The downwardflow of a paint or powder that is applied too heavy or onto a hot surface.
油漆或粉末喷涂太厚或喷在预热的表面，从而使涂膜往下往下流动。
2
This creates downward air currents. These downdrafts hit the surface of the planet, flow outward, and collide with each other, forming updrafts.
气流向下落在地球表面，向外流动，相互碰撞，如此一来就形成上升气流。
3
In a typical software system, function calls flowdownward from higher-level components to lower-level ones; whereas events percolate up in the opposite direction. Figure 1 illustrates this pattern.