Abstract

With the electrification of power, the enhancement of safety equipment, and the sophistication of automatic driving systems, many electrical components such as sensors, radars, and cameras have been installed in automobiles in recent years. It is necessary to take waterproof measures for these electrical components and to take measures to prevent wetness by water as much as possible. For underbody, which requires strength, anti-corrosion coating measures are required to prevent damage caused by water exposure containing chemical substances such as anti-freezing agents. Therefore, the manufacturing cost for the protection from water splashing is not so small. One of the ways to reduce the cost of the damage countermeasures is to reduce the amount of water that hits the lower part of the vehicle body. For this purpose, it is considered that the reduction of the water splashing caused by the tires is effective. In this paper, we applied a shape optimization method based on numerical simulation and tried to minimize the amount of water being splashed on the underbody by optimizing the tread pattern shape of the tire. In simulating such problems, it is necessary to model the water splashing caused by tire rotation from the road surface to the vehicle body surface. As a numerical computation method that can efficiently track the separation, collision, and coalescence of many water droplets in a wide space, the computation method based on the particle method is considered more suitable than the mesh-based conventional CFD computation. Besides, using the mesh-free particle method has the advantage that the remeshing does not be required when changing the shape of the flow path. Therefore, in this paper, we adopted Particleworks, a CFD software that uses MPS (Moving Particle Simulation), which is one of the major particle methods, for numerical simulation. In addition, CAD-based parametric shape optimization software CAESES was used to optimize the shape of complex tread patterns, and by efficiently repeating the optimization computation cycle, the optimum shape could be obtained in a short time.