2. This modification of the direction is referred to as
perturbing the surface normals and is the basis of bump mapping.
方向的修改是参考去当作一个搅动的表面法线和基本的凹凸贴图。
3. At time t=t0, the setting of the blades is changed suddenly such that they assume the position denoted by the solid blades,
perturbing the mass flow in a one-dimensional sense.
当t=t0时,叶栅的位置突然改变,因此取代实心叶片所标示的位置,在一维的意义上干扰了质量流动。