imposed large-scale

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Watanabe, Tomoaki, Carlos B. da Silva, and Koji Nagata. "Non-dimensional energy dissipation rate near the turbulent/non-turbulent interfacial layer in free shear flows and shear free turbulence." Journal of Fluid Mechanics 875 (July 18, 2019): 321–44. http://dx.doi.org/10.1017/jfm.2019.462.

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The non-dimensional dissipation rate $C_{\unicode[STIX]{x1D700}}=\unicode[STIX]{x1D700}L/u^{\prime 3}$, where $\unicode[STIX]{x1D700}$, $L$ and $u^{\prime }$ are the viscous energy dissipation rate, integral length scale of turbulence and root-mean-square of the velocity fluctuations, respectively, is computed and analysed within the turbulent/non-turbulent interfacial (TNTI) layer using direct numerical simulations of a planar jet, mixing layer and shear free turbulence. The TNTI layer that separates the turbulent and non-turbulent regions exists at the edge of free shear turbulent flows and

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Kozioł, Adam, Janusz Urbański, Adam Kiczko, Marcin Krukowski, and Piotr Siwicki. "Turbulent intensity and scales of turbulence after hydraulic jump in rectangular channel." Annals of Warsaw University of Life Sciences – SGGW. Land Reclamation 48, no. 2 (2016): 99–109. http://dx.doi.org/10.1515/sggw-2016-0008.

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Abstract Turbulent intensity and scales of turbulence after hydraulic jump in rectangular channel. Experimental research was undertaken to investigate the changes in spatial turbulence intensity and scales of turbulent eddies (macroeddies) in a rectangular channel and the influence of the hydraulic jump on vertical, lateral and streamwise distributions of relative turbulence intensity and scales of turbulent eddies. The results of three tests for different discharges are presented. An intensive turbulent mixing that arises as a result of a hydraulic jump has a significant effect on instantaneo

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Mauritsen, Thorsten, Gunilla Svensson, Sergej S. Zilitinkevich, Igor Esau, Leif Enger, and Branko Grisogono. "A Total Turbulent Energy Closure Model for Neutrally and Stably Stratified Atmospheric Boundary Layers." Journal of the Atmospheric Sciences 64, no. 11 (2007): 4113–26. http://dx.doi.org/10.1175/2007jas2294.1.

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Abstract This paper presents a turbulence closure for neutral and stratified atmospheric conditions. The closure is based on the concept of the total turbulent energy. The total turbulent energy is the sum of the turbulent kinetic energy and turbulent potential energy, which is proportional to the potential temperature variance. The closure uses recent observational findings to take into account the mean flow stability. These observations indicate that turbulent transfer of heat and momentum behaves differently under very stable stratification. Whereas the turbulent heat flux tends toward zero

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Ezato, K., A. M. Shehata, T. Kunugi, and D. M. McEligot. "Numerical Prediction of Transitional Features of Turbulent Forced Gas Flows in Circular Tubes With Strong Heating." Journal of Heat Transfer 121, no. 3 (1999): 546–55. http://dx.doi.org/10.1115/1.2826015.

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In order to treat strongly heated, forced gas flows at low Reynolds numbers in vertical circular tubes, the k-ε turbulence model of Abe, Kondoh, and Nagano (1994), developed for forced turbulent flow between parallel plates with the constant property idealization, has been successfully applied. For thermal energy transport, the turbulent Prandtl number model of Kays and Crawford (1993) was adopted. The capability to handle these flows was assessed via calculations at the conditions of experiments by Shehata (1984), ranging from essentially turbulent to laminarizing due to the heating. Predicti

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Jin, Y., M. F. Uth, A. V. Kuznetsov, and H. Herwig. "Numerical investigation of the possibility of macroscopic turbulence in porous media: a direct numerical simulation study." Journal of Fluid Mechanics 766 (February 2, 2015): 76–103. http://dx.doi.org/10.1017/jfm.2015.9.

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AbstractWhen a turbulent flow in a porous medium is determined numerically, the crucial question is whether turbulence models should account only for turbulent structures restricted in size to the pore scale or whether the size of turbulent structures could exceed the pore scale. The latter would mean the existence of macroscopic turbulence in porous media, when turbulent eddies exceed the pore size. In order to determine the real size of turbulent structures in a porous medium, we simulated the turbulent flow by direct numerical simulation (DNS) calculations, thus avoiding turbulence modellin

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Jovanović, J., M. Pashtrapanska, B. Frohnapfel, F. Durst, J. Koskinen, and K. Koskinen. "On the Mechanism Responsible for Turbulent Drag Reduction by Dilute Addition of High Polymers: Theory, Experiments, Simulations, and Predictions." Journal of Fluids Engineering 128, no. 1 (2005): 118–30. http://dx.doi.org/10.1115/1.2073227.

