Abstract

This paper presents analytical and computational fluid dynamics (CFD) investigations of the applicability of a novel ferrofluidic magnetic micropump for fluids with stress-sensitive microparticles. The velocity, pressure, and stress fields in the annular channel of the pump were determined analytically for the case of channels with rectangular cross sections and small aspect ratios (h/w→ 0) under the assumption of laminar incompressible Newtonian flow conditions. CFD simulations were used to produce flow field solutions for the full range of h/w, and to verify the derived analytical expressions. Analytical results show that the velocity and stress fields at a certain radial position in the channel follow that of a Poiseuelle type plug flow scaled by the channel’s width ratio over the radial position ratio. A particle damage index (PDI) following the definition of the index of hemolysis (IH) in medical blood pumping was introduced in this work and expressed in terms of pump geometry, plug speed, and working fluid viscosity. Analytical results show that a model ferrofluidic blood pump with a channel width of 100 µm, channel height of 250 µm, and mean radius of 500 µm, can in theory deliver up to 37.5 µl/s of blood without exceeding the threshold design objective PDI of blood pumps.

Key words: Ferrofluidic magnetic micropump, stress-sensitive microparticles, particle damage index, biomedical applications of micropumps.