SFS2 off-bow airwakes: Effects of Reynolds number and atmospheric boundary layers

Abstract

The present work is concerned with identifying effects of Reynolds number and time-varying full-scale atmospheric boundary layers on the characteristics of the SFS2 ship airwake for a 0 deg headwind and -15 deg, -30 deg, and -60 deg off-bow winds using large eddy simulation. Reynolds number effects between a 1:50-scale wind tunnel model (Re1/50 = 2.9x106) and full-scale ship (ReL = 160x106) are investigated for a non-atmospheric boundary-layer inflow at 0 deg, -15 deg, -30 deg, and -60 deg wind angle. Atmospheric boundary-layer effects are studied for atmospheric boundary layers with two distinct levels of shear for a 0 deg headwind and -60 deg off-bow wind. Overall, headwind airwakes demonstrate Reynolds independence and full-scale atmospheric boundary-layer independence on the mean velocity profile sampled at multiple locations above the SFS2 flight deck, but notable changes in energy content and turbulence intensity both inside the airwake and in the freestream when full-scale atmospheric boundary-layer effects are simulated. The statistical quantities and flow field characteristics of off-bow airwakes are more sensitive to both significant changes in Reynolds number and inclusion of full-scale atmospheric boundary-layer effects.