Majority of flows in nature and in engineering applications are turbulent. Turbulent flow fields are three dimensional, chaotic, diffusive, dissipative, and random. These flows are characterized by velocity fluctuations in all directions with infinite number of scales.

Presently, turbulence modeling based on Reynolds-Averaged Navier Stokes (RANS) equations is the most common and practical approach for turbulence simulation. RANS are time-averaged modification of Navier-Stokes equations and turbulence models are semi-empirical mathematical relations that are used to predict the general effect of turbulence.

The objective of turbulence modeling is to develop equations that will predict the time-averaged velocity, pressure, and temperature fields without calculating the complete turbulent flow pattern as a function of time. Unfortunately, there is no single universally accepted turbulence model that works for all flows and all regimes. Therefore, users have to use engineering judgment to choose from a number of different alternatives sine the accuracy and effectiveness of each model varies depending on the application.

Course Content

• Understanding turbulence
• Turbulence energy cascade & vortex stretching
• Turbulence scales
• Turbulence generation and destruction
• Discussion on DNS & LES
• Turbulent stresses
• RANS simulation
• Turbulence modeling
• First order models: One-equation & Two-equations models
• Wall integration & wall function
• Detached eddy simulation
• URANS
• Model comparison: advantages and disadvantages
• Model Validations