基于PBD框架的流体模拟

The Fluid Simulation Based on PBD Framework

在对现实流体进行动画模拟时,传统的解决办法是使用SPH方法,对一般场景的模拟,SPH方法能很好地解决问题,且模拟效果能达到预期的效果;但对实时性、交互性高的场景,SPH方法具有一定的局限性,在模拟的过程中易出现不稳定,基于位置的PBD方法能很好的解决SPH所出现的不稳定性。在PBD框架下,通过迭代求解每个粒子的约束方程,通过粒子间的约束来使其接近于常量密度,同时在SPH方法的基础上实现流体粒子的不可压缩性,继承SPH易于实现的优点,解决了SPH在实时模拟时所出现的不稳定性问题。其主要优势如下:1.模拟更加稳定;2.允许更大的时间步长;3.能在更小的核半径下实现流体的模拟。

While simulating realistic fluids, the traditional solution is to use the SPH method to simulate the general scenario. The SPH method can solve the problem well and the simulation effect can achieve the expected effect. However, the SPH method has some limitations in real-time and interactive scenarios. It is easy to appear instability in the process of simulation. The position based PBD method can solve the in- stability of SPH well. In the framework of PBD, the constraint equations of each particle are iteratively solved and the particle density is ap- proximated by the constraint between particles. At the same time, the incompressibility of the fluid particles is achieved based on the SPH method, which is inherited from the SPH easy to implement advantages, to solve the SPH in real-time simulation of the instability prob-lems. The main advantages are as follows： 1. Simulation is more stable. 2. Allow larger time steps. 3. Can simulate the fluid at a smaller nu-clear radius.