Modification of Resistance coefficients when applying to different geometry thicknesses of the porous medium zone.
Coefficients once calculated from the Experimental values are set for a specified pressure loss per unit length/thickness (in the direction).
No alterations are needed when thickness/length in domain is changed. Ansys Fluent takes care of the thickness/length and computes the correct pressure drop.
To explain: For example: experimental values of pressure drop for domain thickness/length of 1m are used to calculate the coefficients. But porous region (in computational domain) is of 500 mm in thickness/length. Still Ansys Fluent will compute the correct pressure drop across the 500 mm thickness/length using the already calculated coefficients. Therefore, there is no need to alter the coefficients for variable porous region thickness/length.
For more details refer to this document