[Nek5000-users] [*] Re: Postprocessing

[nek5000-users at lists.mcs.anl.gov]

On 03/24/2010 09:58 PM, nek5000-users at lists.mcs.anl.gov wrote:
>
> Mani,
>
> It somewhat depends on what you're after.
>
> You can use postx and compute the vorticity there --- it is
> only 32 bit but it does allow you to compute the vorticity
> for any existing velocity data in the (older) .fld file
> output format.
>
> Alternatively, if you're using VisIt or some other analysis
> tool, or doing run-time analysis, you can compute the vorticity
> at runtime.  If you wish to output the vorticity field, you can
> do so, e.g., as follows:
>
> c-----------------------------------------------------------------------
>       subroutine userchk
>       include 'SIZE'
>       include 'TOTAL'
>
>       parameter(lt=lx1*ly1*lz1*lelv)
>       common /scrns/ vort(lt,3),w1(lt),w2(lt)
>
>       if (mod(istep,iostep).eq.0) then
>          call comp_vort3(vort,w1,w2,vx,vy,vz)
>          call outpost(vort(1,1),vort(1,2),vort(1,3),pr,t,'vrt')
>       endif
>
>       return
>       end
> c-----------------------------------------------------------------------
>
>
> This would generate an output "vrtmy_case..." if your .rea file is
> my_case.rea
>
> Any of the post-processing tools could then read the vrt.... files
> and treat the vorticity as the velocity vector field.
>
> As I say, not exactly sure what you have in mind, but this is one
> possible approach.
>
> Paul
>
>
>
>
>
> On Wed, 24 Mar 2010, nek5000-users at lists.mcs.anl.gov wrote:
>
>> Dear Nek devs,
>>
>>    I'm a bit confused regarding postprocessing. Is one supposed to 
>> run a simulation and then run nek5k again to load the fld files using 
>> load_fld() for postprocessing? Or can one compute the desired 
>> quantities after every time step using userchk() and then output them 
>> in a file? For example, how can I compute the vorticity using the 
>> differential operators defined in the code? After computing the 
>> vorticity, can it be outputted using the same fld files?
>>
>> Regards,
>> Mani chandra
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Dear Paul,

     The files generated by the code in usr_chk(), vrtmy_case0.f* do not 
seem to have vorticity in them when I view them in Visit through the 
database file. They only seem to have pressure, x, y, z components of 
velocity and the velocity magnitude. Could something be wrong?

Mani chandra