基于随体坐标系的水下机器人水动力数值计算方法

Numerical calculation methods for hydrodynamics of unmanned underwater vehicles based on body-fixed coordinate frames

针对水下机器人水动力数值计算问题,提出了基于静态网格的随体坐标系附加动量源计算方法.首先推导了N-S方程在随体坐标系中的表达式,从理论上证明了采用附加动量源方法可以实现对水下机器人各种定常、非定常运动进行基于静态网格的水动力数值计算,通过对SUBOFF标准潜艇模型以及4500米级AUV进行黏性类水动力计算并与试验结果进行比对,验证了该计算方法在黏性类水动力计算中的可行性.通过对椭球体进行惯性类水动力(附加质量)计算并与理论值进行比对,验证了该方法在惯性类水动力计算中的可行性.本文所提方法可避免采用动网格、重叠网格模拟非定常运动带来的耗时较长、收敛性不佳等问题.

For the problem of numerical calculation hydrodynamics of unmanned underwater vehicles(UUVs), this paper presents a method based on static meshes and added momentum sources in a body-fixed coordinate frame. First, by deriving the N-S equations in a body-fixed frame, it is proved that added momentum methods can be used to simulate steady motion and unsteady motion of UUVs on the basis of static meshes. To validate the feasibility of the method for viscous hydrodynamics calculation, the SUBOFF standard submarine model and a 4500 m AUV model are used and compared with tank test results. And, to validate the feasibility of the method for inertial hydrodynamics calculation, the added masses of an ellipsoid are computed and compared with theorical values. The comparison showes that the proposed method can meet the hydrodynamic force computing well, and the method can avoid those problems such as long time comsuming, bad convergency, which usually caused by dynamic mesh methods or overset mesh methods.