从推移质运动的爱因斯坦假设出发,得到推移质扩散的主方程、Fokker-Planck方程和Langevin方程.从水流阻力、水流脉动的功率普和床面的分形粗糙性等方面指出了爱因斯坦假设存在的问题,引入FBM和FLM描述推移质运动,得到颗粒单步运动步长的分形列维稳定分布.应用胡春宏、陈家扬等人的水槽试验数据对理论进行了验证,理论分析结果和实验结果基本吻合.
The Master equation,Fokker-Planck equation and Langevin equation for the diffusion of bed load are obtained through Einstein's hypotheses about bed motion.The problems in Einstein's hypotheses are pointed out from the viewpoints of flow resistance,spectrum of fluid fluctuation and fractal coarseness of bed surface.Further more,the fractional Brownian motion and the fractal Levy stable motion are introduced to describe the motion of bed load.As a result,the fractal Levy stable distribution of the step length of bed load grain's single step motion is acquired,which is verified theoretically by Hu Chun-hong and Chen Jia-yang's experimental data.