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-   -   [Q] Steady Compressible High Reynolds Problem. (http://www.cfd-online.com/Forums/cd-adapco/52368-q-steady-compressible-high-reynolds-problem.html)

Ryu, Sung Min March 2, 2000 22:23

[Q] Steady Compressible High Reynolds Problem.
 
Problem : Steady Inviscid Compressible Model : NACA0012 2D airfoil(Chord length = 1) Conditions : Reynolds Number = 8.e6, Mach Number = 0.76, angle of attack= 1.43 degree Mesh : 164 X 84 O-type Grid

Under above conditions, Shock is seen at 0.4 chord length on upper surface by experiment results and other numerical results. But I can't see the same result by STAR-CD. I see the shock at 0.95 chord length. I wonder that STAR-CD can solve exactly the high Reynolds number problems like this.

Questions: 1. Is there any other boundary condition available in STAR-CD to describe Subsonic Freestream condition ? (I used Inlet Boundary condition) 2. Can STAR-CD capture the shock exactly? 3. The mesh used is very dense near airfoil surfaces. The smallest mesh size is of order 1.e-5. Is it OK in STAR-CD ?

Dean Hawkinson March 27, 2000 15:55

Re: [Q] Steady Compressible High Reynolds Problem.
 
I am running a very similar case. I also used inlet b.c. I've had the same problem but tightening the convergence criteria seemed to help. Unfortunately, I've been seeing a lot of smearing of the shock. Suggestions would be welcome.

Good Luck

Dean

John C. Chien March 31, 2000 12:46

Re: [Q] Steady Compressible High Reynolds Problem.
 
(1). The answer is very simple: ask the code vendor to provide a benchmark test result of a transonic flow over an airfoil with shock. (2). This is the only way to find out whether the code can or can not pass the validation phase. If the vendor can provide the report or paper, then you can try to repeat the test result on your own. Hopefully, at the end of your own test, you will have the answer you are looking for.


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