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In the development of a rainfall simulator for soil erosion research, two of the prime criteria which have been used over the years to evaluate performance have been that the simulated drop size distribution should be similar to that of natural rainfall, and that the drop impact velocities should approximate the terminal velocities of natural raindrops (Bubenzer 1979). Satisfying these criteria insures that the energy and momentum characteristics of the simulated raindrops closely approximate those of natural rainfall. Rainfall energy has been demonstrated to be a significant factor in the determination of soil erosion (Bubenzer 1979). Laws (1941) and Laws and Parsons (1943) developed a number of relation ships for naturally occurring raindrops, including mean drop diameter and mean fall velocity versus rainfall intensity, drop size distribution versus intensity, and fall velocity versus drop diameter. These relationships have been used as a set of basic standards for the comparison of results from rainfall simulators (Bubenzer 1979).
an approach for characterizing falling water droplets
Beals, D., Dickerson, W. T., Helsdon, D. S. and R. Pall 1983. AN APPROACH FOR CHARACTERIZING FALLING WATER DROPLETS. Canadian Agricultural Engineering 25(2):189-192.
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