No outlet flow in porousSimpleFoam

Outbound · July 20, 2016, 10:08

Hi,

I'm having trouble simulating an open channel flow (with wall with slip condition standing for free surface) with porous medium in porousSimpleFoam because for some reason I get no outlet flow out of the outlet patch.

For some reason there is volumetric flow into the control volume but I don't understand with the outlet patch doesn't output any of the flow.

I've set up the case like so to try out the conditions as I was already having this problem with the actual compound channel flow mesh.

The porosity cellset indefined in blockMeshDict. What I'm not sure on is why no flow out of the CV through the outlet patch. I even tried adding a porosity free buffer zone after the porous cellset but after a few seconds it still seems like the boundary conditions are ill-defined.

I was able to run simple flow in a square channel in simpleFoam. Is it possible to add porosity to that simulation?

Thank you for any help you might provide.

Outbound · July 21, 2016, 13:16

I should note that I switched the turbulence model from kEpsilon to kOmegaSST.

Is it possible that I've ill-defined the parameters for the boundary conditions for this model and that that's what's causing the blockage at the outlet patch?

Outbound · August 9, 2016, 12:06

FYI, there seems to be a problem with porousSimpleFoam with porous cellsets parallel in flow direction to freeflow cellsets. The solver seems to take into account an extra patch which becomes undefined and which essentially blocks the flow.

It doesn't seem to be a problem in simpleFoam since the exact same mesh with the exact same boundary conditions seem to work fine in simpleFoam, with the porosity properties being defined in the fvOptions file.

Outbound · August 11, 2016, 06:51

Ah, I've run into the same problem in simpleFOAM.

The fault seems to be that I'm not applying the kOmegaSST turbulence model correctly.

The flow seems to work fine with the realizableKEpsilon model, but as soon as I switch to kOmegaSST I get the same problem of the flow being impeded at the outlet.

July 20, 2016, 10:08	No outlet flow in porousSimpleFoam	#1
Outbound Member António Soares Join Date: Mar 2015 Location: Lisbon, Portugal Posts: 48 Rep Power: 11	Hi, I'm having trouble simulating an open channel flow (with wall with slip condition standing for free surface) with porous medium in porousSimpleFoam because for some reason I get no outlet flow out of the outlet patch. For some reason there is volumetric flow into the control volume but I don't understand with the outlet patch doesn't output any of the flow. I've set up the case like so to try out the conditions as I was already having this problem with the actual compound channel flow mesh. The porosity cellset indefined in blockMeshDict. What I'm not sure on is why no flow out of the CV through the outlet patch. I even tried adding a porosity free buffer zone after the porous cellset but after a few seconds it still seems like the boundary conditions are ill-defined. I was able to run simple flow in a square channel in simpleFoam. Is it possible to add porosity to that simulation? Thank you for any help you might provide.

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July 21, 2016, 13:16		#2
Outbound Member António Soares Join Date: Mar 2015 Location: Lisbon, Portugal Posts: 48 Rep Power: 11	I should note that I switched the turbulence model from kEpsilon to kOmegaSST. Is it possible that I've ill-defined the parameters for the boundary conditions for this model and that that's what's causing the blockage at the outlet patch?

August 9, 2016, 12:06		#3
Outbound Member António Soares Join Date: Mar 2015 Location: Lisbon, Portugal Posts: 48 Rep Power: 11	FYI, there seems to be a problem with porousSimpleFoam with porous cellsets parallel in flow direction to freeflow cellsets. The solver seems to take into account an extra patch which becomes undefined and which essentially blocks the flow. It doesn't seem to be a problem in simpleFoam since the exact same mesh with the exact same boundary conditions seem to work fine in simpleFoam, with the porosity properties being defined in the fvOptions file.

August 11, 2016, 06:51		#4
Outbound Member António Soares Join Date: Mar 2015 Location: Lisbon, Portugal Posts: 48 Rep Power: 11	Ah, I've run into the same problem in simpleFOAM. The fault seems to be that I'm not applying the kOmegaSST turbulence model correctly. The flow seems to work fine with the realizableKEpsilon model, but as soon as I switch to kOmegaSST I get the same problem of the flow being impeded at the outlet.