Multi-scale turbulence modeling and the maximum information principle

We discuss averaged turbulence modeling of multi-scales of length for an incompressible Newtonian fluid, with the help of the maximum information principle. We suppose that there exists a function basis to decompose the turbulent fluctuations in a flow of our concern into the components associated with various spatial scales and that there is a probability density function f of these fluctuation components. The unbiased form for f is determined and the turbulence model is closed, with the multi-scale correlations up to the fourth order, through maximizing the information under the constraints for that flow. Due to the computational difficulty to maximize the information, a closely related but simple alternative objective is sought, like the determinant or the trace of the second order correlations of the turbulent flow. The issues still yet to be resolved are indicated.