scholarly journals Turbulent closure analysis in heated separated and reattached flow using eddy-resolving data

2020 ◽  
Vol 32 (4) ◽  
pp. 045115 ◽  
Author(s):  
Christopher D. Ellis
Keyword(s):  
Turbulent Closure ◽  
Separated And Reattached Flow

Simulation and Modeling of Turbulent Flows

1996 ◽  
Keyword(s):  
Numerical Simulation ◽  
Turbulent Flow ◽  
Turbulent Flows ◽  
Simulation And Modeling ◽  
Simulation Techniques ◽  
Rational Development ◽  
Group Methods ◽  
Turbulent Closure ◽  
The Subject ◽  
Renormalization Group Methods

This book provides students and researchers in fluid engineering with an up-to-date overview of turbulent flow research in the areas of simulation and modeling. A key element of the book is the systematic, rational development of turbulence closure models and related aspects of modern turbulent flow theory and prediction. Starting with a review of the spectral dynamics of homogenous and inhomogeneous turbulent flows, succeeding chapters deal with numerical simulation techniques, renormalization group methods and turbulent closure modeling. Each chapter is authored by recognized leaders in their respective fields, and each provides a thorough and cohesive treatment of the subject.

LES of Turbulent Separated Flow and Heat Transfer in a Symmetric Expansion Plane Channel

2005 ◽  
Vol 127 (5) ◽  
pp. 865-871 ◽  
Author(s):  
Kazuaki Sugawara ◽  
Hiroyuki Yoshikawa ◽  
Terukazu Ota
Keyword(s):  
Heat Transfer ◽  
Finite Difference ◽  
Plane Channel ◽  
Separated Flow ◽  
Expansion Ratio ◽  
Vortical Flow ◽  
Flow And Heat Transfer ◽  
Finite Difference Equations ◽  
Separated And Reattached Flow ◽  
Fundamental Equations

The LES method was applied to analyze numerically an unsteady turbulent separated and reattached flow and heat transfer in a symmetric expansion plane channel of expansion ratio 2.0. The Smagorinsky model was used in the analysis and fundamental equations were discretized by means of the finite difference method, and their resulting finite difference equations were solved using the SMAC method. The calculations were conducted for Re=15,000. It is found that the present numerical results, in general, agree well with the previous experimental ones. The complicated vortical flow structures in the channel and their correlations with heat transfer characteristics are visualized through various fields of flow quantities.

Barotropic theory for the velocity profile of Jupiter’s turbulent jets: an example for an exact turbulent closure

2018 ◽  
Vol 860 ◽  
pp. 577-607
Author(s):  
E. Woillez ◽  
F. Bouchet
Keyword(s):  
Velocity Profile ◽  
Turbulent Jets ◽  
Equilibrium Structure ◽  
Injection Rate ◽  
Velocity Shear ◽  
Small Scale ◽  
Reynolds Stresses ◽  
Zonal Jets ◽  
Time Scale Separation ◽  
Turbulent Closure

We model the dynamics of Jupiter’s jets by the stochastic barotropic $\unicode[STIX]{x1D6FD}$-plane model. In this simple framework, by analytic computation of the averaged effect of eddies, we obtain three new explicit results about the equilibrium structure of jets. First we obtain a very simple explicit relation between the Reynolds stresses, the energy injection rate and the averaged velocity shear. This predicts the averaged velocity profile far from the jet edges (extrema of zonal velocity). Our approach takes advantage of a time-scale separation between the inertial dynamics on one hand, and the spin-up (or spin-down) time on the other. Second, a specific asymptotic expansion close to the eastward jet extremum explains the formation of a cusp at the scale of energy injection, characterized by a curvature that is independent of the forcing spectrum. Finally, we derive equations that describe the evolution of the westward tip of the jets. The analysis of these equations is consistent with the previously discussed picture of barotropic adjustment, explaining the relation between the westward jet curvature and the $\unicode[STIX]{x1D6FD}$-effect. Our results give a consistent overall theory of the stationary velocity profile of inertial barotropic zonal jets, in the limit of small-scale forcing.

