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Con-Div Nozzle Shock structure problem

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Old   October 29, 2010, 02:26
Exclamation Con-Div Nozzle Shock structure problem
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padhu
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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
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Old   November 15, 2010, 02:28
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Chris, Kam
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I have same problem


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
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Old   November 16, 2010, 03:37
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padhu
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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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