Peristalsis of Nanoliquids in Presence of Partial Slip Condition

Abstract

Heat transfer enhancement determines the need for new innovative coolants with improved performance. The new concept of nanofluids has been introduced to make the performance of heat transfer fluids better. The concept of nanofluid has been advanced by S. Choi [1] who showed considerable increase of heat transported in suspensions of copper and aluminium nanoparticles in water and other liquids. Nanofluids are a new kind of fluids which are dispersions of nanoparticles in liquids that are permanently suspended in base fluid. By using different particles which are mostly metals (Cu, Ag, Au), metallic oxides (CuO, Al₂O₃, TiO₂, ZnO), nitride/carbide ceramics (AlN, SiN, SiC, TiC) and carbon nanotubes etc, the engineers created wide range of nanofluids with completely new properties. These heat exchange fluids present interesting heat transfer features when compared with more conventional coolants. Considerable research on thermal conductivity and convective heat transfer of nanofluidsis done. In fact, applications of nanofluids such as coolant in automobiles, heat exchangers in industries etc appear promising with these characteristics. Several experimental and theoretical research activities for nanofluidsare performed which can be seen through the studies [2-14]. Peristaltic flow refers to the transportation of fluid inside a channel or tube by the action of flexible walls. It is the major mechanism for fluid flow in many biological and industrial systems. Within human body it is involved for swallowing food through esophagus, movement of chyme in the gastro-intestinal track, in the dustusefferentes of the male reproductive system, vasomotion of small blood vessels such as arterioles, vanules and capillaries etc. Peristaltic pumps are used to transport corrosive or very pure materials so as to avoid direct contact of the fluid with the pump's internal surface. Many biomedical devices such as dialysis machines, open heart bypass pump machines, infusion pumps etc are engineered on the mechanism of peristalsis. Shapiro [15] analyzed the peristaltic pumping in a two dimensional flexible tube. Later on the theoretical results obtained by [15] were confirmed experimentally by Weinberg [16]. Some recent researches dealing with the peristaltic motion are mentioned in the refs. [17-25]. It is well admitted fact that the tabular organs facilitating fluid flow in the human body are internally lubricated with mucus and secretion layer. These layers in turn prevent the fluid from sticking to the walls. In that type of cases the no slip conditions between the fluid and the boundary is not valid. Therefore it seems important to consider slip condition in such situations.Another important phenomena widely encountered in industrial and engineering applications and attainted the attention of researchers is mixed convection. Ocean current, seawind formation, formation of microstructure during the cooling of molten metals etcinvolve mixed convection. Moreover this phenomenon is utilized in heat exchangers, removal of nuclear waste and in modern cooling /heating system. Having such facts in mind, the present dissertation is arranged as follows. In the first chapter of this dissertation, explanation of some basic concepts and law relevant to materials utilized in the next two chapters is provided. These basic concepts include peristalsis, nanofluids, heat transfer mechanisms, two phase model for nanofluids, continuity equation, momentum equation, energy equation etc. The second chapter comprises the work of Shehzadet. al.[38]. In this study the five different nanofluids are considered to discuss the peristaltic transport in a symmetric channel. The two two phase models namely Maxwell and Hamilton-Crosser are considered for the analysis. The study consists of comparison between the results obtained by two phase models.Comparison for the five different water based nanofluids is studied. In the third chapter, consideration is given to the flow of incompressible water based nanofluidssubject to five different types of nanoparticles including metallic and metallic oxides. Here the effects of velocity and thermal slip on the peristaltic transport of nanofluids in asymmetric channel are especially studied. Energy equation is utilized in view of constant heat source /sink parameter. Two thermal conductivity models Maxwell's and Hamilton-Crosser's [44, 45] are used to compare the results for different nanofluids.