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Turbulent drag reduction by dilute addition of high polymers is studied by considering local stretching of the molecular structure of a polymer by small-scale turbulent motions in the region very close to the wall. The stretching process is assumed to restructure turbulence at small scales by forcing these to satisfy local axisymmetry with invariance under rotation about the axis aligned with the main flow. It can be shown analytically that kinematic constraints imposed by local axisymmetry force turbulence near the wall to tend towards the one-component state and when turbulence reaches this

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Liu, Zhenchen, Peiqing Liu, Hao Guo, and Tianxiang Hu. "Experimental investigations of turbulent decaying behaviors in the core-flow region of a propeller wake." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 234, no. 2 (2019): 319–29. http://dx.doi.org/10.1177/0954410019865702.

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This work investigates the turbulent decaying behaviors downstream of a propeller in the core-flow region. Both axial and tangential velocity fluctuations behind a two-bladed propeller were measured using a stationary hot-wire probe. Unexpectedly, the complex near-wake core-flow of the propeller is found to show a similar decay characteristic of homogeneous turbulence, such as grid turbulence. The decay of turbulence intensity is found to be dominated by the level of periodic velocity fluctuations, showing a similar behavior of the homogenous and isotropic turbulence. This turbulent decaying b

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Buice, C. U., and J. K. Eaton. "Turbulent Heat Transport in a Perturbed Channel Flow." Journal of Heat Transfer 121, no. 2 (1999): 322–25. http://dx.doi.org/10.1115/1.2825983.

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The recovering boundary layer downstream of a separation bubble is known to have a highly perturbed turbulence structure which creates difficulty for turbulence models. The present experiment addressed the effect of this perturbed structure on turbulent heat transport. The turbulent diffusion of heat downstream of a heated wire was measured in a perturbed channel flow and compared to that in a simple, fully developed channel flow. The turbulent diffusivity of heat was found to be more than 20 times larger in the perturbed flow. The turbulent Prandtl number increased to 1.7, showing that the tu

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Ruan, W., L. Yan, and R. Keppens. "Magnetohydrodynamic Turbulence Formation in Solar Flares: 3D Simulation and Synthetic Observations." Astrophysical Journal 947, no. 2 (2023): 67. http://dx.doi.org/10.3847/1538-4357/ac9b4e.

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Abstract Turbulent plasma motion is common in the universe and invoked in solar flares to drive effective acceleration leading to high-energy electrons. Unresolved mass motions are frequently detected in flares from extreme ultraviolet (EUV) observations, which are often regarded as turbulence. However, how this plasma turbulence forms during the flare is still largely a mystery. Here we successfully reproduce observed turbulence in our 3D magnetohydrodynamic simulation where the magnetic reconnection process is included. The turbulence forms as a result of an intricate nonlinear interaction b

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Gu, Jie, Xiao Li Wang, Wei Chen, Xin Qin, Dan Qing Ma, and Ji Zhong Yang. "Numerical Analysis of the Influence of Different-Shaped Square Cylinders on Water Flow." Advanced Materials Research 614-615 (December 2012): 604–7. http://dx.doi.org/10.4028/www.scientific.net/amr.614-615.604.

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A 3D numerical model was performed to simulate the different cases of the water flow across different-shaped square cylinders. Figures of streamlines and turbulent kinetic energy contour lines in different cases were obtained. Through the comparison of streamlines, the areas of strong turbulent kinetic energy and the strongest turbulent kinetic energy nucleus, the results indicated that,(i) two symmetrical vortexes were formed behind the regular quadrilateral square cylinder and the “⊥”-shaped square cylinder ,respectively, and the former were bigger than the latter .While the flow crossed the

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Saeid, Nawaf H. "USING TWO TIME SCALES OF TURBULENCE FOR BOUNDARY LAYER FLOWS." ASEAN Journal on Science and Technology for Development 19, no. 2 (2017): 45–55. http://dx.doi.org/10.29037/ajstd.337.

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A near wall improvement of the k-ε model of turbulence is proposed and evaluated. The present model takes into account the asymptotic behavior of turbulent scales near wall region and for free turbulence region. The Kolmogorov turbulent time scale is introduced as a lower limit. The model is used for prediction of turbulent boundary layer flows. Predictions compared with experimental data of several flow cases, with encouraging results.

