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We present various Lattice Boltzmann Models which reproduce the effects of rough walls, shear thinning and granular flow. We examine the boundary layers generated by the roughness of the walls. Shear thinning produces plug flow with a sharp…

Condensed Matter · Physics 2009-10-22 E. G. Flekkoy , H. J. Herrmann

First principle based prediction of mean flow quantities of wall-bounded turbulent flows (channel, pipe, and turbulent boundary layer - TBL) is of great importance from both physics and engineering standpoints. Here (Part I), we present a…

Fluid Dynamics · Physics 2015-05-12 Zhen-Su She , Xi Chen , Fazle Hussain

The energy pathways from propagating internal waves to the scales of irreversible mixing in the ocean are not fully described. In the ocean interior, the triadic resonant instability is an intrinsic destabilization process that may enhance…

Fluid Dynamics · Physics 2021-02-10 Yvan Dossmann , Florence Pollet , Philippe Odier , Thierry Dauxois

We investigate a mechanism to manipulate wall-bounded flows whereby wave-like undulations of the wall topography drives the creation of bespoke longitudinal vortices. A resonant interaction between the ambient vorticity of the undisturbed…

Fluid Dynamics · Physics 2020-08-10 Andreas H. Akselsen , Simen Å. Ellingsen

Field and laboratory measurements of suspended sediments over wave ripples show, for time-averaged concentration profiles in semi-log plots, a contrast between upward convex profiles for fine sand and upward concave profiles for coarse…

Fluid Dynamics · Physics 2010-11-30 Rafik Absi

A mathematical model that governs turbulent flows through permeable media is considered in this work. The model under consideration is based on a double-averaging concept which in turn is described by the time-averaging technique…

Analysis of PDEs · Mathematics 2024-03-26 Hermenegildo Borges de Oliveira

Turbulent mixing and entrainment at the boundary of a cloud is studied by means of direct numerical simulations that couple the Eulerian description of the turbulent velocity and water vapor fields with a Lagrangian ensemble of cloud water…

Fluid Dynamics · Physics 2013-10-14 Bipin Kumar , Joerg Schumacher , Raymond A. Shaw

In the present study, we conduct direct numerical simulations of two-way force-coupled particle-laden compressible turbulent boundary layers at the free-stream Mach number of 2.0 for the purpose of examining the effects of particles on the…

Fluid Dynamics · Physics 2024-07-01 Ming Yu , Yibin Du , Qian Wang , Siwei Dong , Xianxu Yuan

In rough-wall boundary layers, wall-parallel non-homogeneous mean-flow solutions exist that lead to so-called dispersive velocity components and dispersive stresses. They play a significant role in the mean-flow momentum balance near the…

Fluid Dynamics · Physics 2019-02-20 Johan Meyers , Bharathram Ganapathisubramani , Raúl Bayoán Cal

We present an approach to turbulence closure based on mixing length theory with three-dimensional fluctuations against a two-dimensional background. This model is intended to be rapidly computable for implementation in stellar evolution…

Solar and Stellar Astrophysics · Physics 2018-09-28 Adam S. Jermyn , Pierre Lesaffre , Christopher A. Tout , Shashikumar M. Chitre

We present the results of a Direct Numerical Simulation of a particle-laden spatially developing turbulent boundary layer up to Re{\theta} = 2500. Two main features differentiate the behavior of inertial particles in a zero-…

The pressure gradient has a significant influence on the mean-flow properties of turbulent boundary layers. Conventional analytical studies on PG turbulent boundary layers are conducted separately for the viscous sub-layer and overlap layer…

Fluid Dynamics · Physics 2024-09-10 Tan-Tan Du , Jun Chen , Wei-Tao Bi , Zhen-Su She

(Abridged) We describe the results of three-dimensional (3D) numerical simulations designed to study turbulent convection in the stellar interiors, and compare them to stellar mixing-length theory (MLT). Simulations in 2D are significantly…

Astrophysics · Physics 2011-02-11 Casey A. Meakin , David Arnett

We investigate the effect that the turbulent mixing strength parameter $\alpha_{\rm{turb}}$ plays on near-infrared polarimetric and sub-millimetre interferometric imaging observations of transitional discs (TDs) with a gap carved by a…

Solar and Stellar Astrophysics · Physics 2016-04-01 M. de Juan Ovelar , P. Pinilla , M. Min , C. Dominik , T. Birnstiel

Thwaites (1949) developed an approximate method for determining the evolution of laminar boundary layers. The approximation follows from an assumption that the growth of a laminar boundary layer in the presence of pressure gradients could…

Fluid Dynamics · Physics 2023-10-26 Rahul Agrawal , Sanjeeb T. Bose , Kevin P. Griffin , Parviz Moin

Boundary layer flow over a realistic porous wall might contain both the effects of wall-permeability and wall-roughness. These two effects are typically examined in the context of a rough-wall flow, i.e., by defining a ``roughness'' length…

Fluid Dynamics · Physics 2023-07-26 D. D. Wangsawijaya , P. Jaiswal , B. Ganapathisubramani

We report detailed quantitative studies of elastic turbulence in a curvilinear channel flow in a dilute polymer solution of high molecular weight polyacrylamide in a high viscosity water-sugar solvent. Detailed studies of the average and…

Chaotic Dynamics · Physics 2015-05-30 Yonggun Jun , Victor Steinberg

Turbulent boundary layers exhibit a universal structure which nevertheless is rather complex, being composed of a viscous sub-layer, a buffer zone, and a turbulent log-law region. In this letter we present a simple analytic model of…

Chaotic Dynamics · Physics 2007-05-23 Victor S. L'vov , Itamar Procaccia , Oleksii Rudenko

We consider four turbulent models to simulate the boundary mixing layer of the ocean. We show the existence of solutions to these models in the steady-state case then we study the mathematical stability of these solutions.

Mathematical Physics · Physics 2016-08-16 Anne-Claire Bennis , Tomás Chacón Rebollo , Macarena Gomez Marmol , Roger Lewandowski

Direct numerical simulations of turbulent Taylor-Couette flow are performed up to inner cylinder Reynolds numbers of {Re_i=10^5} for a radius ratio of {\eta=r_i/r_o=0.714} between the inner and outer cylinder. With increasing {Re_i}, the…