[bzz77]

I'm a newbie to fluid dynamics, so sorry if this is a silly question.

I am using a program for solving the transient pressure equation. The program is based on the finite element method. I use the results to calculate a velocity field.

I have tried to derive the finite element formulation myself, to make sure I understand how the code works. The problem is, my results are not consistent with the formulation the program uses. The program uses mass mobility as the conductance term and compressibility as the capacitance term. I get the opposite in my derivation.

I'm pretty sure that I must have done something wrong somewhere, but I'm at a loss. I would be very grateful if someone would confirm whether I'm right or the program is, and put me on the right track (maybe by directing me to a text-book/online derivation or by providing a quick explanation). Thanks for any help.