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-   -   Shocktube help needed please (http://www.cfd-online.com/Forums/fluent/48888-shocktube-help-needed-please.html)

cfdguy08 July 28, 2008 12:34

Shocktube help needed please
 
Hi

I had posted already about my doubt of not plotting. But it seems nobody has faced such problem.

I suppose, there might be something wrong in the way i tried to do the simulation of shocktube.can someone gimme more hint.?

here is the procedure i followed to setup shocktube... such as ...... made a duct of L/D=10, unsteady, 2d, implicit, energy enabled, 2nd order upwind pressure inlet=500 kPa and pressure outlet=125kPa, and also patching with the same two pressures in two different zones, having one interface as interior. Iterate with 1e-5 and performed 2000 iterations. Grid=25,000 in one meshfile and another meshfile with gird=548,904 cells. both meshfiles were attempted but no useful result.

The residual is plotted and it shows me a series of high frequency sinewave, besides, it says it is converged whenever it is on the bottomside-axis of sinewave.

Am I missing something. The result doesnot show shock-propagation and also it doesnot plot.

Please help.

thanks

NRD July 28, 2008 15:15

Re: Shocktube help needed please
 
Since the flow needs to be treated as compressible, just wanted to make sure if you switched to ideal gas law?

cfdguy08 July 28, 2008 22:41

Re: Shocktube help needed please
 
yes sir, i did switch on the compressible by enabling ideal gas law.

Please gimme more details to resolve it..

I dont know where I am going wrong.

please help

Tepin Joe July 29, 2008 04:39

Re: Shocktube help needed please
 
Select Density Based Solver( Coupled Solver older version). Set density by ideal gas law. Rgds


jackmarlowe October 4, 2010 07:31

How do we patch different Pressure values to two neighbouring fluid zones?

I guess I am trying to solve the very same problem. I want to see an unsteady shock wave and an expansion wave in my shock tube analysis but I need two fluid zones with distinct pressure values.

Edit: Well I found how to do so, sorry for that. It was under where we initialize the solution. I patched different pressure values for driver and driven zones. It seems like it is a tough question thou, I am not sure which turbulence model to use. First tried Spalart-Almaras since the main concept is about fast flowing fluids but it had dozens of problems (divergence, turbulence, pressure). I am giving a shot to inviscid flow.


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