Riemann Invariance
Hi everybody. I will appreciatte some help concerning the Riemann invariance at outer boundaries of an open domain. I am running an airfoil geometry in open domain and I have implemented the Far Field Boundary (based on lift and 1/4 chord). However, to finish this properly, I require a correct implementation of the Riemann invariance on the external boundaries. I've been trying this without any success. Any advice will be more than welcome.

Re: Riemann Invariance
Have you looked into Ch. Hirsch, a text book on CFD, (two volumes). There is a chapter on Boundary Conditions, I think it is Chapter 19 or 21.
You can find introductory remarks and methods for invariance. Also the book gives good references. I feel it would be a good starting point. Bye K. Sundar 
Re: Riemann Invariance
Hi Javier, there is also some litterature on that, that might be helpfull since it gives specific example of how to apply/implement the BC on the Riemann Invariants (the characteristics of the flow). A good starting point would be the book of Landau, Lifshitz, 1987, Pergamon press, Fluid Mechanics. Then I would suggest to have a look at Gottlieb, Gunzburger, Turkel, SIAM J. Numer. Anal., vol.19, p.671 (1982). See section 5 of the article (but read also the rest). You can also have a look at Godon and Shaviv, 1993, Computer Methods in Applied Mechanics and Engineering, vol. 110, p. 171. There is a good detailed treatment of the BC on the Riemann Invariants there as well as many good references to it. I hope this helps. Cheers, Patrick.

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