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-   -   Is it possible to use divergence in the source term of an scalar transport equation? (http://www.cfd-online.com/Forums/cfx/71601-possible-use-divergence-source-term-scalar-transport-equation.html)

 jannnesss January 8, 2010 20:53

Is it possible to use divergence in the source term of an scalar transport equation?

Hey everyone!!

I have the following problem. I'm trying to implement "Thermophoretic Force/Velocity" in Ansys CFX12. The thermophoretic velocity/force depends on the temperature gradient, which is easy to get in CFX Pre. I want to include the thermophoretic force because of the effect of depostion on particles in aerosol flows.
But the main problem I have is defining the source term of the scalar transport equation of the particles.
The source term should look like this:
div(rho*N_particle*u_th)
The complete Transport Equation should look like this:
d(rho*N_particle)/dt+div(rho*u*N_particle)=-div((rho*N_particle*u_th)
where N is the transported scalar, rho is the density an u_th is the termophoretic velocity vector.
Is there any possibilty to define this source term with CEL or any other method. Is there a possibilty in CFX to calculate the divergence of a Sourceterm?

Or is it possible to define something like a "slip velocity" for a scalar transport equation? The convection term should then look like this:
div(rho*Psi*(U-+U_slip)) where Psi is the general transported scalar

Thanks a lot!!!!!! I tried a lot by using "diffusive transport equations" (the main idea was to hide the thermophoretic velocity in the duffusioncoefficient) but nothing works.
I'm very thankful for every tip!
With best regards,
Jan

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