The
porous media capabilities of Flow Simulation are used to simulate each catalyst, which
allows you to model the volume that the catalyst occupies as a distributed resistance
instead of discretely modeling all of the individual passages within the catalyst, which
would be impractical or even impossible. Here, as a Flow Simulation tutorial example we
consider the influence of the catalysts' porous medium permeability type (isotropic and
unidirectional media of the same resistance to flow) on the exhaust mass flow rate
distribution over the catalysts' cross sections. We will observe the latter through the
behavior of the exhaust gas flow trajectories distributed uniformly over the model's inlet
and passing through the porous catalysts. Additionally, by coloring the flow trajectories
by the flow velocity the exhaust gas residence time in the porous catalysts can be
estimated, which is also important from the catalyst effectiveness viewpoint.