Deformation of soap bubbles in uniform magnetic fields

Area of Science:

• Physics
• Materials Science
• Fluid Dynamics

Background:

• Sessile bubbles are commonly studied for their surface tension properties.
• Ferrofluids offer unique responses to magnetic fields, enabling novel bubble behavior.
• Understanding bubble deformation is crucial for applications in microfluidics and materials processing.

Purpose of the Study:

• To investigate the deformation of hemispherical ferrofluid soap bubbles under uniform vertical magnetic fields.
• To analyze how magnetic field amplitude, initial bubble volume, and ferrofluid volume influence bubble shape.
• To develop a model explaining the observed meniscus deformation.

Main Methods:

• Utilized Helmholtz coils to generate controlled vertical uniform magnetic fields.
• Monitored bubble deformation and shape changes using precise measurements.
• Employed a simple model to rationalize meniscus height growth.

Main Results:

• The meniscus bore the majority of the deformation, transforming into a cylindrical shape.
• The remaining bubble portion adapted as a spherical cap to the meniscus transformation.
• Meniscus height growth was modeled by the interplay of capillary, gravity, and magnetic effects.
• Two characteristic lengths, capillary and magnetic, were identified, defining two distinct deformation regimes based on magnetic field intensity.

Conclusions:

• Ferrofluid bubble deformation is governed by a balance of capillary, gravitational, and magnetic forces.
• The study identifies two distinct regimes of meniscus shape, dictated by magnetic field strength.
• The findings provide insights into the physics of magnetic fluid interfaces and their shape dynamics.