|
[Sponsors] |
June 21, 2016, 03:41 |
precision difference OF-2.3.0 and OF-2.3.1
|
#1 |
New Member
Matthias Stammen
Join Date: Oct 2010
Posts: 8
Rep Power: 15 |
Hello,
for some special analysis I need a very high numerical precision of of the flow field (so, double precision everywhere). And accidentally, I came along a small difference between the versions OF-2.3.0 and OF-2.3.1. Running the same code in the same case, I get max. velocities which differ after 6 digits. Some example results: code compiled with OF-2.3.0I compiled the two different OF-versions on the same machine, using the same compiler, but I always get these small differences (in serial and parallel). I searched in the src folder (using meld), but didn't find the files which could explain this difference. Does anyone has an idea? Thanks, Matze PS: It is a simple 2D airfoil using the SIMPLE algorithm and inletOutlet BCs on a circular domain. writePrecision is set to 15. |
|
June 22, 2016, 07:41 |
|
#2 |
New Member
Matthias Stammen
Join Date: Oct 2010
Posts: 8
Rep Power: 15 |
After running several more simulations and checking the codes again, I found that the relevant difference is the delta() function in
src/finiteVolume/fvMesh/fvPatches/fvPatch/fvPatch.C OF-2.3.0: OF-2.3.1:So, the difference is that in OF-2.3.1 only the normal part of the cell-centre to face-centre vector is used. As far as I know, this delta is used for the computation of the Laplacian term, but I'm still not sure which one is correct and why this change was done... Any ideas? |
|
|
|