An OpenFOAM solver for porous media needs help
 

Hello, everyone, I developed a OpenFOAM solver for porous media, based on stressAnalysis-solidDisplacementFoam (OF version 4.x), It aims to solve two coupled equations about two variables(scalar p and vector U).
When I used this solver to solve a specific initial & boundary value problem, it is found that when the input parameter Sr=0.95 (so that coefficient Dp1=0.0266562,Dp2=2.61497E6), the calculation is successful and proceeds to the predefined end time, though the result is not correct(p field only varies within the very thin boundary). However, when I changed the parameter Sr from 0.95 to 1.0 with other parameters kept, the calculation broke down at the first time step and the initial residual of p could not be reduced form 1.0 as the iteration proceeded.
I guess that the problem results from the solving of the equation system. Could anybody give me any suggestions?
I want to attach the corresponding files for reference. But the "Attachments" button does not work. Could anybody tell me how to attach? Thank you all!