Porous Coefficient and its direction Vector
 

Hello All,

I have worked with Catalytic Converter in Exhaust System. We normally model, catalyst as porous zone.

the inlet of the porous zone is align to the micro tubes of the catalytic converter and hence giving the direction vector and viscous and inertial coefficient was quite easy. since the micro tubes was align to one axis and gas flow parallel to the micro tubes.
But, now suppose we need to model a porous zone which is sponge type in nature, then how should the inertial and viscous coefficient in direction 2 and 3? Does the coefficient value in depends on material and the micro structure of porous zone(in real life not the cad structure).

Also, how to to decide the direction 1 and direction 2 for any catalysts. Doe it depend on the micro structure of catalyst or the inlet plane direction?

for eg: suppose we take a catalytic converter which have radial tubes/vanes and flow is enter tangential for one end and leaving axially from other end ( kind a like a centrifugal pump). then how should we decide the the direction vector and the coeficient value ?