Turbulence

Turbulence - Definition and RANS

Turbulence is generally 3D (even for a predominant 1D flow) and unsteady. It is usually difficult to solve. It can be solved only numerically and is computational intensive.

There are a range of solution procedures - depending on the resources available to solve turbulent flow

In the simplest approach:

the space and time dependence are decoupled

the Navier-Stokes equation are Reynolds (time) averaged (RANS)

suitable models are defined to handle the perturbation terms (turbulence closure)

the PDEs are solved and approximation schemes are introduced to calculate turbulent information at the wall