方腔流的串行程序。按照GUO论文上的非平衡态外推格式：附近一个格点，得边界三个方向上分布函数。边界也碰撞。角点处理。结果好。 -Cavity flow serial procedures. According to GUO study on non-equilibrium extrapolation scheme: near a lattice point, the boundary of three direction distribution function. The boundary