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September 23, 2010, 08:11 |
Laplacian of a TensorField ?
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#1 |
Senior Member
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Hi,
How to calculate laplacian of A*T if A is a scalar function of another scalar Main field c and , T is a 2nd order tensor example when i put " solve ( fvm::ddt(c) + fvm::div(phi,c) == fvm::laplacian(A,T) ); A=2*pow(c,2)+5; " it doesnot work!!!!? Help lease?? |
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September 23, 2010, 08:18 |
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#2 |
Super Moderator
Niklas Nordin
Join Date: Mar 2009
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September 23, 2010, 09:02 |
Hi
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#3 |
Senior Member
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Execuse me,
In another words the last term to the write is ∇·(A*(∇.T)) which must be a scalar ok to go on with the c equation. where A is a scalar and T is a second order tensor so ∇·T is div(T) and it is a vector ok (since divergence of a tensor) ?? and V=A*∇·T is a vector then so ∇·(A*(∇.T)) must be written something like div(A,V) ?? knowing that A is always a function of c. helpme Thanks |
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September 23, 2010, 09:14 |
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#4 |
Super Moderator
Niklas Nordin
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ah ok, so its 2 div operations...
∇·(A*(∇.T)) = fvc::div(A*fvc::div(T)) but this will make this term fully explicit. I think it will be hard to treat it fully implicit. If you run into stability problems you should try to split it up into implicit/explicit parts. |
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September 23, 2010, 10:43 |
HI
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#5 |
Senior Member
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Hi Niklas thanks,
BUT A is a function of the scalar field c. so it stays like that ∇·(A*(∇.T)) = fvc::div(A*fvc::div(T)) ?? another thing please: do you know how to turn off all dimensions? thank you so much |
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September 23, 2010, 10:54 |
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#6 |
Super Moderator
Niklas Nordin
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yes of course it does.
and why do you want to turn off dimensions, it has saved me on numerous occasions. but ok, I can see that the exp-function can give you problems. if you are using 1.7.1 it is in OpenFoam-1.7.1/etc/controlDict lookup the line dimensionSet 1; and change the 1 to 0. |
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September 23, 2010, 13:40 |
Thanks
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#7 |
Senior Member
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Thanks a lot Niklas
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