[Nek5000-users] Linearised Navier-Stokes time-dependant base flow

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

Dear JP,

In perturb.f, the driver reads:

       do jp=1,npert

          if (nid.eq.0.and.igeom.eq.2) write(6,1) istep,time,jp
    1     format(i9,1pe14.7,' Perturbation Solve:',i5)

          call perturbv (igeom)

       enddo

       jp=0   ! set jp to zero, for baseline flow


So, the appropriate discriminator in userbc would be:

       if (jp.eq.0) then

          ux=1

       else

          ux=0

       end

Best regards,

Paul




On Thu, 30 Jan 2014, nek5000-users at lists.mcs.anl.gov wrote:

> Hi Nek's,
>
> I have a question regarding the linearised Navier-Stokes solver while the
> underlying base flow is time-dependant. As far as I understand, one should
> simply have to set param(31) = 1 to achieve this (and p31 = -1 for a steady
> state base flow). What about the boundary conditions however?
>
> For instant, I want to investigate the linear dynamics of perturbations
> evolving onto a lid-driven cavity flow exhibiting a periodic limit cycle I
> have computed. How could I impose in userbc:
>
> ux = 1
> uy = 0
> uz = 0
>
> for the periodic base flow time-evolution, and in the meantime:
>
> ux = 0
> uy = 0
> uz = 0
>
> for the perturbation?
>
> Cheers,
> JC
>
> -- 
> Jean-Christophe Loiseau
> Homepage <https://sites.google.com/site/loiseaujc/>
>