Study on the influence of porous material on underwater vehicle's hydrodynamic characteristics

As humans accelerate the pace of marine development, autonomous underwater vehicles (AUVs) are increasingly attracting worldwide attention. Due to the limitations of carrying energy and battery technology, AUV's endurance is nonideal. Therefore, designers usually make AUVs more streamlined to reduce drag. Here we show that when a layer of porous material is attached to an AUV's surface, the AUV's drag changes significantly. In this paper, simulations of the basic body of a REMUS100 and SUBOFF submarine model were carried out under multiple conditions. It is found that the drag increases as the porous viscosity coefficient or the thickness of the porous material increases. When REMUS100 and SUBOFF models are attached to the porous material with suitable porous viscosity coefficient, their drag becomes smaller. Boundary layer theory is also used to explain and analyze the phenomenon of the proportional increase of viscous pressure drag when using porous material, which is verified by vertical plate numerical simulations. Finally, we tested the mechanical properties of porous nickel and aluminum alloy 6061, and found that the porous material does have an effect of drag reduction, and can reduce the fluctuation range of the drag during the movement.