not conforming in pressure drop calculating using OpenFoam 7 and Ergun equation
 

Hi everyone
I'm new in OF7 and I tried to simulate compressible flow in a pipe with porous media using rhoPimpleFoam solver, but the calculated pressure drop form OF has major differences with Ergun equation.
I would appreciate it if anyone could help. Thank you in advance.

The pipe is 2 meters long and 0.05 meters in diameter




pvOptions file:


porosity1
{
type explicitPorositySource;

explicitPorositySourceCoeffs
{
selectionMode cellZone;
cellZone porosity;
active yes;
type DarcyForchheimer;
F 4148.1;
D 11111111.0;

d ($D $D $D);
f ($F $F $F);

coordinateSystem

{
type cartesian;
origin (0 0 0);
//rotation none;
coordinateRotation
{
type axesRotation;
e1 (0 1 0);
e2 (1 0 0);
}
}
}
}