[Nek5000-users] Explicit Viscosity for Pn-Pn

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

Hi Josh,

Yes nu_star can be set by the user.

A cautionary note --- I've tested this on some semi-analytic
cases and it gives the same results as the Pn-Pn-2 formulation,
which has a well-tested variable viscosity formulation for
the full stress tensor.   Consequently, I was happy with it.

On the other hand, it seems that it does not work as well
as the explicit viscosity formulation set up by Stefan
for the dynamic Smagorinsky model applied to turbulent
flows.  I've not had time to sort this out yet.  Thus,
there'd be some benefit to testing beforehand... I'll be
happy to work with you on this.

Paul


On Fri, 2 Sep 2011, nek5000-users at lists.mcs.anl.gov wrote:

> Howdy Neks,
>
> I had a question about using variable viscosity with the Pn-Pn formulation.
>
> I know I need to have ifuservp and ifexplvis set to TRUE.  Looking
> through the source code, I see that how it works is the viscosity is
> split into an implicit part (nu_star) and explicit.
>
> My question is, how is nu_star set?  Doing a grep on the source code,
> I don't see where it is set anywhere.  So, is this something left up
> to the user?
>
> Thank you,
>
> -- 
> Josh Camp
>
> "All that is necessary for the triumph of evil is that good men do
> nothing" -- Edmund Burke
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