Food for thought: (1) turbulence is natural to the Navier-Stokes equations, not to models. Let's make an example: let's solve a turbulent channel flow for Re_tau = 171, and use a grid suitable for LES (196x128x96, 4pi x 2pi x 2). We will use PISO (assume, for now is energy-conserving) and 2order CDS, and the time scale is such that Co < 1. I run 3 cases: no Model, LES model, and a RAS model. Where will I get "turbulence"? More precisely, If I sample a point far from the wall, Will I get an Enegry spectrum (forget whether its slope is correct) in either case?