[Nek5000-users] Outflow divergence

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

I also had problems using the Outflow divergence b.c. with PN/PN formulation.
Paul suggested that I switch ot PN/PN-2 formulation and that worked fine for
me.

Thanks Stefan, it would be great if this b.c. can be made to work with
SPLIT formulation, because my labmate will need it for low Mach number
simulations.

Harish.

On Mon, 26 Jul 2010 nek5000-users at lists.mcs.anl.gov wrote:

> I will take care of this.
> Let you know when it's fixed.
>
> Stefan
>
>
> -----Original Message-----
> From: nek5000-users-bounces at lists.mcs.anl.gov on behalf of nek5000-users at lists.mcs.anl.gov
> Sent: Mon 7/26/2010 05:36
> To: nek5000-users at lists.mcs.anl.gov
> Subject: Re: [Nek5000-users] Outflow divergence
>
>
> Hi Markus,
>
> This question came up earlier for the splitting code...
> I apologize that I don't recall the precise resolution
> but it's clear that there is a problem for the splitting
> case.
>
> I'll try to recall precisely how we fixed it for that
> particular case.
>
> Paul
>
>
> On Sun, 25 Jul 2010, nek5000-users at lists.mcs.anl.gov wrote:
>
> > Howdy neks,
> >
> > I updated my divergence-for-outflow code from the latest repo of the jet
> > example case (since I have a suspicion the old one is messing with my
> > simulation upstream of the outflow) and found the following issue:
> > "
> >      if (ifsplit) then
> >         do i=1,ntot2
> >            dd = dist(i,1,1,1)*dist(i,1,1,1)
> >            dd = min(dmax2,dd)
> >            if (dist(i,1,1,1).ge.0) usrdiv(i,1,1,1) = cdiv*(1.-dd/dmax2)
> >            if (dist(i,1,1,1).ge.0) nd = nd+1
> >         enddo
> > "
> > This seems to add user divergence linearly in the outflow elements (from zero
> > at the farthest distance from the outfow face to some value at it), which is
> > intended, but also adds divergence everywhere else (dd&dist are zero in all
> > non-outflow elements). This of course causes undesired acceleration in domain
> > parts where I'd like to keep a constant flow rate, say.
> >
> > Was the intention: "if (dist(i,1,1,1).gt.0) usrdiv(i,1,1,1) =
> > cdiv*(1.-dd/dmax2)"?
> > How is "ifsplit true" treated differently from "false" in this regard?
> >
> > Thanks,
> > Markus
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