continuity and momentum equations
 

hello, I'm quite new in CFD....sorry for my ignorance

I'm trying to solve the momentum and continuity equations together.
Is that possible?


I'm trying to model on MATLAB the ventilation of a tunnel, therefore I would like to introduce the pressure outside and obtain a velocity field.

To start I'm going to model it 1-D therefore I'll use a finite difference scheme.

what will be my equations in the finite difference scheme?
I've tried a upwind scheme and.....E+12
the convergence is not very nice.

I've taken into account CFL.

Shall I use a space centered, implicit/explicit,C-N?????
HELP