GALCIT Colloquium

Part 1

The "law of the wake" for the outer layer of canonical wall-bounded turbulence is revisited, using reference data of channel flow DNS at Ret = 5200. Our focus is thus on the "wake function" F(Y) with Y=y/h: the excess profile one adds to the logarithmic profile to obtain Coles composite profile. For that, the function Q(Y) = Y F'(Y) from the DNS is examined in details. We propose a simple model for Q(Y), which cover the full range up to Y = 1. Its analytical integration then provides a simple and complete model for F(Y), which is seen to recover well the DNS data. The model is then further tested on a ZPG boundary layer: here too, the obtained F(Y) model is seen to recover well the DNS data.

Part 2

An immersed lifting (and recently also dragging) line model has been developed to efficiently simulate, using the vorticity-velocity formulation, incompressible flows involving slender wings and/or blades and turbulent wakes: our "vortex particle-mesh" (VPM) code. An actuator line method has also been implemented in our 4rth-order staggered-mesh velocity-pressure code; which also allows for realistic atmospheric boundary layer simulations. A few examples of applications involving LES of complex wakes and interactions (also with the ground) will be presented concerning wings, rotorcraft, and wind turbines.