[Nek5000-users] conj. ht. transfer

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

Dear Andrea,

Thank you for your careful investigation of this issue.
We'll dig into it in the next 36 hours and hopefully we
will get the problem resolved quickly.

Best regards,

Paul




On Sun, 16 Oct 2011, nek5000-users at lists.mcs.anl.gov wrote:

> Dear all,
>
> I was running a simple case with conjugate heat transfer. I managed to
> validate it against some analytic data.  I checked whether the heat fluxes at
> the interface between solid and fluid match or not. For any ratio of solid
> conductivity over fluid conductivity they match very well especially if the
> grid is very refined at the interface. The problem is that they match only if
> vtrans of solid is the same as vtrans of the fluid, else the ratio of the two
> fluxes is proportional to the ratio of vtrans, which is wrong.  I had a look
> into the code even though I am not very expert. I am using cvode. In fcvfun
> there is a call to makeq. In makeq, after the call to wlaplacian and add2,
> the rhs, which is bq, is divided by vtrans. When we are back to fcvfun, there
> is a call to dssum over ydot. I am not sure but I think that dssum mixes the
> properties of fluid and solid, therefore the transient equation which is
> solved for the temperature at the interface has a flux which is divided by
> vtrans of the fluid and another flux which is divided by vtrans of the solid,
> therefore the two fluxes can not match at the interface unless solid and
> fluid have the same vtrans.  If this is really the problem, I think it could
> be solved by dividing bq at the interface by vtrans of the solid only, before
> dssum is performed.  I'll check again my case to be sure that what I observed
> was not due to an error.
>
> Thanks in advance for your help.
>
> Regards, Andrea.  _______________________________________________
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>