151-0114-00L  Turbulence Modeling

SemesterFrühjahrssemester 2014
DozierendeD. W. Meyer-Massetti
Periodizitätjährlich wiederkehrende Veranstaltung
LehrspracheEnglisch


KurzbeschreibungIn the study of turbulent flows the objective is to obtain a tractable quantitative theory or model to calculate quantities of interest. A century of expertise has shown the 'turbulence problem' to be notoriously difficult, and there are no prospects of a simple analytic theory. In this class, five of the leading computational approaches to turbulent flows are described and examined.
LernzielThe goal of this class is to give an good overview of current turbulence modeling approaches, but also to help developing a feeling for advantages and limitations of the various classes of models.
Inhalt1. Introduction to Modeling: The goal here is to present an overview of different approaches, point out the main challenges and discuss general criteria for turbulence models.

2. Direct Numerical Simulation (DNS): After the basics of DNS are introduced, applications to homogeneous and inhomogeneous turbulent flows are discussed.

3. Turbulent-Viscosity Models: The turbulent viscosity hypothesis and the implications due to the underlying assumption are explained and discussed. Then, specific models belonging to the classes of algebraic, one-equation, and two-equation models are introduced.

4. Reynolds-Stress Models: After a brief discussion of the concept and the advantage above turbulent-viscosity models, most of the time will be spent for "return-to-isotropy models, near-wall treatments and algebraic stress models.

5. Large-Eddy Simulation (LES): The basic concepts of LES are introduced. After a discussion of filtering, the filtered conservation equations are derived. As an example of a sub-grid model the Smagorinsky model is presented and finally the perspectives of LES are discussed.

6. Probability Density Function (PDF) Methods: First, the concept of PDF modeling is explained and the PDF transport equation is derived, discussed and analyzed. It is shown that turbulent transport and reaction source terms appear in closed form. Then, consistent Lagrangian models are presented. Using these equations and models, corresponding Reynolds-stress models are derived.
SkriptThe course is partly based on part two of the book "Turbulent Flows" by Stephen B. Pope published by Cambridge University Press, 2000. In addition, we hand out a manuscript, which contains not all the course material, however.
LiteraturS. B. Pope, Turbulent Flows, Cambridge University Press, 2000