Rainfall simulator

The evolution of the rainfall simulator started in the late 1800s when German Scientist Ewald Wollny formally studied erosion.

In the 1930s, pioneers of erosion studies tightened control of their experiments by building the first rainfall simulators,[1] ‌[2] ordinary sprinkle cans or pipes with holes.

[3] As the technology matured in the early 1990s, rainfall simulators were used in the United States as part of the Water Erosion Prediction Project to update the universal soil loss equation.

[4] Modern research simulators are typically designed around the tasks they are intended to perform, ranging from simple demonstrations for farmers to the advanced scientific study of erosion, surface runoff, and sediment size.

The first type is a gravity-fed unpressurized feed system such as a perforated pipe, hanging yarns, or an array of syringe needles which form drops.

Drop generator height is important in many scientific simulators to ensure water droplets approach terminal velocity in the downward direction.