If some form of friction is present in the disk material, it tries to slow down the more rapidly orbiting inner regions and speed up the more slowly orbiting outer regions.

• 假如圆盘物质间存在某种形式的摩擦力，会使得原来以较快速度运行的内侧区域速度减慢，并使原本移动较缓慢的外侧区域速度提高。