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Ahmed Body Drag coefficient.

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Old   June 22, 2023, 19:04
Default Ahmed Body Drag coefficient.
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Hello everyone

I am currently investigating the effect of slant angle changes on the drag coefficient of an Ahmed Body using Simcenter Star-CCM+.

At this stage I have to validate my sims with the original paper on the Ahmed Body (linked below).
My problem is that my Drag cd values are quite high compared to the experimental value of 0.290 for a slant angle of 25deg according to Ahmedís paper.
I get for k-e 0.377-0.368 and 0.38 for K-omega. I aim to get to 10% error.

I am a CFD beginner and I also somewhat limited by PCís 4 cores, so I only use a model split in half.
One of the problems I have is that parameters such as temp are not stated in the paper, so I assume 1.225 kg/m^3 and 1.79E-5 Pa-s for dynamic viscosity in order to match the paperís Reynoldís number of 4.29 million. I use the same wind tunnel dimensions as Ahmedís paper, using volumetric controls I have made a finer mesh around the AB where most of the interesting features happen with a 4mm custom size.
I have included my sims and some photos of the mesh (using hexahedron mesh).
If you could help me or give me some suggestions I would be very thankful.

Some Salient Features of the Time -Averaged Ground Vehicle Wake
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File Type: jpg mesh-k-omega.jpg (185.5 KB, 7 views)
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ahmed body, drag, drag cd

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