流体自由表面模拟的一种改进算法

An improved algorithm for fluid free surface simulation

基于光滑粒子流体动力学(smoothed particle hydrodynamics,SPH)方法的流体自由表面的模拟需要在流体自由表面附近生成空气粒子来保证模拟精度,传统方法生成的空气粒子分布不够均匀平滑,影响模拟效果,而且计算量较大。文章对传统的连续表面力(continuum surface force,CSF)模型流体自由表面模拟添加空气粒子的方法进行改进,首先在流体自由表面的法向上动态生成双层空气粒子,然后对生成的空气粒子施加切向力,使得空气粒子均匀分布,从而提高流体自由表面的模拟精度。考虑到一般模拟的时间步长很短,空气粒子的位置在单位时间步长下变化很小,可以近似认为短时间内上一时间步的空气粒子还是下一时间步的空气粒子,因此文中提出自适应间隔时间步长重新生成空气粒子的的方法,减少了计算量,提高了模拟效率。

Simulation of fluid free surface based on smoothed particle hydrodynamics(SPH) method requires generation of air particles near the fluid free surface to ensure simulation accuracy. The distribution of air particles generated by the traditional method is not uniform and smooth, which affects the simulation effect and has a large amount of calculation. In this paper, the traditional method of adding air particles to the free surface simulation of fluid in continuum surface force(CSF) model is improved. Firstly, the bilayer air particles are generated dynamically on the normal direction of the free surface of the fluid, and then the tangential force is applied to the generated air particles, so that the air particles are uniformly distributed and therefore the simulation accuracy of the free surface of the fluid is improved. Since the simulated time step is very short and the position of the air particle changes very little under the unit time step, the air particles in the previous step can be considered as the air particles in the next step in a short period of time. Based on this consideration, an adaptive interval step method is proposed to regenerate air particles, which reduces the amount of calculation and improves the efficiency of simulation.