Large-Eddy Simulation of Turbulent Flows

(ME EN 7960-003)  Fall 2014


Instructor: Rob Stoll, Ph.D
Department of Mechanical Engineering
581-3405
rstoll@eng.utah.edu
Credit Hours: 3 credit
Lecture: T, Th 3:40-5:00
Room: WEB 2470
Office Hours: KENN 1012 by appointment (check my calendar & email or just stop in)
Web Site: http://www.eng.utah.edu/~rstoll/LES/
Recommended
Texts:
B. Geurts (Edwards, 2004)
P. Sagaut  and C. Meneveau (Springer-Verlag, 2005)
S. Pope (Cambridge University Press, 2000)
Required Prerequisites: ME EN 6700 or Instructor consent
Good to have Prerequisites: ME EN 7710, ME EN 7720

Course Description:

This course covers topics related to Large-Eddy Simulation (LES). An advanced Computational Fluid Dynamics (CFD) technique. LES is quickly replacing traditional Reynolds Averaged Navier-Stokes (RANS) modeling as the method of choice for researchers and practitioners studying turbulent fluid flow phenomena in engineering and environmental problems.  LES explicitly solves for the larger scale turbulent motions that are highly dependent on boundary conditions (e.g., geometry, large scale forcing) while using a turbulence model only for the smaller (and presumably more universal) motions.  This is a distinct advantage over traditional RANS models where the effects of turbulence on the flow field are entirely dependent on the turbulence parameterizations.

This course will provide students with an introduction to the concepts and principles of the LES technique for numerical simulation of turbulent flows.  The course will start by discussing filtering and the turbulence closure problem in the context of LES.  It will then move on to derive and examine the filtered forms of the governing equations.  Modeling the effect of unresolved turbulence, with SubGrid-Scale (SGS) models, will constitute a significant portion of the course content.  Students will learn how to formulate SGS models, how to test SGS models off-line with experimental data and evaluate the performance of SGS models from the results of turbulent flow simulations.  The last part of the class will examine issues pertaining to LES of specific flow cases of interest to the class.  For example, this might include wall-boundary conditions for wall bounded flows , turbulent inlet and exit conditions, SGS models for high-Reynolds number flows, Lagrangian particle methods for LES, and SGS modeling for turbulent reacting flows.  Time permitting, other topics specific to student interests will be covered.

Course Objectives:

Course Outline:

Grading:

Grades will be based on a series of homework assignments and two course projects.  The grades in each of these categories will be broken down as follows:
Homework 40%
Project #1 25%
Project #2 35%

    Homework:
Approximately 3-4 homework assignments will be given during the semester. These assignments will focus on basic topics and ideas that will be needed in the projects (statistics of turbulence, filtering, power spectra estimation, model formulations, etc.).  The assignments will be given throughout the semester when material is covered with an emphasis on the time period before the 1st project.

    Project #1 (tentative):
Project #1 will focus on the application of LES SGS models in 3D turbulence simulations.  Students will be provided a basic 3D numerical code which they will add their own SGS models to and will then examine the effect of base model type, model coefficient specification and grid resolution on the resolved simulated velocity fields.  The project will be submitted in the form of a short report (~4 pages) outlining the basics of the simulation code used, the chosen SGS models and the results of parameter studies.

    Project #2:
Project #2 will consist of gaining experience on doing a priori analysis of LES SGS models from experimental or numerical data.  Data sets from various experimental setups (high speed turbulence sensors, PIV) or high resolution DNS will be provided for students to use in the projects based on the students research interests.  Alternatively, if students have appropriate data sets (experimental or numerical) that they wish to use for their project they will be free to do so. The project will be submitted in the form of a short report  (~4-6 pages) including: basics and background of the SGS models to be tested, a short description of the data set used in the analysis and a short summary of key results/incites gained from the tests.  In addition to the project report, all students will be required to give a short presentation (~15 minutes) during the last weeks of class.  

Useful Information: