Hi to all, i am doing transient analysis of a pressure vessel type chambr.I am thinking from analysis that it may be case of highly seperated flow.so i want to use DES.i have not exp of using DES.so can anybody tell me how to use it?what are the requirements?what should be limit of courant no?I have read manual but it does not givr so much for that.ther are no tutorials regarding that.it says that ur mesh should be refined near wall region so DES can calulate seperated flow but how much?In my geometry it contains upto 5*1 m^2 lenth and width.i have used upto 7 lakh elements.How far i can go for DES?which parametrs should be cheked during run and after run?anyone's help would be highly appreciated. Thaks to all.

Hi, you shoud refer to j.paper 'The inner-outer layer interface in large-eddy simulations with wall-layer models' by U. Piomelli et al., Int. J. Heat and Fluid Flow, 2003.

There is also a paper called 'young person's guide to DES' or something like that. If I remember correctly it is from Spalart, but I am not really sure. You should search for that paper. Concerning the Courant number: CFX is an implicit solver. Consequently the limit for your time step is the timescale of the smallest vorticies you want to resolve.

Most important in my opinion is to realize the differences in the philosophy of RANS and the philosophy of LES.