[Nek5000-users] Residuals
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
Tue Jun 15 09:46:34 CDT 2010
Hi JC and Paul,
there is a typo -- it should be
n = nx1*ny1*nz1*nelv
Best,
Aleks
On Tue, 15 Jun 2010, nek5000-users at lists.mcs.anl.gov wrote:
>
> PS - I forgot to divide by dt in the routine below.
>
> To do this,
>
>
> dti = 1./dt
> call opcmult(uo,vo,wo,dti)
>
> after opcopy
>
>
> On Tue, 15 Jun 2010, nek5000-users at lists.mcs.anl.gov wrote:
>
>>
>> JC,
>>
>> Given that (v,u_t) = (v,r), where r is the residual, I would
>> assume that you can get the desired residual estimate by looking
>> at u_t := du/dt ~= || u^n - u^n-1 || / dt ?
>>
>> Typically, I would do this in userchk, creating a set of variables
>> in a common block, e.g.
>>
>> parameter (lt=lx1*ly1*lz1*lelt)
>> common /vold/ uo(lt),vo(lt),wo(lt)
>> real linf,l2,h1,semi
>>
>> n = nx1*ny1*nz1*nz1*nelv
>>
>> if (istep.gt.0) then
>> call opsub2 (uo,vo,wo,vx,vy,vz)
>> call normvc (h1,semi,l2,linf,uo,vo,wo)
>> if (nid.eq.0) write(6,1) istep,time,h1,semi,l2,linf
>> 1 format(i8,1p5e13.6,' resnorm')
>> endif
>> call opcopy (uo,vo,wo,vx,vy,vz) ! Save current velocity
>>
>>
>> Then "grep resnorm logfile > t.t" would put the time history
>> of this quantity into the file t.t, assuming your stdout is
>> directed to logfile.
>>
>> Paul
>>
>>
>> On Tue, 15 Jun 2010, nek5000-users at lists.mcs.anl.gov wrote:
>>
>>> Hi Nek's,
>>>
>>> I have a question concerning residuals.
>>> I wanna run a calculation that yields to a stationnary flow. In order to
>>> be sure that my calculation has converged, I'd like to see the residuals.
>>> How/where could I output them ?
>>>
>>> Regards,
>>> JC
>>> _______________________________________________
>>> Nek5000-users mailing list
>>> Nek5000-users at lists.mcs.anl.gov
>>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>>>
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