[Nek5000-users] conj. ht. transfer

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

Hmm, that puts some pressure on me. Investigation starts now :)
Cheers,
Stefan

On 10/16/11, nek5000-users at lists.mcs.anl.gov
<nek5000-users at lists.mcs.anl.gov> wrote:
>
> 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.  _______________________________________________
>> Nek5000-users mailing list Nek5000-users at lists.mcs.anl.gov
>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>>
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