FWF - Drop-Part - Free drop-particle collisions in air

This project focuses on understanding how small liquid drops and solid particles interact when they collide in the air. Such collisions are common in nature; for example, raindrops may encounter insects, pollen, or any kind of dust on their trajectory. In industry, drop-particle collisions can be used to agglomerate small grains into larger granules that are easier to handle. Conversely, in processes like spray drying, which is typically employed to obtain powdered milk or coffee, such collisions must be avoided as they decrease the final product quality. Despite their importance, not much is known about these collisions. Experimentally, it is very difficult to control the trajectory of tiny drops and particles to obtain such collisions. Numerical simulations are also challenging, as very high spatial and temporal resolutions must be applied on a large system evolving during a long time period. Our project will use a new experimental method to create controlled collisions between drops and particles in the air. Particles will be produced in the air by hardening well-controlled droplets and force them to collide with different, yet well-defined, liquid droplets. Using this method, we aim to collect data that can help us predict the outcomes of these collisions, which vary depending on the size and speed of the drops and particles. We will not only look at dry and hard particles but also wet and soft ones, which are more representative of real-life situations. This research will provide a model of drop-particle collisions, which will not only advance scientific knowledge but also offer practical benefits across various industries, making processes more efficient and effective. Additionally, we will gain precious information about the efficiency of rainfall in cleaning the air we breathe.