[Nek5000-users] Residuals
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
Tue Jun 15 09:44:39 CDT 2010
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
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