# Residual Oscillations

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 February 4, 2006, 06:57 Residual Oscillations #1 Cyril Guest   Posts: n/a I'm working on a bullet (Shock wave studies). I'm trying to find the best method to find a good model of the shock wave. I'm trying with inviscid, laminar and spalart allmaras. But in the 2 first cases, the residuals start to oscillate more or less, depending of the method. Could somebody help me to make theses residuals not to oscillate ?? You can see the mesh and the residuals here : http://img510.imageshack.us/img510/3...nstitre0up.jpg Thanks ! P.S : If you have any suggestion about a model, or anything else... I'm very interested !

 February 6, 2006, 03:40 Re: Residual Oscillations #3 Cyril Guest   Posts: n/a Thank you very much for this. It helped me to understand well some aspects of numerical simulation. The fact is that I'm finishing my studies, and I've never been taught about numerical calculus during my scholarship (engineering school), and some aspects of it are very difficult to get! May I ask you an other question ? In your posts, you often talk about "first and second run"… Does it means that you "do" a first run, quick and unrefined, and then you start another one, more refined, based on the previous one ? How do you do this ? Because for the project I'm working on (end of study project), I decided to run my calculus on the following scheme : 1-invicid, 2-laminar, 3-SA or k-e (std&hellip Do you think that's a good idea ? (The purpose of my question, is that I can't find the same results with Fluent and {Whitham method and experimental tests results}). Factor 10 higher in Fluent ! Regards, Cyril

 February 6, 2006, 03:42 Re: Residual Oscillations #4 Cyril Guest   Posts: n/a Moreover, when I try to iterate with K-e Rzable, I've got a "turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 28 cells"... (I work with ideal gaz) Do you think It could come from my boundaries conditions (Pressure far field and pressure outlet) ?