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-   -   Con-Div Nozzle Shock structure problem (http://www.cfd-online.com/Forums/fluent/81522-con-div-nozzle-shock-structure-problem.html)

padmanathan October 29, 2010 02:26

Con-Div Nozzle Shock structure problem
 
Dear All,

I'm working in simulation of supersonic flow through Nozzle.

I need to simulate shock structure at the exit of the nozzle.

My problem is, I need to simulate normal shock at the exit. for that I have calculated the exit pressure using the normal shock relation (analytically). when i am using the calculated pressure the solution diverges. I observed that the shock is found upto certain iterations, and suddenly the solution diverges.

What kind of boundary conditions have to be choosen?
What may be the appropriate pressure ratio suitable for this problem?
In case, If I am increasing the nozzle length do i can able to capture the shock?

The Simulation specifications are,
Nozzle Length = 3.1 m , Throat is at 1 m from inlet, Area ratio (Aexit/A*) = 2.53, Designed Mexit = 2.53.
The solver details are, density based, implicit, axi-symmetric, steady, inviscid flow.

Thanks in advance,
padmanathan

cartman November 15, 2010 03:28

I have same problem :D


and I tried...



It's Unstable but I did with "pressure_far_field" conditions, in Ambient.

I'm sure that there be more nice solution

padmanathan November 16, 2010 04:37

thanks for your reply, chris.

by now, i changed my solution from second order upwind scheme to first order scheme. now i can able to simulate by increasing the back pressure upto some level. and in order to follow first order scheme, i doubled the grid resolution to maintain the accuracy.


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