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-   -   Convergence problems for a Scramjet application (http://www.cfd-online.com/Forums/fluent/28866-convergence-problems-scramjet-application.html)

Jeff McGuire August 29, 2001 02:29

Convergence problems for a Scramjet application
 
The problem which I am trying to simulate is for a Scramjet in a Mach 6.6 freestream flow. The highest Mach number for which the solution will converge is about 3, but anything above this causes error messages to appear. Changing the solver to 'coupled explicit' no longer produces any error messages, but the solution still will not converge to the required limits. I'm not sure if there is an obvious solution to this problem as I've only been using Fluent for a few weeks, but I'd appreciate any suggestions. Thanks.

david August 30, 2001 00:48

Re: Convergence problems for a Scramjet applicatio
 
A) U have to follow up whether there is any shock in the domain while getting any solution B) Adapt the grid where you have sudden variation of solutions parameters C) Try to find out where is the maximum residuals.

DC

John C. Chien September 2, 2001 01:58

Re: Convergence problems for a Scramjet applicatio
 
(1). It is a difficult problem to solve at high Mach number, and even the recent flight test of the SCRAMJET vehicle was not successful.(not due to the SCRAMJET itself but due to the more conventional rocket launch vehicle, as the report said) (2). I think, the initial flow field is very important to get any code started, and after that, you will have to chase after the wave propagation throughout the flow field. (3). These flow features are always sensitive to the mesh size and distribution.


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