# velocity divergence as plot

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 October 12, 2001, 03:28 velocity divergence as plot #1 Sabatini Guest   Posts: n/a Hallo people Is there a way to extract the velocity divergence as plot Thanks

 October 16, 2001, 05:56 Re: velocity divergence as plot #2 Paal Guest   Posts: n/a Hi, I am not fully sure that I get your question right: Do you want to plot the diverged "results"? These results are saved to a file - case.div, and can be loaded in the same manner as normal result files just replacing the case.pst with case.div

 October 16, 2001, 12:11 Re: velocity divergence as plot #3 steve Guest   Posts: n/a I think to get what you want you have to load velocities (GETV,ALL) and then use OPERATE,CURL function. I think CURL is the same as divergence of a function?

 October 17, 2001, 01:49 Re: velocity divergence as plot #4 Lars Ola Liavåg Guest   Posts: n/a The curl of a vector field is itself a vector (cross product of the "upside down" delta and the vector), whereas the divergence (the corresponding dot product) is a scalar. Hence, for the velocity vector V, div V = du/dx + dv/dy + dw/dz, whereas curl V = i(dw/dy - du/dz) + j(du/dz - dw/dx) + k(dv/dx - du/dy), all d's being partial differentials. In PROSTAR, the OPERATE,CURL function takes the curl of the loaded vector field and returns the curl (vector) of it. You can also calculate the gradient vector, but I don't know how to calculate the divergence in PROSTAR. I guess contacting the support team is a good idea.

 January 21, 2002, 09:30 Re: velocity divergence as plot #5 daniel Guest   Posts: n/a CURL is definitely NOT the same as the divergence of a function, but a DIV command should also be available the same way

 January 28, 2002, 19:07 Re: velocity divergence as plot #6 cfd Guest   Posts: n/a Continuity equation: div(rho u) = d(rho)/dt For a converged steady state solution: div(u) -> 0. For a transient compressible time step solution: div(u) = 1/rho [d(rho)/dt - u grad(rho)] For incompressible time step solution: (rho = const.): div(u) -> 0.