Particle movement subject to a fluctuating fluid force

Article By:

Diplas, Panayiotis Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia.

Dancey, Clinton L. Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia.

Last reviewed:2014

DOI:https://doi.org/10.1036/1097-8542.YB140256

The movement of particles from an erodible surface by a flowing fluid is a fundamental physical phenomenon that occurs in many industrial processes and is applicable to biological flows and a wide range of natural phenomena. The erosion and transport of sediment caused by the flow-boundary interaction is a central problem in Earth surface dynamics, where the global amount of sediment eroded annually over the continental surface of the Earth is estimated to be between 80 and 100 billion metric tons. Approximately 20 billion metric tons make it all the way to the ocean, with the rest deposited in reservoirs, lakes, rivers and their floodplains, and wetlands. Additionally, the smaller grains are carriers of various chemicals and pollutants. Human activities, such as deforestation and the increase of impervious surfaces, as well as climate change, tend to exacerbate erosional problems through the redistribution of rainfall in terms of surface and subsurface runoff and enhancement in the frequency of extreme meteorological events. In October 2012, Hurricane Sandy provided a vivid and very painful demonstration of the power that such extreme events possess and the massive and catastrophic erosion damage that they can cause. The effects of the rearrangement of the eroded material over the surface of the Earth is not at all well understood, nor is the mechanism that initiates the process—the dislodgement of a sediment grain from an erodible boundary. Fundamentally, the physical mechanism for particle motion must be related to an unbalanced force on the particle and the application of Newton's laws of motion.

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