Physicists at the University of Bayreuth have investigated the so-called Basset–Boussinesq history force acting on particles in fluids. Due to the difficulty of calculating it, this force is often neglected—a fact that Bayreuth doctoral researcher Frederik Gareis already identified as a secondary school pupil during a student research project with his supervisor. The researchers report their new findings on the history force in Physical Review Fluids.
When particles move in liquids or air with velocities that change over time, several forces act on them, including the often overlooked history force. It arises from the formation of vortices around accelerating particles in fluids. In this way, the surrounding fluid “remembers” previous particle motions and influences their subsequent movement.
“The history force is often ignored because it is mathematically complex and makes calculations significantly more demanding. It is frequently unclear whether neglecting it leads to larger errors in modeling particle motion in fluids,” says Frederik Gareis, a doctoral researcher at the Theoretical Physics I research group at the University of Bayreuth and first author of the study.
