Validation of an Experimental Setup to Study the Behaviour of a Free-Falling Particle in Viscous Fluid

Abstract

A sphere falling in a fluid under the influence of gravity will accelerate until the buoyancy and drag forces balanced the gravitational force. During this steady-state, the falling velocity become constant and known as the terminal velocity. The purpose of this work is to describe the experimental setup aimed at studying the behaviour of free-falling particle in incompressible viscous fluid. The terminal velocity of a free falling sphere in incompressible fluid was captured experimentally and validated using analytical empirical model. The preset investigation is a preliminary study designed to validate the reliability of the built experimental rig. The experimental work is done by undertaking experiments in water with free-falling stainless steel spheres of different diameters, varying between 4 mm and 7 mm. The spheres are released just above the water free surface at the centre of the column and recorded by a high speed camera. The results from the experiments agreed well with theoretical solution. Therefore, the reliability of the build experimental setup was proved. Hence, it can be used to conduct experiments involving more complicated particle shape and fluids.