[HiroakiSumikawa]

Hi everyone,

I am trying to separate thrust and drag using OpenFOAM. Specifically, I use sampleDict to output grad(U) and pressure on the model surface, then calculate pressure drag and friction drag for each small surface area, considering the positive part as thrust and the negative part as drag.

In the fores.C file, I found the expression `-rho()*nu*dev(twoSymm(fvc::grad(U)))`. When I used this expression, the results of laminar flow analysis matched the drag obtained with the forces function, but the results of the k-omega SST model were about 1/5 smaller.

I have been searching for how the forces function calculates drag for the k-omega SST model but haven't been able to find the details. Does anyone know the exact formula used for drag calculation in the forces function for the k-omega SST model? Any guidance would be greatly appreciated.

Thank you in advance for your help!

Best regards,
Hiroaki Sumikawa