Introduction to Turbulence Modeling

Comparison of Model Predictions

Conclusions (Existing Models)

• Available models can predict the mean flow properties with reasonable accuracy. Small adjustments of parameters are sometimes necessary.
• First-order modeling gives reasonable results only when a single length and velocity scale characterizes turbulence.
• The  model gives relatively accurate results when a scalar eddy viscosity is sufficient to characterize the flow. That is there is no preferred direction for example through the action of a body force.
• The stress transport models have the potential to most accurately represent the mean turbulent flow fields.

Deficiencies of Existing Models

• Adjustments of coefficients are sometimes needed.
• The derivation of the models are somewhat arbitrary.
• There is no systematic method for improving a model when it loses its accuracy.
• Models for complicated turbulent flows (such as multiphase flows) are not available.
• Realizability and other fundamental principles are sometimes violated.
• For example, the transport equations for