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June 9, 2005, 14:14 |
Time Step for DES
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#1 |
Guest
Posts: n/a
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Hi all
I am using the Detached Eddy Simulation model for predicting the three-dimensional flow field of a round jet in crossflow. The velocity range is from 15-20 m/s and the domain dimensions are 0.75x0.3x0.3 m. I am using a relatively coarse grid of about 90000 nodes, because the simulation is done on a PC. The unsteady parameters that I have used are: Time Step Size: 0.0001 No. of Time Steps: 1000 No. of Iterations per Time Step: 20 I have compared the mean results of the DES and results from steady RANS based simulation using standard k-epsilon model against experimental data, and I found that the steady k-epsilon simulation results are slightly in better agreement with the measurements; however both methods highly over-predicted the velocity profiles (with an error of about 250% for the wall-normal velocity). I just have tow questions: 1. Can I get better results using the same grid size? In other words: Is this grid size appropriate for my problem. 2. What are the appropriate "Time Step Size" and "No. of Iterations per Time Step" that I should use? Thanks a lot. Maged |
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