Solutions of Nozzle Flows by MacCormack Technique
From the cfd book of John Anderson, Jr, I have tried to follow the solution technique for convergingdiverging nozzle flows by using of MacCormack technique. But I found the problem about the purely subsonic case. This book did not show the solution of this case by using the governing equations in conservation form. So I have developed my code base on the governing equation in conservation form and it gave the correct !! solution for the case with normal shock (but the numerical solutions had some discrepancy). When I perform the purely subsonic case, the numerical solutions was wrongdiffer from the solution in the foregoing section of that book. My questions are 1. Can the governing equation in conservation form be used with subsonic flows? 2. If the answer of the first question is no, does it mean that the conservation equations are appropriate for case with shock only and the nonconservation equations are appropriate for the case without shock. 3. If the answer of the first question is yes, what is the possible error in my code? 4. Where can I find the excellent and clear explanation about using and caution of these two formulations of governing equations of fluid flow?

Re: Solutions of Nozzle Flows by MacCormack Techni
The governing equations (Euler equations I assume) are valid both for subsonic and transonic flows.
The MacCormack scheme isn't very good at cases with low Ma numbers though. If your Ma number goes below say 0.3 you will probably get stability/convergence problems with that scheme. 
Re: Solutions of Nozzle Flows by MacCormack Techni
Hi,
I programmed the scheme for CD nozzle. my inlet was supersonic and outlet was subsonic. The shock was best resolved by Roe's scheme. For low mach no. roe's scheme blows up bcos the jacobian of flux vector become near to singular....however maccormack works if more dissipation is added. Conservative form is the mother of all forms. It will work in any situation....compressible/incompressible,you must obiviously use correct the scheme. For compressible flows conservative form is recommended.However I have seen papers where people use finite difference for compressible flows( with some correction terms). Follow this link if you need to know more about conservative/nonconservative forms. http://personalpages.umist.ac.uk/sta...hydr/INDEX.HTM Also try other CFD books by Hirsch(this one is good), D.A. Anderon, Pletcher. Hope this helps. abhijit 
Re: Solutions of Nozzle Flows by MacCormack Techni
Hi, Maybe you will be interested to see my solution for technique presented in John Andersson book:
see: "PrandtlMeyer expansion wave solution" PDF file on my web page: http://panoramix.ift.uni.wroc.pl/~maq Maciek 
Re: Solutions of Nozzle Flows by MacCormack Techni
please send me the solutuions. thnk you.

Re: Solutions of Nozzle Flows by MacCormack Techni
i am a post graduate student.i am doing a course in CFD
let me know the solutions of the above problems edpecially "sub sonicsuper sonic flow in CD nozzle", if possible. 
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