Technical Papers and Presentations

Droplets and their interaction with solid substrates are ubiquitous in nature. Such interactions also have commercial significance, as they are observed in many important applications. Impingement dynamics of aqueous droplets with solid substrates are largely understood due to extensive investigations carried out in the past. However, droplets with special characteristics and interactions with substrates in external force fields (e.g., electric, magnetic) remain underexplored. In this regard, the present work investigates the effect of a magnetic field on the impact dynamics of a ferrofluid droplet on a heated solid substrate. Ferrofluids are colloidal liquids consisting of magnetic nanoparticles in a nonmagnetic base liquid. They exhibit magnetic characteristics which can be utilized to externally control/manipulate their flow behavior. The magnetic field induces an attractive magnetic force which alters the spreading dynamics, thus affecting the transport characteristics of such impinging droplets. The maximum spreading diameter, as well as the contact time of the droplet with the substrate, increases significantly, which leads to the enhancement in heat transfer. Such parameters can also be controlled by tuning the induced magnetic force. COMSOL Multiphysics has been used to numerically model the multiphase flow phenomena involving magnetic field, interface tracking using phase field model, fluid flow and heat transfer modules.