UNSTEADY ELECTROOSMOTIC FLOW AND HEAT TRANSFER CHARACTERISTICS OF A CLASS OF BIOFLUIDS IN PARALLEL PLATE MICROCHANNELS UNDER HIGH WALL ZETA POTENTIAL

The unsteady electroosmotic flow and heat transfer characteristics of a class of biological fluids, namely blood containing suspended trace elements, in a microchannel bounded by two parallel plates driven by an external alternating electric and magnetic field at high wall Zeta potential are studied. Blood is regarded as a uniform and incompressible micropolar fluid, and its properties are analyzed mathematically. First, under the condition that Debye-Hückel (D-H) linear approximation was not used, the coupled equations of motion were developed by the perturbation method, and then the equations were solved by the finite difference method, and the numerical solution was given. Under the low wall Zeta potential, the numerical solution was compared with the analytical solution obtained by using D-H linear approximation. The reliability of the numerical method in this paper was proved. Secondly, the influences of wall Zeta potential, micropolar viscosity, Debye-Hückel (D-H) parameters, concentration coefficient and Hartmann number on fluid flow characteristics were discussed, and the influences of Prandtl number and Brinkmann number on heat transfer characteristics were explored. The results show that: (1) the wall Zeta potential plays an important role in regulating the fluid motion characteristics, as the wall Zeta potential value keeps increasing, both the fluid velocity and micro-rotation will magnify accordingly, not only that, but it also leads to an expansion in temperature, this phenomenon clearly indicates that, compared with the case of low wall Zeta potential, high wall Zeta potential has a significant promoting effect on the electroosmotic flow process of micro-polar fluids; (2) at high wall Zeta potential, the micropolar viscosity enlarges, blood velocity and micro-rotation decrease, and heat transfer minishes; (3) at high wall Zeta potential, with the increase of D-H parameters and concentration coefficient, the speed and micro-rotation of blood are increased, and the temperature is magnified; (4) at high wall Zeta potential, the applied magnetic field obviously inhibits the fluid velocity; (5) at high wall Zeta potential, the augment of Prandtl number and Brinkmann number will promote the heat transfer of the fluid, causing the temperature to rise.