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July 18, 2018, 15:29 |
tangential laplacian, BC
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#1 |
New Member
Artem
Join Date: Apr 2014
Posts: 29
Rep Power: 12 |
Dear all,
I am new with openFOAM and I am trying to implement the following boundary condition at the conducting wall: = a where is electric potential, a is constant, is tangential Laplacian at the wall. I wonder if anybody has an idea about the following question: Is it possible to find tangential Laplacian at the wall in openFOAM and if so - how? I guess that it is only possible to find normal Laplacian, but I will be happy if I am wrong. Thanks in advance. Best regards, Tar Last edited by Kombinator; July 18, 2018 at 18:06. |
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March 5, 2022, 17:21 |
tangential laplacian
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#2 |
New Member
Francesco
Join Date: Jan 2021
Location: UK
Posts: 2
Rep Power: 0 |
Hi,
I know it is an old post but, I am currently working on the same topic. The boundary condition can be created inheriting from fixedGradient. My idea to obtain the tangential components is applying the laplacian to the field, get its value at the boundary and then substract the second derivative of the normal component. One way to obtain the second derivative is: Code:
. . . const volScalarField& PotE = this->db().objectRegistry::lookupObject<volScalarField> ("PotE"); volVectorField gradPotE = fvc::grad(PotE); const vectorField& Sf = patch().Sf(); // surface face vector area const scalarField& magSf = patch().magSf(); // surface area magnitute vectorField normFace = Sf/(magSf+SMALL); // second derivative of normal component scalarField normGradPotE = gradPotE.boundaryField()[patchi].snGrad() & normFace . . . . // update of gradient (lapPotEw is the laplacian at the boundary gradient()= cWall_*(lapPotEw - normGradPotE); I am unfortunately running into divergence problem in my code. By the way, the tangential components of a vector can be extracted as: Code:
n ^ (n ^ v) Hope that this can help! Hopefully somebody else has a better idea |
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July 23, 2024, 11:17 |
tangential BC for laplacian
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#3 |
New Member
Join Date: Mar 2022
Posts: 7
Rep Power: 4 |
Hi,
I am also working on it. Is there any update on it? Wondering if there is not already something available... |
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July 23, 2024, 11:48 |
tangential BC for laplacian
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#4 |
New Member
Francesco
Join Date: Jan 2021
Location: UK
Posts: 2
Rep Power: 0 |
Unfortunately, my approach happened to be unstable. If you are working on thin wall boundary condition for MHD, I think the best approach is solving both solid and fluid, i.e. using a conjugated solver
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