An example of computational approach used for aerodynamic design of a raindisdrometer

The present work reports on the application of a computational fluid dynami cs-based method as a tool to improve the aerodynamic design of rainfall mea surement devices. The focus is on anew instrument, a two-dimensional video disdrometer that provides information about raindrop size distribution. The distorted wind field around and inside the instrument's body is simulated using a three-dimensional numerical model. A modified geometry of the instr ument, suggested for operational purposes, is tested numerically. Trajector ies of raindrops are simulated to investigate the wind effect on the catchm ent efficiency of the instrument. A stochastic Lagrangian particle-tracking model that accounts for the turbulence effect is examined. General guideli nes related to aerodynamic aspects of the design of in-situ rainfall measur ing devices are discussed.