[Samples] Fix handling of porosity in WSR-chain PFR example

samples/python/reactors/surf_pfr.py

@@ -54,7 +54,7 @@
 # catalyst area in one reactor
 cat_area = cat_area_per_vol * rvol
 
-mass_flow_rate = velocity * gas.density * area
+mass_flow_rate = velocity * gas.density * area * porosity
 
 # The plug flow reactor is represented by a linear chain of zero-dimensional
 # reactors. The gas at the inlet to the first one has the specified inlet
@@ -96,11 +96,6 @@
 v = ct.PressureController(r, downstream, master=m, K=1e-5)
 
 sim = ct.ReactorNet([r])
-sim.max_err_test_fails = 12
-
-# set relative and absolute tolerances on the simulation
-sim.rtol = 1.0e-9
-sim.atol = 1.0e-21
 
 output_data = []