Hi, I'm trying to simulate the Fitzhugh-Nagumo model of neurons on COMSOL 5.3a, exactly as it was done in the article "3D-Simulation of Action Potential Propagation in a Squid Giant Axon" by Appali et al. I'm trying to put in the equation for numerical flux for Equation 1 (Equation 4 in the article) as shown below:
In which I assumed the upper triangle operator is the Laplacian, hence I put in the following in the General Form PDE Interface: u1xx+u1yy+u1zz+(alpha-u1)(u1-1)u1-u2+I
& I get Inconsistent Units problem. I set the units for u1 & u2 to be Volts (V).