The aim of the course is to allow students to acquire a critical view of numerical strategies for the modelling of turbulence (both developed and in transition), both of RANS type and of LES type. The expected result is a consequent mature use of such numerical strategies, based on the awareness that simulations are not the real thing but a sophisticated modeling of it and, as such, susceptible to errors, sometimes relevant.
The program is divided between lectures and guided tutorials. At least one lecture will be delivered on every topic, and to reinforce the knowledge acquired, we will conduct numerical simulations or analyze data using modern software and applications.
1. Transition to turbulence in shear flows.
2. CFD and turbulence modeling. Introduction to turbulence. Turbulence, does it matter? The nature of turbulence. Wall bounded flows and free shear flows.
3. Length scales in turbulent flows. From Kolmogorov scales to Taylor microscales to integral scales. Energy cascade. Law of the wall. Near wall treatment.
4. Practical turbulence estimates.
5. Governing equations. Reynolds averaging. The Boussinesq hypothesis. Reynolds-averaged Navier-Stokes equations (RANS).
6. Closure problem. Algebraic models. One equation models. Two equation models. Reynolds stress models (RSM). Unsteady RANS simulations (URANS). Wall modeling and wall resolving simulations.
7. Statistical description of turbulence. Descriptive statistics. Joint statistics. One-point correlation. Two-point correlations. Time series. Turbulent kinetic energy spectrum. Power spectrum.
8. Post-processing turbulent simulations. Quantitative and qualitative post-processing. Dealing with steady and unsteady simulations.
9. Beyond the Boussinesq hypothesis, compressibility effects, and multiphase flows. Effect of roughness on the law of the wall.
10. Scale-resolving simulations (SRS). DES, LES, DNS. Wall modeling and wall resolving simulations in SRS.
11. Best practices in CFD and turbulence modeling. Numerical considerations. Validation and verification. Mesh dependency studies. Accuracy and reliability of turbulent simulations.
Ricevimento: 10:00-16:00 – Monday to Thursday Confirm appointment by sending an email to Joel Guerrero – joel.guerrero@unige.it
JOEL ENRIQUE GUERRERO RIVAS (President)
ALESSANDRO BOTTARO
TURBULENCE AND CFD MODELS
For the hands-on sessions, students should bring her/his computer with all the software installed. All the software to be used is free and can be downloaded at the links provided.