Total magnetic force on a ferrofluid droplet in microgravity

• Published in: Experimental thermal and fluid science Vol. 117; p. 110124
• Main Authors: Romero-Calvo, Álvaro, Cano-Gómez, Gabriel, Hermans, Tim H.J., Parrilla Benítez, Lidia, Herrada Gutiérrez, Miguel Ángel, Castro-Hernández, Elena
• Format: Journal Article
• Language: English
• Published: Philadelphia Elsevier Inc 01.09.2020; Elsevier Science Ltd
• Subjects: Droplets; Ferrofluids; Magnetic fields; Magnetic mass transfer; Magnetism; Microgravity; Numerical prediction; Space engineering; Total magnetic force; Magnetic mass transfer; Space engineering; Total magnetic force; Ferrofluids; Microgravity
• ISSN: 0894-1777; 1879-2286
• DOI: 10.1016/j.expthermflusci.2020.110124

•The total magnetic force exerted on ferrofluids plays a major role in microgravity.•Common on-ground simplifying assumptions may lead to significant errors in low gravity environments.•Equivalent formulations are affected differently by modeling assumptions.•This is exemplified with observations of a free-floating ferrofluid droplet in microgravity. The formulation of the total force exerted by magnetic fields on ferrofluids has historically been a subject of intense debate and controversy. Although the theoretical foundations of this problem can now be considered to be well established, significant confusion still remains regarding the implementation of the associated expressions. However, the development of future applications in low-gravity environments is highly dependent on the correct modeling of this force. This paper presents a contextualized analysis of different proposed calculation procedures and validation in a space-like environment. Kinematic measurements of the movement of a ferrofluid droplet subjected to an inhomogeneous magnetic field in microgravity are compared with numerical predictions from a simplified physical model. Theoretical results are consistent with the assumptions of the model and show an excellent agreement with the experiment. The Kelvin force predictions are included in the discussion to exemplify how an incomplete modeling of the magnetic force leads to significant errors in the absence of gravity.