.
We present a novel computer simulator designed to efficiently predict the velocity performance of sailing yachts. The simulator employs a state-of-the-art computational fluid dynamics (CFD) technique known as the lattice Boltzmann method (LBM) to analyze the yacht’s interactions with water and air, predicting its performance under various wind and sea conditions. Unlike traditional CFD software, which attempt to numerically solve the incompressible Navier-Stokes equations for macroscopic fluid velocity and pressure, LBM simulates fluid dynamics using a microscopic model with mesoscopic equations. The microscopic model consists of particles that stream and collide on a Cartesian lattice with discrete velocities. The mesoscopic equation, the discrete Boltzmann equation, tracks the statistical distribution of these particles’ velocities over time. Macroscopic fluid characteristics, such as density, velocity, and kinetic energy, are quantified by taking moments of the velocity distribution function. Aerodynamic forces exerted by wind on the sailing yacht are evaluated using the momentum exchange method (MEM), which sums the momentum changes of all particles colliding with the yacht’s boundary. The net force calculated by MEM provides the driving force on the yacht. LBM conserves mass both locally and globally. Its algorithm and data structure are highly compatible with GPUs, resulting in significant speedups compared to CPU run-times, often by several orders of magnitude. This allows our numerical simulator to capture complex flow dynamics such as large unsteadiness, vortex shedding, flow detachment and reattachment, as well as transitional flows in a similar manner to direct numerical simulations, but more efficiently.
