Finite panel method for the simulation of wind-driven rain

In present numerical methods for the wind-driven rain (WDR) simulation, a large computational work for raindrop trajectories is required to obtain the distribution of the catch ratio because of the randomness of the initial conditions of the raindrops. A new method named Finite Panel Method (FPM) that is employed to acquire the catch ratio distribution is proposed to reduce the calculation amount and diminishes the randomness. In the FPM, raindrops ending in the corners of the panels which are divided on the surface are simulated, and then the distribution of catch ratio is acquired by a reconstruction method. As a demonstration, catch ratio results by FPM in typical flow fields are presented, including the case of the three-dimensional flow field of power-law velocity profile, and cases of the flow around two- and three-dimensional low-rise buildings. The FPM results are compared with these calculated by the classical method and literature. The results indicate that FPM can reduce the calculation amount of raindrop trajectories with equivalent accuracy compared to the classical method.