scholarly journals Numerical modeling of blowing and drifting snow in Alpine terrain

2001 ◽  
Vol 47 (156) ◽  
pp. 97-110 ◽  
Author(s):  
Peter Gauer
Keyword(s):  
Field Measurements ◽  
Erosion And Deposition ◽  
Mountainous Regions ◽  
Boundary Layer Equations ◽  
Trajectory Calculations ◽  
Drifting Snow ◽  
Physically Based ◽  
Turbulent Closure ◽  
Snow Distribution ◽  
Two Layer Model

AbstractIn mountainous regions, snow transport due to wind significantly influences snow distribution and, as a result, avalanche danger. A physically based numerical two-layer model is developed to simulate blowing and drifting snow in Alpine terrain. One layer describes the driving-wind field and the transport in suspension. The description is based on the atmospheric boundary-layer equations, using ane−∊model for the turbulent closure. The second layer describes the transport due to saltation, including erosion and deposition of snow. Here, conservation equations for mass and momentum are formulated for the mixture of snow and air. Particle trajectory calculations are used to parameterize quantities characterizing the saltation layer. Both layers are mutually coupled by boundary conditions. A two-way coupling between particles and airflow is taken into account. Comparisons between simulation results and field measurements around an Alpine crest show encouraging results.

Invariance of turbulent closure models

1979 ◽  
Vol 22 (6) ◽  
pp. 1033 ◽  
Author(s):  
Charles G. Speziale
Keyword(s):  
Closure Models ◽  
Turbulent Closure

LES of Turbulent Separated Flow and Heat Transfer in a Symmetric Expansion Plane Channel

2004 ◽  
Author(s):  
Kazuaki Sugawara ◽  
Hiroyuki Yoshikawa ◽  
Terukazu Ota
Keyword(s):  
Heat Transfer ◽  
Finite Difference ◽  
Plane Channel ◽  
Separated Flow ◽  
Expansion Ratio ◽  
Vortical Flow ◽  
Flow And Heat Transfer ◽  
Finite Difference Equations ◽  
Separated And Reattached Flow ◽  
Fundamental Equations

LES method is applied to simulate numerically a turbulent separated and reattached flow and heat transfer in a symmetric expansion plane channel of expansion ratio 2.0. Smagorinsky model is used in the analysis and fundamental equations are discretized by means of the finite difference method, and their resulting finite difference equations are solved using SMAC method. The calculations are conducted for Re = 15000. It is found that the present numerical results, in general, agree well with the previous experimental ones. The complicated vortical flow structures in the channel and their correlations with heat transfer characteristics are visualized through various fields of flow quantities.

Influence of Non-Newtonian Rheology on Mass Transfer From a Biofluid in Separated and Reattached Flows

2018 ◽  
Author(s):  
Khaled J. Hammad
Keyword(s):  
Mass Transfer ◽  
Yield Stress ◽  
Mass Transfer Rate ◽  
Flow Region ◽  
Shear Thinning ◽  
Recirculation Region ◽  
Transfer Rates ◽  
Separated And Reattached Flow ◽  
The Impact ◽  
Wall Mass

Influence of the rheological model selection on the flow and mass transfer behavior of human blood in a separated and reattached flow region is investigated. Newtonian and non-Newtonian hemorheological models that account for the yield stress and shear-thinning characteristics of blood are used. The conservation of mass, momentum, and species equations as well as the Herschel-Bulkley constitutive equation are solved numerically using a finite-difference scheme. A parametric study is performed to reveal the impact of flow restriction and rheological modelling on blood-borne oxygen exchange with the confining walls. The wall mass transfer rates within the separated and reattached regions display a strong dependency on the used hemorheological model. Newtonian and non-Newtonian models result in a peak wall mass transfer rate within the recirculation region. However, non-Newtonian models that account for the yield stress and shear-thinning effects predict a substantial, highly localized, drop in the wall mass transfer rates of oxygen, at the reattachment point.

Sign in / Sign up

Export Citation Format

Share Document