simpleFoam

onurcanpiskin · March 13, 2024, 05:56

Hello, I am performing aerodynamic analysis for external flow. I get results that are far from the drag values I need. I use the K-W SST model. Since I work at 100m/s, my kinetic energy and omega values are very high. I think there is no error in my case file, but my results are very high. Can you help me with this?

Severus · March 13, 2024, 13:05

Hello,
Check out these recent threads
Unable to validate Drag coefficient for Flow past a sphere using OpenFOAM
Drag coefficient of sphere & spherical bubble at Re = 1

For drag the most common reason is the mesh refinement near the wall in order to capture the boundary layer accurately.
It should be well refined. Since you use RANS turbulence modelling, the mesh spacing at the walls should be related to the y+ values.
If you use wall functions, y+ should be between 30 and 100. If you don’t use wall functions (low Re turbulence models), y+ should be less than 5.

A suggestion: Please name your thread better (relevant name) next time so that people in future can find it easily

Thanks

March 13, 2024, 05:56	simpleFoam	#1
onurcanpiskin New Member onurlands Join Date: Feb 2024 Posts: 25 Rep Power: 2	Hello, I am performing aerodynamic analysis for external flow. I get results that are far from the drag values I need. I use the K-W SST model. Since I work at 100m/s, my kinetic energy and omega values are very high. I think there is no error in my case file, but my results are very high. Can you help me with this?

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March 13, 2024, 13:05		#2
Severus Member Shravan Join Date: Mar 2017 Posts: 60 Rep Power: 9	Hello, Check out these recent threads Unable to validate Drag coefficient for Flow past a sphere using OpenFOAM Drag coefficient of sphere & spherical bubble at Re = 1 For drag the most common reason is the mesh refinement near the wall in order to capture the boundary layer accurately. It should be well refined. Since you use RANS turbulence modelling, the mesh spacing at the walls should be related to the y+ values. If you use wall functions, y+ should be between 30 and 100. If you don’t use wall functions (low Re turbulence models), y+ should be less than 5. A suggestion: Please name your thread better (relevant name) next time so that people in future can find it easily Thanks