Unsteady Oblique Stagnation-point Flow Of Maxwell Fluid And Oldroyd-B Fluid

The phenomenon of oblique stagnation point flow can occur in processes such as polymer extrusion,wire coating,fluid transportation equipment for treating stainless steel,plastic sheet stretching,and food processing.This paper mainly studies the oblique stagnation point flow,heat and mass transfer of Maxwell fluid and Oldroyd-B fluid,and analyzes the effects of dimensionless parameters on flow rate,temperature,and concentration.This has theoretical significance for guiding practical problems.The research content is divided into the following three parts:The first part investigates the oblique stagnation point flow and heat transfer problem of Maxwell fluid on oscillating stretching/shrinking plates.Firstly,according to the characteristics of oblique stagnation point flow,a method to analyze the pressure in the flow field by solving ordinary differential equation is proposed.Then,a special stream function is used for similarity transformation to obtain a system of partial differential equations with time and a single spatial variable.Finally,an approximate analytical solution of the unsteady oblique stagnation point flow is obtained using the Homotopy Analysis Method,and a graph is drawn to intuitively represent the trend of flow and heat transfer in the flow field.The results show that when the plate is in a tensile state,the flow lines near the stagnation point are dispersed on both sides with the stagnation point as the center;when the plate is in a contraction state,the streamline near the stagnation point is concentrated near the stagnation point.An increase in velocity ratio parameter will cause an increase in pressure gradient and promote fluid flow.In the second part,the unsteady oblique stagnation point flow,heat transfer,and mass transfer of Oldroyd-B nanomagnetic fluid on an oscillating stretch plate were investigated.Firstly,following the research approach of the first part,the expression for the pressure term was determined.Secondly,the Cattaneo-Christov double diffusion model was coupled with the Buongiorno model to modify the heat and mass transfer model.Simultaneously considering the influence of inclined uniform magnetic field and velocity slip on fluid flow.Finally,a special flow function is used for similarity transformation,and the Homotopy Analysis Method is used to obtain an approximate analytical solution for the oblique stagnation point flow.The results show that the thermal relaxation effect and the concentration relaxation effect show a trend of first increasing and then decreasing on the temperature and concentration distribution of nanofluids.Increasing the angle of the tilted magnetic field within a certain range can hinder the flow of nanofluids.The third part discusses the unsteady oblique stagnation point flow of Maxwell fluid impacting a cylinder.The partial differential equations obtained by similarity transformation of the control equation are numerically solved using the Newton Iterative-Chebyshev Spectral Method.The results indicate that the larger the curvature of the cylinder,the greater the velocity of fluid particles at the same time and location;unsteady parameters and fluid memory properties can also hinder fluid flow near the wall.