Issues whith kEpsilon and porous zones.

lfbarcelo · April 28, 2014, 15:29

Hi all,

I am trying to simulate an air duct with porousSimpleFoam, and in the first steps of the simulation epsilon around the porousZones rises to extremely high values (i.e.: 1E+09).

In some cases the epsilon bounding does its work and the case finally converges, but most times the solution cannot be reached.

This effect has happened repeatedly in different simulations, for different geometries, and I guess it is not a BC issue because the exact thing happens in pressure and velocity driven cases with completely different BCs.

Reynolds for these cases is around 450000. Ducts are rectangular and the mesh is unstructured (tet volumes) but made in a way that faces of the porous zone are completely planar.

OpenFoam version is 2.1.x.

Any comment on this issue will be welcome.
Best Regards.

ngj · April 28, 2014, 17:47

Good evening,

Please be aware that the presence of the porous medium introduce additional terms in the turbulence equation, e.g. k and epsilon. You should verify that these are actually present in the turbulence closure of your choice.

Kind regards,

Niels

April 28, 2014, 15:29	Issues whith kEpsilon and porous zones.	#1
lfbarcelo Member Fran Join Date: Sep 2009 Location: Buenos Aires Posts: 38 Rep Power: 17	Hi all, I am trying to simulate an air duct with porousSimpleFoam, and in the first steps of the simulation epsilon around the porousZones rises to extremely high values (i.e.: 1E+09). In some cases the epsilon bounding does its work and the case finally converges, but most times the solution cannot be reached. This effect has happened repeatedly in different simulations, for different geometries, and I guess it is not a BC issue because the exact thing happens in pressure and velocity driven cases with completely different BCs. Reynolds for these cases is around 450000. Ducts are rectangular and the mesh is unstructured (tet volumes) but made in a way that faces of the porous zone are completely planar. OpenFoam version is 2.1.x. Any comment on this issue will be welcome. Best Regards.

April 28, 2014, 17:47		#2
ngj Senior Member Niels Gjoel Jacobsen Join Date: Mar 2009 Location: Copenhagen, Denmark Posts: 1,903 Rep Power: 37	Good evening, Please be aware that the presence of the porous medium introduce additional terms in the turbulence equation, e.g. k and epsilon. You should verify that these are actually present in the turbulence closure of your choice. Kind regards, Niels __________________ Please note that I do not use the Friend-feature, so do not be offended, if I do not accept a request.