Water Drop Kinetic Energy and Momentum Measurement Considerations

Abstract

The impulse applied to a surface from water drop impact can be measured experimentally by recording and integrating impact force over time. A momentum number, defined as measured impulse divided by the drop's momentum, is a dimensionless physically-based parameter which can be used for modeling soil movement due to water drop impact. Impact forces were measured and integrated over time and the momentum number equals one for a smooth-dry surface and is greater than one for a smooth-wet or a rough surface. Accurate impulse measurements do not require sensors with fast dynamic response or calibration, but reasonant frequencies must be sufficient to minimize signal amplification. The factors to be considered when measuring impulse or work from water drop impact are identified.