Alternating Current Electroosmotic Flow of Maxwell Fluid in a Parallel Plate Microchannel with Sinusoidal Roughness.

Area of Science:

• Fluid Dynamics
• Microfluidics
• Rheology

Background:

• Electroosmotic flow (EOF) is crucial in microfluidic devices.
• Understanding fluid behavior in microchannels with surface roughness is essential for device design.
• Viscoelastic fluid properties can significantly alter flow dynamics compared to Newtonian fluids.

Purpose of the Study:

• To analyze the AC EOF of a viscoelastic Maxwell fluid in a parallel plate microchannel with sinusoidal roughness.
• To investigate the influence of wall roughness and fluid viscoelasticity on flow characteristics.
• To determine the impact of key parameters like oscillation Reynolds number and Deborah number on velocity profiles and phase lags.

Main Methods:

• Application of the Debye-Hückel approximation.
• Utilizing boundary perturbation expansion and separation of variables techniques.
• Derivation of perturbation solutions for potential distribution, velocity, and mean velocity.

Main Results:

• Significant differences observed in velocity amplitudes between Newtonian and Maxwell fluids.
• Wall roughness introduces velocity fluctuations and strongly influences the velocity distribution of viscoelastic fluids.
• Velocity is highly dependent on the phase difference of roughness between the plates; increasing oscillation Reynolds number and Deborah number leads to more oscillations but decreased velocity amplitude.

Conclusions:

• Surface roughness in microchannels significantly impacts AC EOF of viscoelastic fluids.
• The interplay between roughness, viscoelasticity, and applied fields dictates complex flow behaviors.
• Phase lag is sensitive to roughness parameters and fluid properties, diminishing at higher characteristic length ratios.