Marangoni Flows in a Bilayer Liquid Microfilm Interface on Wave-Contoured Hot Substrates

Area of Science:

• Fluid dynamics
• Heat transfer
• Interfacial phenomena

Background:

• Thermal Marangoni hydrodynamics are critical in thin-film systems with temperature gradients.
• Applications include microelectromechanical systems (MEMS/NEMS) and biological cell sorting.
• Patterned surfaces induce temperature gradients, driving interfacial flows.

Purpose of the Study:

• To analyze thermal Marangoni hydrodynamics in an immiscible, binary-liquid thin-film system.
• To investigate the influence of relative thermal conductivity (k), film thickness ratio (r), and Biot number (Bi) on flow dynamics.
• To derive approximate analytical solutions for thermal and hydrodynamic transport.

Main Methods:

• Solving coupled Navier-Stokes and energy equations using the perturbation technique.
• Analyzing the parametric influence of k, r, and Bi.
• Investigating interfacial tension fluctuations due to substrate topology.

Main Results:

• Marangoni flow strength decreases with increasing relative thermal conductivity (k).
• The effect of film thickness ratio (r) on Marangoni flow is dependent on k.
• Higher Biot numbers (Bi) weaken Marangoni flow by reducing interfacial temperature fluctuations.

Conclusions:

• The study provides insights into controlling Marangoni hydrodynamics in patterned thin-film systems.
• Findings are relevant for optimizing liquid film coatings and microfluidic devices.
• Understanding parameter influence is key for designing advanced applications.