# LES

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 March 2, 2004, 00:29 LES #1 Jessica Guest   Posts: n/a I am starting to write an LES code of mine. I am using the finite volume, staggered grid arrangement, SIMPLE algorithm for solution of the Navier-Stokes Equations. Unfortunately, I dont understand where (in the algorithm) I shall be filtering my primary variables, to calculate the SGS. 1. Anyone have any practical insights on developing a Smagorinsky type LES code? 1b. How does the filter type come into consideration? 2. Anyone ever built his/her own dynamic model (Germano) -- how did you implement the test filter?

 March 4, 2004, 07:28 Re: LES #2 jdc Guest   Posts: n/a Hi Jessica, Have a look for previous discussion on the subject in this forum. 1) You need to pay attention to (a) the numerical method; (b) the treatment of the boundary conditions. 1b) In general, a LES code does not "explicitely" filter the variable. The filtering operation is "implicit" and based on your mesh resolution. This apply unless the purpose of your work is to study the effect of the fileter. 2) There is various approach for the test filter that are all +/- based on averaging your quantities using (a) the neighouring cells (compact/extended molecules), (b) a Laplace operator (see book Sagaut, Large Eddy Simulation for Incompressible Flows). It will take more time to test and run that to code! Note: Jay (see more recent posting) and you seems to be working separately on the same subject. Why not contact him and share info? Have fun and keep inform. Julien

 March 23, 2004, 09:39 ?? #3 amit rao and yogesh Guest   Posts: n/a jessica we have made one dimensional cd nozzle code using McCormack's scheme. u must be thinking that this is quite elementary, but we r strating things .. we want to know that which scheme is best suited to simulate flow over an airfoil ( which is a two dimensional problem) please guide us for the same. sophomores from india.

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