Simulating lorentz force in electrochemical cell

Dave

Hi, I am simulating the Lorentz Force(F bar->denoting vector) using the relation => F bar = J bar x B bar;(cross product), where J bar = current density vector, B bar = magnetic field vector. I have a few queries - [1] how to introduce the magnetic field vector in a particular direction I want. [2] Using Fick's Law of Diffusion in electrochemical cell, I have calculated current density from concentration gradient at electrode surface. [3] My understanding is that I have to write a DEFINE_SOURCE routine to calculate the cross product of the two vectors, i.e the Lorentz force.

Please request you to help me out on this as I am new to this field.