Non-Newtonian Characteristics of Water Flow in Microchannels

Abstract

Objectives:The rheophysical aspects of non-Newtonian behavior of water flow in thin channels are experimentally examined. The main objective of the research work is to establish the role of electrokinetic potential on the regulation of the rheophysical properties of fluid flow and by decreasing the electrokinetic potential, reducing hydraulic resistance of the system and improving the fluid flow. Method: Microchannel model with different openness value was used. To regulate the electrokinetic potential, antistatic additives were used, the optimal concentration of which was established experimentally. Based on Bingham model, rheological parameters of water flow were estimated at different micro-slit clearances, in the absence and presence of antistatic additive. Findings: It is established that nonlinear rheological effect in water flow in micro-slits is caused by the value of electrokinetic potential, by reducing of which it is possible to significantly weaken the non-Newtonian nature of the fluid. It is also determined that reduction in the electrical potential leads to a significant decrease in the yield shear stress. As a result, up to 20% increase was recorded in the fluid flow through the microcrack model by reducing the electrokinetic potential of the fluid system. Novelty: Previous works revealed that with a decrease in the gap openness in microcracks, starting from a critical size, the viscous liquid exhibits a non-Newtonian character, with the manifestation of an initial pressure gradient and flow locking. However, the main reason behind this phenomena was not fully supported yet. This work is the first scientific work that establish the crucial role of electrokinetic potential on the regulation of the rheophysical properties of fluid flow in microchannels. It is also the first work to determine the possibility of the reduction of the yield shear stress and flow locking in water flow through microchannels by controlling the electrokinetic potential of the system.