Electrokinetics of polymeric fluids in narrow rectangular confinements

Area of Science:

• Fluid Mechanics
• Rheology
• Electrokinetics

Background:

• Previous studies often use idealized parallel plate channels, unlike the rectangular ducts common in experiments.
• Understanding complex fluid behavior in realistic geometries is crucial for device applications.

Purpose of the Study:

• To analyze electroosmotic and pressure-driven flows of polymeric liquids in rectangular confinements.
• To investigate the influence of viscoelasticity and electrical double layers on flow dynamics and streaming potential.

Main Methods:

• Utilized two non-linear viscoelastic models: simplified exponential Phan-Thien-Tanner (sePTT) and Giesekus.
• Analyzed combined electroosmotic and pressure-driven flows, and streaming potential from mechanically driven flow.
• Investigated the impact of channel aspect ratio and electric field strength.

Main Results:

• Electric fields strongly increase flow rate with field strength and fluid viscoelasticity.
• Viscoelasticity and shear thinning significantly enhance streaming potential compared to Newtonian fluids.
• Channel aspect ratio has a greater influence on throughput and streaming potential for highly viscoelastic fluids.

Conclusions:

• Polymeric liquid flow in rectangular channels is highly sensitive to electric fields and viscoelastic properties.
• Viscoelasticity amplifies streaming potential and throughput, especially in channels with specific aspect ratios.
• Secondary flows observed in Giesekus fluids are influenced by electric field strength in combined flow scenarios.