6.3.2. STEP 2 : Perform simple changes

Modify the source file as well as the INITGAZ.DAT file to easely change the initial condition. Implement the next:

• Solution of an uniform flow : intial conditions constant in pressure, density and velocity (even zero velocity is admissible), but take care of the boundary conditions…

Hint

Save the solution of the shock tube problem in a file named fo exemple solref : after every modification in the 1D code the plots must exactly recover this solution. Do not hesitate to open the PLOT file and compare exact values with solref : sometimes small differences in values are not visible on the plots but they may indicate unwanted or uncontrolled changes…

At the end of this step 2 you should know:

• What are the unknowns and in which vectors they are stored.
• Where are the fluxe computed This is not useful to know how the Riemann solver works!.
• Where and when are plotted the solution.
• Where is the finite volume relation given Eq.1.6 in the code.
• How is defined the mesh.