Investigation of Unsteady Stagnation point flow of nanofluids

Abstract

This study is motivated to understand the time dependent stagnation point flow of nanofluids. Basically, stagnation flow occurs due to the impact of fluid on the solid objects. Near the stagnation point, the flow exhibits the highest heat transfer rate, pressure (static pressure), and mass deposition. According to Bernoulli’s equation when fluid velocity comes to zero it experiences a maximum pressure. It is because kinetic energy of the fluid is converted into pressure known as stagnation pressure (static pressure). Stagnation flows of nanofluids are significant in transpiration cooling (e.g. cooling of a nuclear reactor), reduce friction, and many other industrial and hydrodynamic activities. In this thesis we study the unsteady stagnation point flow of a Newtonian and micropolar nanofluids by considering different types of base fluids and different nanoparticles in two as well as in three dimensions. Also, we studied three types of unsteady stagnation point flow of incompressible nanofluids: plane orthogonal, plane oblique and three dimensional non-axisymmetric by considering different geometries such as two-dimensional horizontal plate, two-dimensional curved shrinking surface and three-dimensional vertical surface. All of the above mention physical problems are transformed into mathematical model using the governing equations of the fluid flow. These equations are then transformed into the set of nonlinear ordinary differential equations. The solutions of transformed equations are obtained via homotopy analysis method, midpoint method with Richardson extrapolation enhancement, shooting mechanism with fifth order R-K Fehlberg technique, bvp4c package in MATLAB, some analytical and perturbation solutions. In order to check the accuracy of the solution methods, comparison is made with the previous results. Also, different observations are made using graph and tables for all the problems under consideration.