A study of laminar flow of polar liquids through circular microtubes

Abstract

Recently, the validity of using classical flow theory to describe the laminar flow of polar liquids and electrolytic solutions through microtubes has been questioned for tube diameters as large as 500 m ͓Brutin and Tadrist, Phys. Fluids 15, 653 ͑2003͔͒. This potential increase in flow resistance, which has been attributed to electrokinetic effects and enhanced surface roughness effects, is critical to the understanding of certain biofluid systems. We seek to characterize this phenomenon for a variety of capillary/liquid systems. Using a numerical solution to the Poisson-Boltzmann equation, we have calculated the electroviscous effect for the systems under consideration. We have also measured the pressure drop as a function of flow rate across well-characterized stainless steel and polyimide microtubes ranging in diameter from 120 m to 440 m. Deionized water, tap water, a saline solution, and a variety of glycerol/water mixtures were used. The calculations and measurements suggest that any deviation from Poiseuille flow for tubes larger than 50 microns in diameter is more likely caused by the enhanced importance of surface roughness in microtubes than by electrokinetic effects.

Reexamination of Hagen-Poiseuille flow: Shape dependence of the hydraulic resistance in microchannels

“…We note that in micro-channels the flow properties and electrokinetic phenomena may be somewhat connected and substantial deviations from classical Poiseuille flow have been reported recently, see Ref. 7 and references therein. Nevertheless, our observation is an important first step with relevance to the use of micro-fluidic channels in lab-ona-chip applications.…”

Experimental study of compressibility, roughness and rarefaction influences on microchannel flow

“…Phares and Smedley [17] studied water, saline, and glycerol/water mixture in circular tubes. The relative surface roughness for four stainless steel tubes with D = 164-440 lm ranged from 2.5% to 1.8% and the relative surface roughness for two polyimide tubes with D = 119 and 152 lm was less than 1%.…”

MEMS-based fabrication and microfluidic analysis of three-dimensional perfusion systems

“…However, simple liquid flows are properly described by continuum hydrodynamics with non-slip boundary conditions satisfied on the walls (Ho and Tai 1998). The majority of microflow studies supports the classical flow theory (Sharp et al 2001;Sharp and Adrian 2004;Baviere et al 2005;Phares and Smedley 2004). Thus, in the following analysis we adopt the friction factor from the classical theory for a fully developed laminar flow in round capillaries by the use of Darcy's formula f=64/Re, where Re is the Reynolds number.…”