[Nek5000-users] Stochastic inflow boundary condition using previous time step velocities?

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

Hi,

I had asked this question yesterday.

How do I call the velocities from the previous time step (time-dt) in
subroutine userbc()?

Thanks,

Harish.


On Thu, July 29, 2010 3:27 pm, nek5000-users at lists.mcs.anl.gov wrote:
> Hello,
>
> I am trying to code a stochastic inlet boundary condition for a backward
> facing step case. I am using the PN/PN-2 formualtion at Re=28,000.
>
> In this b.c., we use previous time step values to initialize the
> fluctuations and final fluctuations are done using the stochastic model.
>
>   ufluct = u(t-dt) - umean
>   ...........
>   ...........
>   ...........
>   ux = uprime + umean
>
> To implement this in subroutine USERBC, I am facing trouble to use the
> previous time step values.
>
> Are they stored in VXLAG(LX1,LY1,LZ1,LELV,1)? How can I call those
> velocities in USERBC? And can I do this?
>
>   ufluct = vxlag(1,1,1,1,1) - umean
>
> Thanks,
>
> Harish.
>
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