k-epsilon and LES approximate unresolved turbulent fluctuations.
Turbulent eddies span many scales. Reynolds-averaged (RANS) models (k-ε, k-ω SST) solve mean flow with modelled eddy viscosity; LES resolves large eddies and models small ones; DNS resolves all scales at huge cost. Selection trades accuracy and computational effort.
RANS is the industrial standard for aerodynamics and HVAC.
Turbulence models approximate the effect of small eddies in simulations, so they make it possible to predict turbulent flows on computers.
k-epsilon and LES approximate unresolved turbulent fluctuations.
Turbulence models approximate the effect of small eddies in simulations, so they make it possible to predict turbulent flows on computers.
It solves transport equations for turbulent kinetic energy and its dissipation rate, which gives the eddy viscosity for the mean flow.
Resolving all turbulent scales requires enormous computing power, so models represent the unresolved part.
Typical applications include choosing a turbulence model for an external aerodynamic simulation, predicting the mixing in a combustion chamber with a turbulence model and estimating the wall heat transfer in a pipe with a Reynolds-averaged model.
Study "Potential flow" first (topic 81 of 105 in Thermodynamics & Fluids). It covers the groundwork this topic builds on.
Reynolds stresses. Wall functions. y+ mesh requirements.
RANS is the industrial standard for aerodynamics and HVAC.
The next topic is "Computational fluid dynamics", which builds directly on this one.
It is classed as Advanced in Thermodynamics & Fluids (topic 82 of 105). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Thermodynamics & Fluids.
Want to practise? Open the interactive course for quick checks, quizzes, simulations and progress tracking.