(Note: Problem Solved)
I am trying to define the phase field equation in the picture, using Coefficient form (or maybe convection-diffusion) PDE in COMSOL. However, I have a problem defining the second line, as there is no equivalent for these two terms in the COMSOL pre-defined equation. How would you do that?
#COMSOL #PDE #Phase-Field #PF #phasefield
Perhaps you can try and write it in weak form instead. Looks complicated though ...
Dear Farhad Sadegh Moghanlou and Mohammad Vajdi ,
Could you help Mehdi Akbarifar please?
Thanks.
This should be possible to write using the source term and with the help of mathematical forms in Comsol for differentiation.
René Christensen I have tried it, didn’t work.
Mehdi Shahedi Asl thank you 🙏🏼
Saeed Baghaee Ivriq It will be great!
Lubhani Mishra
Yes, Thank you!
I did the exact thing yesterday and it is working. However, I have problem defining Theta!
I have tried to define it as (atan(d(phi,y)/d(phi,x)), but it doesn’t work since it causes a dividing by zero. This happens because phix and phiy are zero everywhere but the same inteface. Any idea on how can I correct it?
Fortunately, I successfully managed to implement ad discretize the PDE. Also, determining the interface curvature was successfully done adding a conditional initial condition. for those who face the similar problem in the future, I'll be more than happy to help.
Dear Boxue Song
First of all, I suggest using the Coefficient model.
Then, if your phase field variable is Phi, change the dependent variable name in the Coefficient form PDE to phi. in this way, you can easily call the derivations by the terms like phix for (dphi/dx) or phit for (dphi/dt) and so on.
then, if you have defined the W in the variables, change Wd to d(w,t) if it is a derivative of time.
you need to couple this with another PDE, defining the change of U over t.
I recommend the one in the picture.
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