Learning Forum

[bv169]

Hello,

I posted this question yesterday but it is gone from my history and in the Fluids channel forum. I read a previous thread in the old forum (no longer can find or access) discussing marangoni stresses at an interface between fluids. It seemed as though the answer was that no UDF or expressions are needed to model this, as both CSS and CSF have terms to calculate the changes in surface tension due to gradients, and therefore marangoni forces are already built into Fluent. Is this correct?

Thanks,
Breanna  

[Rob]

https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v221/en/flu_ug/flu_ug_sec_bc_wall.html%23flu_ug_sec_wall_marangoni  ?

[bv169]

Thank you, I cannot access that since I am a student but i will try to ask the account holder for our license if they can get me the information. 

[bv169]

I was able to access this. I knew that setting Marangoni on the wall was an option. I guess I should have clarified I meant specifically at the fluid interface, not at the wall boundary. I just wanted a certain answer since the Theory guide isn't 100% clear. 

[Rob]

The surface tension can be set as a function of temperature, but I think you'll need species effects too: that's not standard at present. 

[DrAmine]

You require temperature depedent surface tensuion + surface tension model and good mesh to keep track of interfacial motion due to the Marangoni stresses. 

[bv169]

Thank you. I found this UDF in the customization manual: /*************************************************************** Surface Tension Coefficient UDF for the multiphase VOF Model ***************************************************************/ #include "udf.h" DEFINE_PROPERTY(sfc,c,t) {     real T = C_T(c,t);     return 1.35 - 0.004*T + 5.0e-6*T*T; Which surface tension model should I use with it? CSF or CSS? Thanks, Breanna