"WATER HAMMER" Roe's method

ROOZBEH

Hi;

I want to simulate one dimensional water hammer flow. I have modeled this problem by method of characteristics. I want to use Godonov type method. I have some questions: Can I use reiman exact solution? For Roe's method, what Z matrix should I use? My variables are (v,p). For Euler equation we use [(rho)^1/2 *(1,u,E)] as Z matrix. What should I do for watter hammer equations?

Thanks

ROOZBEH