Huge reduction in pressure drop of water, glycerol/water mixture, and aqueous solution of polyethylene oxide in high speed flows through micro-orifices

Abstract

Microfluid mechanics is one of the most exciting research areas in modern fluid mechanics and fluid engineering because of its many potential industrial and biological applications. In the present study, pressure drops ͑PDs͒ were measured for water, a 50/50 glycerol/water mixture, and a 0.1% aqueous solution of polyethylene oxide ͑PEO͒ 8000 flowing at high velocities through various sizes of micro-orifice. It was found that the measured PD of water and the glycerol/water mixture agrees with the prediction of the Navier-Stokes equation for orifices 100 and 400 m in diameter, but it is lower for orifices less than 50 m in diameter. In particular, the measured maximum PD was almost two orders of magnitude lower than the prediction for the 10 and 5 m diameter orifices. The glycerol/water mixture, possessing a viscosity ten times higher than water, provided nearly the same PDs as water when the reduction was generated. The solution of PEO produced a lower PD than water and the glycerol/water mixture except for the 400 m diameter orifice. Several factors, including orifice shape, deformation of orifice foil, wall slip, transition, cavitation, and elasticity were considered but the evidence suggests that the reduction in PD may be caused by wall slip or the elasticity induced in a flow of high elongational rate.

Drag reduction for liquid flow through micro-apertures

“…Silicone oils, polyethylene glycol aqueous solutions, and surfactant aqueous solutions were used in the experiment: the kinematic viscosity of the two kinds of silicone oils was 10 −6 m 2 /s and 10 −5 m 2 /s, and they were similar to those of water and the 50/50 glycerol-water mixture used in the previous paper [9], respectively. A 10 3 ppm aqueous solution of polyethylene glycol 20000 (PEG20000; 20000 indicates the molecular weight (MW)) was used for the purpose of comparison with PEG8000, which had been a test fluid in the previous paper [9].…”

“…Moreover, the flow field of a blood capillary [7] and the kidney [8] in living bodies is in a range of microfluid mechanics. In a previous paper [9], the present authors measured pressure drops (PD) for water, a 50/50 glycerol/water mixture and a 10 3 ppm (0.1%) aqueous solution of polyethylene glycol (PEG) 8000 flowing at relatively high velocities through various sizes of micro-orifices. The * Corresponding author.…”

Flow Properties of Microbubble/Polyethylene Glycol Mixtures Passing through Orifices and Slits

“…14) In this numerical scheme the velocity and pressure are coupled by the SIMPLE method and are expressed on a staggered grid in a two-dimensional cylindrical coordinate system. The grid number is 1024 in each direction.…”

“…[9][10][11][12][13][14][15] Figure 3 shows the experimental apparatus for measuring pressure drops. The basic setup is the same as that in previous research.…”

“…The basic setup is the same as that in previous research. [9][10][11][12][13][14][15] up to 500 Pa, 10 kPa, and 500 kPa.…”