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Marxen, Olaf, and Tamer A. Zaki. "Turbulence in intermittent transitional boundary layers and in turbulence spots." Journal of Fluid Mechanics 860 (December 5, 2018): 350–83. http://dx.doi.org/10.1017/jfm.2018.822.

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Direct numerical simulation data of bypass transition in flat-plate boundary layers are analysed to examine the characteristics of turbulence in the transitional regime. When intermittency is 50 % or less, the flow features a juxtaposition of turbulence spots surrounded by streaky laminar regions. Conditionally averaged turbulence statistics are evaluated within the spots, and are compared to standard time averaging in both the transition region and in fully turbulent boundary layers. The turbulent-conditioned root-mean-square levels of the streamwise velocity perturbations are notably elevate

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Meinecke, Jena, Petros Tzeferacos, Anthony Bell, et al. "Developed turbulence and nonlinear amplification of magnetic fields in laboratory and astrophysical plasmas." Proceedings of the National Academy of Sciences 112, no. 27 (2015): 8211–15. http://dx.doi.org/10.1073/pnas.1502079112.

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The visible matter in the universe is turbulent and magnetized. Turbulence in galaxy clusters is produced by mergers and by jets of the central galaxies and believed responsible for the amplification of magnetic fields. We report on experiments looking at the collision of two laser-produced plasma clouds, mimicking, in the laboratory, a cluster merger event. By measuring the spectrum of the density fluctuations, we infer developed, Kolmogorov-like turbulence. From spectral line broadening, we estimate a level of turbulence consistent with turbulent heating balancing radiative cooling, as it li

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Sumiadi, Sumiadi. "DISTRIBUSI INTESITAS TURBULEN PADA BELOKAN SALURAN DENGAN DASAR TERGERUS." Gorontalo Journal of Infrastructure and Science Engineering 4, no. 1 (2021): 1. http://dx.doi.org/10.32662/gojise.v4i1.1356.

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The flow characteristics on the channel bend are very complex. The Centrifugal force causes an increase in secondary flow. Increased secondary flow triggers changes in the channel bed topography. This phenomenon is very possible to change the flow structure including turbulent intensity. This research aims to determine the distribution of turbulent intensity at eroded-bed channel bend and to compare whether the equations of the turbulent intensity distribution by Nezu (1977) are still valid. This research was conducted at the Hydraulic Laboratory using 180° curved open channels. The bed materi

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Zhao, Hanqing, Jing Yan, Saiyu Yuan, Jiefu Liu, and Jinyu Zheng. "Effects of Submerged Vegetation Density on Turbulent Flow Characteristics in an Open Channel." Water 11, no. 10 (2019): 2154. http://dx.doi.org/10.3390/w11102154.

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The vegetation density λ affects turbulent flow type in the submerged vegetated river. This laboratory study investigates different types of vegetated turbulent flow, especially the flow at 0.04 < λ < 0.1 and λ = 1.44 by setting the experimental λ within a large range. Vertical distributions of turbulent statistics (velocity, shear stress and skewness coefficients), turbulence kinetic generation rate and turbulence spectra in different λ conditions have been presented and compared. Results indicate that for flow at 0.04 < λ < 0.1, the profiles of turbulent statistics manifest chara

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Mohmmed Ahmed, Osman Abu Bakr, and Mark Ovinis. "EVALUATION OF K-EPSILON MODEL FOR TURBULENT BUOYANT JET." Platform : A Journal of Engineering 3, no. 2 (2019): 55. http://dx.doi.org/10.61762/pajevol3iss2art5085.

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The modelling of a turbulent buoyant jet is challenging due to the complex nature of such flow, which consists of two fluids with different densities, as well as the multi-scale flow phenomena associated in both space and time. In this paper, the k-epsilon turbulence model is applied to model a turbulent buoyant jet at different flow regimes including laminar and turbulent. The velocity field and centerline velocity are in good agreement with the experiments, as well as the expected results based on jet theory. Moreover, the distribution of the radial velocity matches with Gaussian distributio

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Kawata, Takuya, and Takahiro Tsukahara. "Spectral Analysis on Transport Budgets of Turbulent Heat Fluxes in Plane Couette Turbulence." Energies 15, no. 14 (2022): 5258. http://dx.doi.org/10.3390/en15145258.

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In recent years, scale-by-scale energy transport in wall turbulence has been intensively studied, and the complex spatial and interscale transfer of turbulent energy has been investigated. As the enhancement of heat transfer is one of the most important aspects of turbulence from an engineering perspective, it is also important to study how turbulent heat fluxes are transported in space and in scale by nonlinear multi-scale interactions in wall turbulence as well as turbulent energy. In the present study, the spectral transport budgets of turbulent heat fluxes are investigated based on direct

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