Hy dear Friends,

Why you need to use turbulence modeling?

Cheers. Valdemir

Valdemir,

Turbulence modelling is a method to handle some aspect of reality, that cannot yet be handled by a digital computer, with a digital computer. You need to use turbulence modelling in the present understanding because current science is not able to find a reasonable method for handling turbulent flows. All they can do is to state some arbitrary, difficult to understand model that has a number of numbers that must be adjusted by hand to your problem so that the model does not calculate complete nonsense.

I am sure there are methods to properly handle turbulent flows, but they still have to be discovered. I am in doubt if this generation of turbulence researchers will do the job, as they have a paradigm that is still pre-modern.

regards

Ok, Tom.

Your comments are very important and consistent. But, and the intantaneous Navier Stokes Equations? is not the method that you are looking for?

Cheers

The problem is that we do not have the computational horsepower to fully model the Navier-Stokes equations at the level of refinement needed to truly simulate turbulent flow for general problems. What you are referring to is termed "direct numerical simulation" or DNS, and works for a small set of simplified geometries and flows. But to use DNS to compute flow around an F15 fighter aircraft would require billions of grid points, and we don't have the computer resources to handle that today. Hence we resort to turbulence modeling.