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Old   October 12, 2001, 04:28
Default velocity divergence as plot
  #1
Sabatini
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Hallo people Is there a way to extract the velocity divergence as plot Thanks
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Old   October 16, 2001, 06:56
Default Re: velocity divergence as plot
  #2
Paal
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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

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Old   October 16, 2001, 13:11
Default Re: velocity divergence as plot
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steve
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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?
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Old   October 17, 2001, 02:49
Default Re: velocity divergence as plot
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Lars Ola Liavåg
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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.

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Old   January 21, 2002, 10:30
Default Re: velocity divergence as plot
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daniel
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CURL is definitely NOT the same as the divergence of a function, but a DIV command should also be available the same way
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Old   January 28, 2002, 20:07
Default Re: velocity divergence as plot
  #6
cfd
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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.
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