Flow Analyses around Downwind-Sail System of an IACC Sailing Boat by a Multi-Block NS/RaNS Method

The present study concerns analyses of flows around downwind-sail system of an International America's Cup Class (IACC) sailing boat. The numerical method is a multi-block Navier-Stokes and Reynolds-averaged Navier-Stokes equation solver (hereafter, referred to as multi-block NS/RaNS method) recently developed by the present author. The main objectives of the present work are two folds: (1) an initial capability evaluation of the present multi-block NS/RaNS method in analyses of large-scale-separation flow; and (2) application of the present method to flow analyses around downwind-sail system of IACC sailing boat, on which very few studies have been so far reported. In the present study, the mainsail/spinnaker configuration is particularly considered, where focuses are placed on the aerodynamic interactions between the mainsail and spinnaker as well as the influences of sail trimming on flow and aerodynamic forces. The present numerical method is based on an extension of the RaNS method for ship flow analyses for applications to more general fluid dynamic problems, which was successfully demonstrated through the present work.