This is a continues note of the cavity tutorial detailed in OpenFoam UserGuide.
Below is the picture giving the comparison of pressure and velocity magnitude predicted in gradedMesh and previous refinedMesh (1600cells case).
Below is the picture giving the comparison of pressure and velocity magnitude predicted in gradedMesh and previous refinedMesh (1600cells case).
Followed by line comparison of axial velocity across two points (0.05, 0, 0.005) and (0.05, 0.1, 0.005).
Slight difference can be observed which is only a problem of numerical errors.
The highest velocity region is expected to have more cells to reduce the error, no confirmed judgement of correctness is given to the prediction at the moment, but the refined one may have presented more accurate result.
Slight difference can be observed which is only a problem of numerical errors.
The highest velocity region is expected to have more cells to reduce the error, no confirmed judgement of correctness is given to the prediction at the moment, but the refined one may have presented more accurate result.
The comparison of two Re of 100 and 10000 is presented below that the former is directly solved, and the latter uses K-epsilon model.
In the latter case, as the viscosity is low, the boundary layer next to the moving lid is very thin and the cells centre next to the lid are comparatively far from the lid so the velocity at their centres are much less than the lid velocity.
->Think about when fluid is air or oil, which one easy drags the fluid right beneath the moving lid? certainly the oil with larger viscosity.
In the latter case, as the viscosity is low, the boundary layer next to the moving lid is very thin and the cells centre next to the lid are comparatively far from the lid so the velocity at their centres are much less than the lid velocity.
->Think about when fluid is air or oil, which one easy drags the fluid right beneath the moving lid? certainly the oil with larger viscosity.
Finally a few commands relevant to Linux case running in the background are given here:
(note in UserGuide, the given command "nohup nice -n 19 icoFoam > log &" will induce errors)
Instead, try to use command like below:
nohup nice -n 19 icoFoam 1>>logs 2>>err &
Where icoFoam is the solver name.
1 represents log data, and 2 represents error data.
nice 19->lowest priority, -20->highest priority. (Range -20 to 19)
More fundamental job control commands in Linux can be found in:
linuxcommand.org/lts0080.php
(note in UserGuide, the given command "nohup nice -n 19 icoFoam > log &" will induce errors)
Instead, try to use command like below:
nohup nice -n 19 icoFoam 1>>logs 2>>err &
Where icoFoam is the solver name.
1 represents log data, and 2 represents error data.
nice 19->lowest priority, -20->highest priority. (Range -20 to 19)
More fundamental job control commands in Linux can be found in:
linuxcommand.org/lts0080.php