Numerical Study On Boundary Layer At Stagnation Flow Of Newtonian Fluid

Fluid boundary layer flow is a common phenomenon in scientific research and engineering applications.With the rapid development of the aviation industry,fluid boundary layer theory develops rapidly.Studying the velocity distribution and temperature distribution in the fluid boundary layer is conducive to studying the resistance loss and heat transfer mechanism of the object,to design the fluid machinery that can save energy and improve economic benefits.Therefore,it has attracted many scholars to study the flow and heat transfer of the fluid boundary layer.The main research content of this paper is divided into the following two parts:The First part,a two-dimensional steady forced convection boundary layer viscous incompressible flow of alumina-water nanofluid over a moving permeable vertical flat plate under the effect of a magnetic field normal to the plate is studied in this paper.A mathematical model describing the flow and heat transfer of nanometer magnetic fluid is established.The partial differential control equations and boundary conditions are reduced to be the ordinary differential equations by flow function method.The transformed ordinary differential equations and the boundary conditions treated by the Shooting Method are solved numerically using the Runge-Kutta Method(using MATLAB).Numerical results are obtained for various of the convective heat transfer parameter,the velocity parameter,the power law exponent and the suction parameter.The effects of these parameters on the flow and heat transfer characteristics are determined and discussed in detail.For nanofluids with a volume fraction of 0.1,the increasing of the power law exponential will lead to the increasing of the velocity and the decreasing of the temperature.As the suction parameter increasing,the thickness of the temperature boundary layer will become thinner.In addition,as the convective heat transfer parameter increasing,the thickness of the temperature boundary layer will also increase.The second part,the two-dimensional unsteady stagnation-point flow of a Newtonian fluid on a moving permeable plate is studied.A finite-difference projection scheme(FORTRAN programming)based on staggered mesh is developed.For the detection of unreasonable pressure field,the staggered grid finite difference method is used for spatial discretization.The projection scheme is adopted to solve the decoupling of pressure and velocity in the equation.Adams-Bashforth scheme is used to discretely the nonlinear term in the equation.Finally,the influence of wall moving parameter and mass transfer parameter on velocity boundary layer and fluid morphology of stagnation-point fluid is analyzed and discussed.With the increase of mass transfer parameters,the suction thins the flow boundary layer.With the increasing of wall blowing force,the stagnation point and the shunt line move upward together,and the external region will get thin.And the outer area will be blown out when the wall blowing force reaches a certain value.With the increasing of the motion parameter,the thickness of the velocity boundary layer will get thin.