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November 25, 2010, 20:30 |
Hyper viscosity model
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#1 |
Member
Pascal
Join Date: Jun 2009
Location: Montreal
Posts: 65
Rep Power: 17 |
Hi all,
I would like to implement an hyper viscosity model which mean that I need to add the following term in the momentum equation : -nuHV*d⁴U/dx⁴ or nuHV*laplacian(laplacian(U)) where nuHV is the hyper viscosity coefficient. I try this: Code:
volVectorField lap = fvc::laplacian(nuHV/nuHV, U); fvVectorMatrix UEqn ( fvm::ddt(U) + fvm::div(phi, U) - fvm::laplacian(nu, U) + fvm::laplacian(nuHV, lap) ); solve(UEqn == -fvc::grad(p)); Code:
[1] --> FOAM FATAL ERROR: [1] incompatible fields for operation [U] + [((nuHV|nuHV)*laplacian(U))] Then I tried this: Code:
fvVectorMatrix UEqn ( fvm::ddt(U) + fvm::div(phi, U) - fvm::laplacian(nu, U - fvm::laplacian(nuHV/nu, lap)) ); solve(UEqn == -fvc::grad(p)); Thank you, Pascal Last edited by Pascal_doran; November 27, 2010 at 15:45. |
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November 26, 2010, 04:20 |
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#2 |
Senior Member
Christian Lucas
Join Date: Aug 2009
Location: Braunschweig, Germany
Posts: 202
Rep Power: 18 |
Hi,
about the second source code you tried: You want to solve the equation for U (what you do in the first two terms), but in the "new" term, you say that you want to solve the equation for "U-fvm::laplacian(...)". About the first source code you tried: the same error as above, you want to solve the equation for U, not lap. Try to exchange the fvm and fvc for the lap equation and the laplacian term of the first source code Regards, Christian |
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December 1, 2010, 20:51 |
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#3 |
Member
Pascal
Join Date: Jun 2009
Location: Montreal
Posts: 65
Rep Power: 17 |
Thank you Christian,
It works when I tried this: Code:
volVectorField lap = fvc::laplacian(nuHV/nuHV, U); fvVectorMatrix UEqn ( fvm::ddt(U) + fvm::div(phi, U) - fvm::laplacian(nu, U) + fvc::laplacian(nuHV, lap) ); solve(UEqn == -fvc::grad(p)); Code:
volVectorField lap = fvm::laplacian(nuHV/nuHV, U); fvVectorMatrix UEqn ( fvm::ddt(U) + fvm::div(phi, U) - fvm::laplacian(nu, U) + fvm::laplacian(nuHV, lap) ); solve(UEqn == -fvc::grad(p)); Regards, Pascal |
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Tags |
hyper viscosity |
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