Hallo,

I precise my question. I try to understand what turbulence is. In this matter it seems me, that there are a lot of tubulence models, but what model is the best in connection to compute e.g. separated flows ?

It would help me to find a book or a nice paper about this topic.

Regards Burkhard

Read Tennekes and Lumley (1972) just to get started!

(1). There are some standard books you can read, a). Wilcox,D.C. "Turbulence Modeling for CFD",1998, b). Launder & Spalding,"Lectures in Mathematical Models of Turbulence",AP 1972, c).Hinze,J.O.,"Turbulence",McGraw Hill,1975, d). Schlichting,"Boundary Layer Theory",McGraw Hill. e). Rodi,W, Review Paper on Low Reynolds number models in AIAA Journal, (2). What Separated Flows? So far, there is no single Universal Turbulence Model to fit all applications. (3). If you'd like to get some hands-on experience, try any available commercial CFD code first for your separated flow problems. Try it and you will like it.

please send me the detail information regarding analysis of francis/kaplan/pelton turbines using cfd software.I will be thankfull for your reply.

Thanking you,

Fathfully your's vilas gumbade

turbulence is not turbulence modelling and vice versa before you studt turbulence modelling you need to study turbulent flows. if you haven't done so already you can take a course in turbulence at a nearby university. there aren't many books out there on turbulence modelling and some may be biased toward certain turbulence models because of the author's own bias. also i've found that papers on turbulence modelling do not let you understand the developers motivation and thinking in developing the model. they tend to start apparently halfway there and then derive some equations using a lot of order of magnitude arguments and some correlation with experimental data (or more often today DNS data) which may or may not match. i'd say you can simulate separated flow with any of the one (Spallart-Allmaras) or two (k-e, k-w) equation models or any of the Reynold's stress models (algebraic of differential). there are also one and a half and three equation models in the literature. as for the quality of your results only you can decide. for some flows one or the other or none of these models may work. some times you can tell a priori whether a model can work for a given flow. eg eddy viscosity models should really only be used where the mean stress has only one dominant direction etc.

Hello,

a very good place to start is with Rotta's book:

Rotta, Julius C., 1912- Turbulente Strömungen; eine Einführung in die Theorie und ihre Anwendung. Stuttgart, B. G. Teubner, 1972.

Which I suspect you will have no trouble reading.

In fact much of the later work on the turbulence modelling is based on his early work!

Regards, Duane