Large Eddy Simulation of Constant Heat Flux Turbulent Channel Flow With Property Variations: Quasi-Developed Model and Mean Flow Results

2003 ◽  
Vol 125 (1) ◽  
pp. 27-38 ◽  
Author(s):  
Lyle D. Dailey ◽  
Ning Meng ◽  
Richard H. Pletcher
Keyword(s):  
Large Eddy Simulation ◽  
Channel Flow ◽  
Scale Model ◽  
Bulk Temperature ◽  
Finite Volume Scheme ◽  
Subgrid Scale ◽  
Mean Flow ◽  
Eddy Simulation ◽  
Heating And Cooling ◽  
Large Eddy

Turbulent planar channel flow has been computed for uniform wall heating and cooling fluxes strong enough to cause significant property variations using large eddy simulation. Channels with both walls either heated or cooled were considered, with wall-to-bulk temperature ratios as high as 1.5 for the heated case, and as low as 0.56 for the cooled case. An implicit, second order accurate finite volume scheme was used to solve the time dependent filtered set of equations to determine the large eddy motion, while a dynamic subgrid-scale model was used to account for the subgrid scale effects. Step-periodicity was used based on a quasi-developed assumption. The effects of strong heating and cooling on the flow were investigated and compared with the results obtained under low heating conditions.

Large Eddy Simulation of Rotating Channel Flows With and Without Heat Transfer

2000 ◽  
Author(s):  
Ning Meng ◽  
Richard H. Pletcher
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Channel Flow ◽  
Scale Effects ◽  
Scale Model ◽  
Finite Volume Scheme ◽  
Subgrid Scale ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Rotating Channel

Abstract Large eddy simulation of rotating channel flow with and without heat transfer is reported. The rotation axis is parallel to the spanwise direction of the parallel plate channel. An implicit finite-volume scheme was used to solve the preconditioned time-dependent filtered Navier-Stokes equations using a dynamic subgrid-scale model to account for the subgrid-scale effects. Comparisons are made with available results in the literature for isothermal rotating flows. The combined effects of rotation and heat transfer on the structure of turbulence channel flow is discussed.

Study of flow in a planar asymmetric diffuser using large-eddy simulation

1999 ◽  
Vol 390 ◽  
pp. 151-185 ◽  
Author(s):  
H.-J. KALTENBACH ◽  
M. FATICA ◽  
R. MITTAL ◽  
T. S. LUND ◽  
P. MOIN
Keyword(s):  
Kinetic Energy ◽  
Large Eddy Simulation ◽  
Scale Model ◽  
Subgrid Scale ◽  
Mean Flow ◽  
Eddy Simulation ◽  
Unsteady Separation ◽  
Large Eddy ◽  
Rear Part ◽  
Subgrid Scale Model

Large-eddy simulation (LES) has been used to study the flow in a planar asymmetric diffuser. The wide range of spatial and temporal scales, the presence of an adverse pressure gradient, and the formation of an unsteady separation bubble in the rear part of the diffuser make this flow a challenging test case for assessing the predictive capability of LES. Simulation results for mean flow, pressure recovery and skin friction are in excellent agreement with data from two recent experiments. The inflow consists of a fully developed turbulent channel flow at a Reynolds number based on shear velocity, Reτ=500. It is found that accurate representation of the in flow velocity field is critical for accurate prediction of the flow in the diffuser. Although the simulation in the diffuser is well resolved, the subgrid-scale model plays a significant role for both mean momentum and turbulent kinetic energy balances. Subgrid-scale stresses contribute a maximum of 8% to the local value of the total shear stress with the maximum values found in the inlet duct and along the flat wall where the flow remains attached. The subgrid-scale model adapts to the enhanced turbulence levels in the rear part of the diffuser by providing more than 80% of the dissipation rate for turbulent kinetic energy. The unsteady separation excites large scales of motion which extend over the major part of the duct cross-section and penetrate deeply into the core of the flow. Instantaneous flow reversal is observed along both walls immediately behind the diffuser throat which is far upstream of the location of main separation. While the mean flow profile changes gradually as the flow enters the expansion, turbulent stresses undergo rapid changes over a short streamwise distance along the deflected wall. An explanation is offered which considers the strain field as well as the influence of geometry changes. The effect of grid resolution and spanwise domain size on the flow field prediction has been documented and this allows an assessment of the computational requirements for carrying out such simulations.

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