|June 7, 2014, 05:40||
LES pipeflow dynOneEddy strange results
Join Date: Feb 2014
Location: Darmstadt, Germany
Posts: 88Rep Power: 5
I've done some LES simulations of pipeflow with dynOneEddy-Model and compare my results with oneEddy-Model and WALE model. I get some strange results for ksgs -> nuSgs.
first some informations:
1) problem description
- pipe diameter 0.04m
- length of the pipe 4*D (cyclic Boundary conditions)
- fluid water nu=1.081e-06
- incompressible flow Re=4900, Retau=340
- Grid: structured O-Grid
r+ wall = 2,5
r+ mean = 7.5
z+ = 35
eta+ = 10
I have also used finer grid and I have the same problem (problem see below)
2) Boundary conditions:
---k , p , nuSgs---
value uniform (0 0 0);
- I used pressureGradientExplicitSource to get the cyclic flow.
- all schemes Gauss linear or Gauss linear corrected
- ddtSchemes: backward
- pimple with residual control U,p<10^-5, k<10^-7
- initalize the U-field fully turbulent by mapping data from other simulation
- fieldAverage 200D
The velocity profiles in u+ y+ looks ok for all models (dynOneEddy is ok but the others are better). But in dynOneEddy-model I get strange behavour for nuSgsmean and kSgsmean.
--------- Here my results for nuSgsmean over 200D----------
looks good. At the wall, nuSgs decrease because of WALE model. NuSgs is smooth ober the domain
results looks reasonable, because I do not use van Driest damping at the wall and it is not a dynamic procedure implemented. But nuSgs is smooth.
looks not good!! Why these two stripes???
------ Here my results for kSgsmean-------------
looks reasonable, because no dynamic procedure implemented.
puuh, What's going on at the wall?? What about these two stripes again??
In dynOneEddy-model the results for nuSgsmean and kSgsmean looks strange. First I thought it is the grid. But even with finer grid I get the same results. For Smagorinsky, dynamicSmagorinsky, WALE, OneEddy-model I get with this mesh, bc etc. good results. Whats wrong with dynOneEddy-model???
Is there a fault in the implementation of the dynamic procedure in dynOneEddy-model??
Somebody an idea???
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