transverse rotating magnetic fields
 

Hello,my dear friends,
My research refers to the influence of a transverse rotating magnetic fields to three-dimensional thermocapillary flow.I have been studing this by means of MHD for a long time. Unfortunately,I failed.
So I turned to the UDF to solve this problem.Now the question is how to express a second order partial derivative(electric potential to x-direction and y-direction) by UDF?And how to express a Laplace operator by UDF?
Hope for your answers and best wishes to you!
Thank you!