Coupling with SYRTHES

[Brennan Sharp]

Hello,

I am trying to apply Code_Saturne, coupled with SYRTHES to a forced-air cooling problem. The simulation runs, and coupling appears to be working, however the results I have obtained are noticeably different to what has been measured.

The solid domain is an extruded aluminium heatsink, which has a comb-like cross-section. Heat flux is applied to a small area on the base of the heatsink. Air is blown through a rectangular duct, along the fins of the heatsink.

The measured surface temperatures on the base of the heatsink, which is entirely in the SYRTHES domain, is significantly higher than the simulation results predict.

The coupled faces for the fluid and solid domains are both in their respective 'interace' group. 

I am using a single coupling in ussyrc.f90, which I understand (perhaps wrongly) to be sufficient for coupling one face group in Code_Saturne to one face group in SYRTHES.

Other simulation experiments so far indicate that the problem is not due to mesh or turbulence.

I would appreciate any assistance. I can provide files if necessary.

Regards,

Brennan

[Brennan Sharp]

I've attached a picture showing the geometry. The underside of the heatsink (not visible) has the heat source applied. The fluid is visible as a semi-transparent object attached to the heatsink.

The complete geometry includes inlet and outlet ducts, but not shown here.

[Yvan Fournier]

Hello Brennan,

Using a single coupling in ussyrc.f90 is indeed sufficient. You may also want to activate "ichrsy" in usini1.f90 to obtain a post-processing output of the wall temeperature and heat flux along the selected faces. Along with the histograms in the SYRTHES log, this helps troubleshouting, for example when meshes are in mismatched reference frames and faces are not coupled as expected (in the future, we will add post-processing of the ditance between meshes to better check matching).

Apparently, you've done tests on turbulence, so it seems that the turbulent heat exchange coefficient being too low or too high due to limitations of the turbulecn model and wall law is not the cause of the problem, but it may still be interesting to test the sensitivity of the calculation to the wall function type (in turbulence advanced parameters).

Did you also run tests using SYRTHES only (with an exchange coefficient) to make sure that physical properties in the solid are defined correctly ?

If your files are not too large, you may post them here (preferred), or send them to our saturne-support at edf.fr adress if confidentiality is important.

Regards,

  Yvan

[Brennan Sharp]

Hello Yvan,

Thanks for your answers and advice. I'm confident that the physical properties of the solid (and fluid) are correct.

The possibility of incorrect solid-fluid face has been considered and I experimented with  simpler geometry on the effect of conformal meshes at the interface.

The files are not confidential, in fact my employer has encouraged me to present a Salome+Code_Saturne+SYRTHES tutorial here, but such a tutorial is worthless until  the simulated results results match the measured results.  I'm sure they can, with some help.

The files are a bit big to attach here or to send by e-mail , so I have made them accessible to you via ftp (details sent by e-mail)

I ran a simulation with ICHRSY=1 set as you advised. If I correctly understand the purpose of that, then there did not appear to be any difference in temperature between the SYRTHES interface face and the fluid interface face. However, I did notice some unexpected 'bubbles' of higher temperature in cut-planes of the fluid. The odd thing is that the bubble shapes are not consistent with the mesh.

Regards.

Brennan

[Alicia Consigny]

Hi Brennan,

I'm starting to study the possibilities of coupling between Saturne and Syrthes, and I'm looking for some kind of basic tutorial, from the meshing part to the post processing.

How is your work on the subject progressing ? I see this post is a few month old, so I'm hoping that you managed to obtain good results, in agreement with your measured results. If so, could you please give me some information about your calculation (numerical and physical parameters, ...), maybe even mesh and results files (if they're not confidential) ?

Thanks in advance,

Alicia

[Brennan Sharp]

Hello Alicia,

Sorry for the very late response. I've not been visiting these pages for a long time, until just recently and only noticed your request while searching for something.

If your request still stands, I'd be happy to provide an example coupled study, though maybe by now you can answer my next question!

Regards,

Brennan

[Christoph Neumaier]

Hello Brennan,

I am a PhD student and I am trying to simulate heating mechanisms in high-power coaxial transmissionlines. I would be pleased, if you could send me something to start with/the ftp-address for the download.

Best regards,

Christoph

[Alexandre Douce]

Christopher, this link may be can help :

http://code-saturne.org/forum/viewtopic ... =863#p4831

Brennan, other attached examples are welcome

[Brennan Sharp]

Christopher, Alexandre,

I'm making up a slightly simplified version of one or more coupled cases. The simplification is just to make the file sizes smaller, but the set-up of Code_Saturne and SYRTHES will be the same.

Some of the files could still be too big to attach to this forum. I could set up an FTP service, but it would be only temporary. Would one of  the EDF people be able to put larger files here if necessary?

Regards,

Brennan

[Alexandre Douce]

Yes Brennan, we can attach big files

For sending the files you can use also a file sharing web site like " sendspace ", " yousendit " or " mediafire ".

Thank you very much for sharing your work with all members of this forum!