Laplacian of a TensorField ?
 

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??

so what you are saying is
I hope you see the mistake here

Hi
 

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

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.

HI
 

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

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.

Thanks
 

Thanks a lot Niklas