Non-Newtonian Fluids in MicroChannel

Electrokinetics is essentially the consequence of a coupling between electrostatics and hydrodynamics. Newtonian hydrodynamics is widely assumed for the classic description of electrokinetics. However, practical applications of electrokinetics frequently deal with biofluids (such as solutions of DNA, blood, and protein, polymeric solutions, and colloid suspensions) which all are complex fluids and therefore demonstrate non-Newtonian behaviors. Recently intensive efforts on electrokinetics of non-Newtonian fluids have been made after Das and Chakraborty [1] who pioneered a theoretical analysis of electroosmosis of non-Newtonian fluids. Here in this entry the example of electroosmosis of non-Newtonian fluids in microchannels is used to demonstrate the fundamental formulation of non-Newtonian electrokinetics. 

Zhao C, Yang C (2011) An exact solution for electroosmosis of non-Newtonian fluids in microchannels. J Non-Newtonian Huid Mech 166(17-18) 1076-1079... 

In a more recent study. Das and Chakraborty [9] presented analytical solutions for velocity, temperature, and concentration distribution in electroosmotic flows of non-Newtonian fluids in microchannels. A brief description of their transport model is summarized here, for the sake of completeness. A schematic diagram of the parallel plate microchannel configuration, as considered by the above authors, is depicted in Fig. 2. The bottom plate is denoted as y = H and top plate as y = +H. A potential gradient is applied along the axis of the channel, which provides the necessary driving force for electroosmotic flow. The governing equations appropriate to the physical problem are the equations for conservation... 

Non-Newtonian Fluids in MicroChannel, Fig. 2 Schematic diagram depicting a parallel plate microchannel... 

Elastic turbulence One final topic we will mention here before closing the chapter is the elastic turbulence. The term describes the turbulence caused by the elastic forces arising in non-Newtonian fluids. In the situations where mixing is needed, the elastic forces in a non-Newtonian fluid can be used to create turbulence. The analysis by Joo and Shaqfeh (1992) is particularly useful for the flow of non-Newtonian fluids in microchannels but is beyond the scope of the text here. 

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