I am working on the simulation of a surface tension gradient by temperature gradient.
The relation between the temperature and the surface tension is represented in the variable called "Temperature derivative of the surface tension".
I am trying to add this variable as a function of T in COMSOL>Model builder>definitions>parameters.
However, the expression is marked red which means that there is an error, which I could not define.
And When I add a new variable at component>definition , the solver shows an error before starting the solution.
I will appreciate if you can help me with this problem.
Regards,
Ahmed
Look at this it may be helpful. Good luck.
https://www.comsol.com/community/forums/general/thread/18397/
Thanks Zoubair for your helpful answer.
Actually this link could solve the problem of adding a dependent variable to global variables. However, the solver also stops after 3 iteration with this error message :
"Segregated group 2 Attempt to evaluate non-integral power of negative number. - Function: ^
Failed to evaluate variable.
- Variable: gamma
- Defined as: ((((0.000457*((1-(comp1.T/(647*unit_K_cf)))^0.25600000000000001))+(0.00051400000000000003*((1-(comp1.T/(647*unit_K_cf)))^1.256)))*unit_N_cf)/(unit_K_cf*unit_m_cf))
Failed to evaluate expression.
- Expression: d((test(comp1.u)*gamma*comp1.Tx)*(dvol),{test@25})"
Dear Prof.Shiuh-Hwa Shyu,
Thanks a lot for your reply.
I totally agree with you.
I think attached document will be useful, if I am not wrong you are thinking of applying Marangoni Convection.
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