Electro-osmotic flow of couple stress fluids in a microchannel propagated by peristalsis

A mathematical model is developed for electro-osmotic peristaltic pumping of a non-Newtonian liquid in a deformable micro-channel. Stokes’ couple stress fluid model is deployed to represent realistic working liquids. The Poisson-Boltzmann equation for electric potential distribution is implemented owing to the presence of an electrical double layer (EDL) in the micro-channel. Using long wavelength, lubrication theory and Debye-Huckel approximations, the linearized transformed dimensionless boundary value problem is solved analytically. The influence of electro-osmotic parameter (inversely proportional to Debye length), maximum electro-osmotic velocity (a function of external applied electrical field) and couple stress parameter on axial velocity, volumetric flow rate, pressure gradient, local wall shear stress and stream function distributions is evaluated in detail with the aid of graphs. The Newtonian fluid case is retrieved as a special case with vanishing couple stress effects. With increasing couple stress parameter there is a significant elevation in axial pressure gradient whereas the core axial velocity is reduced. An increase in electro-osmotic parameter induces both flow acceleration in the core region (around the channel centreline) and also enhances axial pressure gradient substantially. The study is relevant to simulation of novel smart bio-inspired space pumps, chromatography and medical microscale devices

A bridge from bioimpedance spectroscopy to 50 kHz bioimpedance analysis: application to total body water measurements.

International audienc

Mass Transfers in a Fluidized Bed Bioreactor using Alginate Beads for a Future Bioartificial Liver

International audienc

Recovery of trypsin inhibitor and soy milk protein concentration by dynamic filtration

This paper investigates the feasibility of producing a soy milk fraction enriched in trypsin inhibitor (STI) which could serve as a feed material for chromatographic purification of STI. This STI is also a soy antinutritional factor which is valuable for its medical and scientific applications. We have used a shear-enhanced filtration system with a disk rotating at high speed near the membrane. Stabilized permeate fluxes at 2500 rpm, with a disk equipped with vanes and a transmembrane pressure (TMP) of 67 kPa were 92 L h-1 m-2 with a 50 kDa MWCO PES membrane against 60 L h-1 m-2 with a 300 kDa one, under the same conditions. STI rejection by the 50 kDa membrane was 98.6%. With a smooth disk at a TMP of 107 kPa, fluxes fell to 30 L h-1 m-2 for both membranes, and rejection remained close to 98% for the 50 kDa membrane. During concentration tests, the permeate flux obeyed the logarithmic decay with concentration factor (CF), with a theoretical maximum CF of 4.85. © 2006 Elsevier B.V. All rights reserved.Articl

Recovery of trypsin inhibitor by soy milk ultrafiltration using a rotating disk system

Defatted soy milk was ultrafiltered at 50 kDa using a shear-enhanced rotating disk filtration system developed at the Technological University of Compiegne. The objectives were to concentrate soy milk proteins while removing in the permeate soy trypsin inhibitor (STI) which is an anti-nutritional factor, but can be used for medical applications. Maximum permeate flux at a rotation speed of 2500 rpm, a TMP of 140 kPa and initial concentration, was 37 L h-1m-2 when a smooth disk was used and rose to 95 L h-1m-2 when the disk was equipped with 6 mm high vanes. In concentration tests without permeate recycling, the permeate flux decayed logarithmically with increasing volume reduction ratio (VRR).The maximum theoretical VRR extrapolated to zero flux was found to be 5 for both disks. © 2006.Articl