How to output porous force in OF221
I am using porousInterFoam and porousWaveFoam in OF221, and want to output the drag force inside the porous media but cannot figure out the method. I define the porous media in blockMeshDict with a block
hex (1 2 6 5 13 14 18 17) porosity (73 93 1) simpleGrading (1 1 1) and in porosityZone file define the property of it Code:
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porousforces Anyone know how to output the porous force in the porous media zone. |
Did you ever find a solution?
I too am looking to work out porousity drag in openfoam and was wondering if you ever found a solution?
It doesn't make sense that a porous region is a cellzone to work out the forces on a patch (unless the zone is 1 cell wide), but even then you can't have the face bounding your porous region be patches else the flow wont go though them... |
Do you have found any solution to the problem?
I have the same request but I don't find a workaround. |
Greetings to all!
I had this thread on my to-do list for a while now and finally managed to look into this. I have to admit I was going to say at first that this wasn't possible, but after some searching and looking into the source code, here's what I've found:
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porosity true; Code:
porousforces Bruno |
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I would like to revive this thread since I have not yet found an answer to the main question in the forum.
I attach a simple case to work with. The domain is a simple box with a porous zone in it and the flow solution seems reasonable. The outputted forces though seems enormously high. This may not be a surprise considering that i specified a cellZone (named framework) instead of a patch in the forces dictionary (see below). Can I tell the functionObject that framework is a porous cellZone and not a patch? Or is there something else that is wrong? Code:
forces_1 |
I seem to have found the reason for the extremely high forces, simply i forgot to scale the mesh before running...
Also, I noticed an error message when running the solver that complained about framework not being a patch. So I tested to remove all entries from the patch list in the dictionary (see below) and the error message disappeared. the porous forces are outputted anyway. I presume this means that the functionObject will print out forces exherted on all porous zones in the domain. Code:
forces_1 |
next question is then: if there are several porous zones in the domain, is there a way to output the forces on a single porous zone rather than the sum of the forces on all zones? any suggestions are appreciated!
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I am using OF 2.3.1. By the way, thank you for your previous post where you discussed the keyword "porosity" |
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edit: Sorry, forgot to mention that the piece of code you're looking for is here: https://github.com/OpenFOAM/OpenFOAM.../forces.C#L923 - starts in line 923, "fPTot" and "Md" is what you're looking for. |
Thanks for the suggestion and the links. I doubt that I will be able to modify the code but I will give it a try later on. If i can get it to work i will post the result.
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Hi All
I have the following question about porosity part of forces How OF calculated the forces applied on the porous zones ? what formula is used for calculating the forces thanks for any help |
@mechy: Quick answer... Given my old answer:
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Dear Bruno
thanks so much for your reply. I have found that the force is calculated by integrating of Darcy-Forchimmer term over the porous volumes. I need to calculate the force on the porous-fluid interface by integrating the pressure and viscous stress on the interface. however, the force library only gives the patches as its input. and this library can not give the interface for calculating the force. I will be so thankful if you can help me to calculate the force on the fluid-porous interface Best Regards |
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