Entropy production in turbulent convection: an analysis based on direct numerical simulation of a plane channel flow

2009 ◽  
Author(s):  
P. Kis ◽  
H. Herwig
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Entropy Production ◽  
Channel Flow ◽  
Plane Channel ◽  
Turbulent Convection ◽  
Plane Channel Flow

scholarly journals Flow Statistics in the Transitional Regime of Plane Channel Flow

Entropy ◽  
2020 ◽  
Vol 22 (9) ◽  
pp. 1001 ◽  
Author(s):  
Pavan Kashyap ◽  
Yohann Duguet ◽  
Olivier Dauchot
Keyword(s):  
Numerical Simulation ◽  
Channel Flow ◽  
Plane Channel ◽  
Turbulent Regime ◽  
Transitional Regime ◽  
Strong Linear Correlation ◽  
Transitional Point ◽  
Spatio Temporal ◽  
High Order Statistics ◽  
Plane Channel Flow

The transitional regime of plane channel flow is investigated above the transitional point below which turbulence is not sustained, using direct numerical simulation in large domains. Statistics of laminar-turbulent spatio-temporal intermittency are reported. The geometry of the pattern is first characterized, including statistics for the angles of the laminar-turbulent stripes observed in this regime, with a comparison to experiments. High-order statistics of the local and instantaneous bulk velocity, wall shear stress and turbulent kinetic energy are then provided. The distributions of the two former quantities have non-trivial shapes, characterized by a large kurtosis and/or skewness. Interestingly, we observe a strong linear correlation between their kurtosis and their skewness squared, which is usually reported at much higher Reynolds number in the fully turbulent regime.

scholarly journals Artificial boundary conditions for the ILES modeling of plane channel flow using the Cabaret scheme

2019 ◽  
pp. 12-20
Author(s):  
Д.Г. Асфандияров
Keyword(s):  
Numerical Simulation ◽  
Boundary Conditions ◽  
Channel Flow ◽  
Plane Channel ◽  
Pseudospectral Method ◽  
Artificial Boundary ◽  
Cabaret Scheme ◽  
Artificial Boundary Conditions ◽  
Wide Range ◽  
Plane Channel Flow

Представлены результаты ILES-моделирования классической задачи течения вязкой несжимаемой жидкости в плоском канале по схеме Кабаре. Рассматривается возможность модификации расчета течения возле стенки для более точного определения средних характеристик. Предложено введение "искусственных" граничных условий путем использования в первом слое ячеек вблизи стенки специальной модели вихревой вязкости для корректного учета сдвиговых эффектов. Приводится сравнение результатов расчета течения в плоском канале по схеме Кабаре с предложенными искусственными граничными условиями и без в широком диапазоне чисел Рейнольдса. Показано, что введенные модификации в пристеночном слое позволяют повысить точность определения средних характеристик течения, в особенности вторых моментов. Полученные данные также сравниваются с результатами LES-моделирования с использованием псевдоспектрального метода и с данными прямого численного моделирования. Some results of ILES modeling of the plane channel flow of a viscous incompressible fluid using the Cabaret scheme are discussed. The possibility of modifying the calculation of flow near the wall is considered to determine the average characteristics more accurately. The "artificial" boundary conditions are introduced by using a special eddy viscosity model in the first layer of cells near the wall to correctly account for shear effects. The results of numerical simulation of plane channel flow obtained using the Cabaret scheme with and without artificial boundary conditions are compared in a wide range of Reynolds numbers. It is shown that the introduced modifications in the near-wall layer improve the accuracy of determining the average flow characteristics, especially the second moments. The obtained data are also compared with the results of LES modeling by the pseudospectral method and with the data from direct numerical simulation.

Simulation of Flows in Plane Channel With a Hemisphere at the Bed by DNS and Immersed Boundary Method

2004 ◽  
Author(s):  
Thein Xuan Dinh ◽  
Y. Ogami
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Channel Flow ◽  
Immersed Boundary Method ◽  
Plane Channel ◽  
Turbulent Channel Flow ◽  
Immersed Boundary ◽  
Boundary Method ◽  
History Of ◽  
Drag And Lift

In order to develop an immersed boundary method for direct numerical simulation of turbulent and complicated boundary flow, we perform the method proposed by Kajishima for a fully developed turbulent channel flow with a hemisphere at the bed. The correlation between drag and lift, history of rollup moments about the specified contact axis and the distribution of pressure over the hemisphere in the plane of symmetry are presented. We also focus on instants of high rollup moment structure of the flow.

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