How much raindrop energy is used for transportation of the two-phase splashed material?

Abstract

The ejection of a mixture of solid (soil) and liquid (water) phases is one of the aspects of the energy dissipation of the impacting drop during the soil splash phenomenon. All calculations to date have only been taking into account the ejection of solid phase material and were based on significant simplifications of the measured quantities. Therefore, the aim of the study was an improved calculation of the falling drop energy transferred to the ejected material, while considering that such material was a mixture of solid soil particles and water droplets and therefore, “two-phase”. Experimental variants included combinations of soils with different textures and initial moisture contents as well as various falling water-drop energies. Two complementary methods of i)splash cup measurements and ii) image analysis based on high-speed cameras were used for the calculation of quantities i.e. the number of ejected particles, their mass, and their ejection velocity. Based on the obtained results, it was stated that the kinetic energy of ejected particles, expressed as a percentage of falling drop energy, ranged from 1 % to 14 %. This percentage depended strongly on soil texture as well as initial moisture content. The highest values were obtained for soil with the largest amount of sand fraction and the lowest for the soil with the largest amount of finer fractions. All tested soils showed a trend of a higher drop energy transferred to the splashed particles with increasing initial soil moisture content. Taking into account the varied energy of the falling drop variants, the amount of energy transferred to ejected particles was constant.