2nd derivative in UDS -- CFD Online Discussion Forums

January 19, 2005, 11:35	2nd derivative in UDS	#1
Andrew Garrard Guest Posts: n/a	Please Please Help someone. I am trying to model a diffuion - convection - migration problem with a UDS. The transport equation I want to model is this: del(vel * C) + del( D * del[C]) + del(D * C * A * del[thi]) = 0 Where del is the gradient (sometimes called nabla), vel is the velocity vector, C is the concentration, D is the diffusion coefficient, A is a constant and thi is another UDS (say UDS1). I can write a diffusion/convection UDF easily using the F_FLUX macro, but I have no idea where to start with the last term for migration. Please Please someone help me.

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