Turbulent Flows Course-Basic Concept, Modeling and CFD Simulation
A basic course on Turbulence Concept, Modeling and CFD Simulation including basic turbulence models such as k-e and k-w and advanced and complicated turbulence models such as RSM and turbulence-resolving methods such as LES, DES, PANS.
Organizer: World-Academies, Knowledge Management Startup at Technical University of Dresden, Germany
Course content
The physics of turbulence, molecular and eddy viscosities concepts and scales, energy cascade and budget of turbulent motion will be discussed. The Reynolds Averaged Navier Stokes (RANS), Turbulent Shear Stress and the clouser problem will be discussed towards introducing zero and two equation models (K-e, K-w, …). Reynolds Stress Models (RSM) also will be introduced in some detail. Different modeling approaches will be discussed and practiced for CFD simulations.
Turbulence-resolving methods will be discussed including:
- LES (Large Eddy Simulations).
- URANS (Unsteady Reynolds-Averaged Navier-Stokes)
- DES (Detached-Eddy Simulations)
In LES the Navier-Stokes equations are filtered over a small volume (usually the computational cell). Thereby the dependent variables are split into one subgrid part (turbulent fluctuations smaller than the cell) and one resolved part (turbulent scales which are resolved by our numerical method)
Lectures:
| Introduction | ||
| Lecture1 | Turbulence Basic Concepts, Definition and Specifications, Modeling Approaches, Large and Small Eddies, Energy cascade and process created by vorticity, Types of Turbulence, l Time averaged Navier-Stokes, Closure Problem | |
| Lecture2 | Scales in Turbulence, Vorticity, Vortex and Eddy concepts, Correlation function for estimation of eddies distribution size, Kolmogorov Hypothesis on eddies size and energy cascade. Types of Turbulent Flows, Homogeneity & Isotropic properties, Direct Numerical Simulation(DNS), required mesh size and time step as the function of Reynolds, Averaging in space and time towards RANS modeling | |
| Turbulence Models | ||
| Lecture3 | Turbulence Models Introduction, Boussinesq Assumption, Eddy-viscosity Zero Equation Models, The Modelled k Equation, One Equation Models | |
| Lecture4 | Two-Equation Turbulence Models, Wall Functions, K-e and K-w Models, Transport Equation for Turbulent kinetic energy, Spatial vs. spectral energy transfer | |
| Lecture5 | Low-Re Number Turbulence Models, Low-Re K-e & K-w Models, Non-Isotropic K-e | |
| Lecture6 | Boundary Conditions in Turbulence, Inlet/Outlet Conditions, Wall Functions, K-e values at boundary layer, Wall Treatment B.C., Low Reynolds (near wall) K-e and K-w models. | |
| Lecture7 | Turbulence CFD Simulation 1: RANS, k-omega, k-epsilon (Computational Code Programing, Open Foam, SimScale/Ansys) | |
| Lecture8 | Renormalized Group (RNG) , Shear Stress Transport (SST), Reynolds Stress Models (RSM) Turbulence Modeling, concepts, methodologies and applications. | |
| Large Eddy Simulation | ||
| Lecture9 | Large Eddy Simulations Time averaging and filtering, Differences between time-averaging (RANS) and space filtering (LES)Resolved & SGS scales, The box-filter and the cut-off filter, Highest resolved wavenumbers | |
| Lecture10 | Large Eddy Simulations (Cont.) Subgrid model, Smagorinsky model vs. mixing-length model RANS vs. LES One-equation ksgs model, Smagorinsky model derived from the ksgs equation, A dynamic one-equation model, A Mixed Model Based on a One-Eq. Model, Applied LES Resolution requirements | |
| DES: Detached Eddy Simulation | ||
| Lecture11 | DES DES based on two-equation models, DES based on the K-w SST model, DDES Hybrid LES-RANS Momentum equations in hybrid LES-RANS, The one-equation hybrid LES-RANS model | |
| Lecture12 | Turbulence CFD Simulation 2: LES Open Foam Programing, SimScale/Ansys |
Prerequisites
- Fluid Mechanics or Viscous Fluid Flow, CFD or some related courses
- Familiar with some software (Open Foam, Ansys Fluent, .. Coding, )
Selected References:
1- P. A. Durbin and B. A. Pettersson Reif “Statistical Theory and Modeling for Turbulent Flows” 2011, Second Edition.
2-Davis C. Wilcox “Turbulence Model for CFD” 2006, third edition.
3- S.B. Pope. Turbulent Flow. Cambridge University Press, Cambridge, UK, 2001.
4-H. Tennekes and J.L. Lumley. A First Course in Turbulence. The MIT Press, Cambridge, Massachusetts, 1972.
5- P. Bradshaw. Turbulence. Springer-Verlag, Berlin, 1976.
6- Papers, Reports and Slides given you during the course.
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