Hi all I am wondering how I
 

Hi all
I am wondering how I can insert the diffusion term in the convervative form of NS equations (i.e. rhoU, rhoE) in compressible solvers (like rhoSonicFoam).
If I use a term like

fvc:laplancian(mu, U)+1/3*div()

such an explicit treatment would require very small timesteps.
Another possibility is to express the diffusions in terms of rhoU, but in this case a huge number of additional terms appear (both implicit and explicit).
I am sure there is a very simple way to do this with OpenFoam, but the documentation is huge and a starting tip would be great http://www.cfd-online.com/OpenFOAM_D...ipart/wink.gif
Thanks
Massimiliano