几何约束的改进弹性体网格变形方法研究及应用

Research and application of improved elasticity-based mesh deformation method based on geometry constraints

针对现有弹性体网格变形方法无法有效抑制网格单元出现"负体积"和过度畸变等问题,引入体积弹性模量约束和挤压弹性模量约束,提出一种基于几何约束的改进弹性体法。借助Patrick网格质量参数,选取三维长方体边界在旋转、平移和伸展变形三种方式下的大幅度运动,对比研究引入几何约束后的改进效果。仿真计算二维NACA0012翼型的俯仰振荡和三维伸缩翼变形过程的气动特性,结果表明:基于几何约束的改进弹性体法显著提高了变形网格的鲁棒性,尤其在大变形时能够有效约束较差网格单元,改善经典方法存在的问题,可为非定常流场问题的求解提供有力支撑。

Aimed at the problem that the current elasticity-based mesh deformation method always cannot control some poor elements suffering"negative volume"and extreme distortion,the volume and the extruding constraints on modulus of elasticity were introduced to solve above shortages and a modified elasticity-based method based on these geometry constraints was presented. Combined with Patrick mesh quality measure,the differences between the modified method and the classical method were fully analyzed by testing a 3D cubic model with three types of motion or deformation in wide-range,such as rotation,translation,and stretch. The modified method was applied to simulate the plunging motion of NACA0012 airfoil and stretching deformation of wing. Results show this modified method can improve the robustness of elasticity-based method by constraining poor elements in wide-range of motion or deformation,thus providing a better support for solving the unsteady flow problems.