In Comsol 4.3a the diffuse scattering boundary condition is incorrect. it generates an angular distribution with respect to the surface normal of cos(theta), while the correct distribution is cos(theta)*sin(theta). In equation view you see that theta is is chosen by
theta = acos(0.5+random(xxx))
the correct expression is
theta=acos(sqrt(0.5+random(xxx)))
see J. Greenwood, Vacuum 67 (2002) 217–222
Comsol support showed me how to fix this in equation view. The original expression is incompatible with detailed balance
theta = acos(0.5+random(xxx))
the correct expression is
theta=acos(sqrt(0.5+random(xxx)))
see J. Greenwood, Vacuum 67 (2002) 217–222
Comsol support showed me how to fix this in equation view. The original expression is incompatible with detailed balance