Numerical Simulation Research On Flow Characteristics Of Flow Around Cylinder Under Low Reynolds Number Based On Fluent

Flow around a cylinder is a basic and complex fluid mechanics problem.In recent years,with the development of aerodynamics,aerospace technology and ocean engineering,flow around a cylinder has become a hot topic in the academic world.At present,most of the current researches on the flow characteristics of the flow around a cylinder are for the flow around a single cylinder,and there are few research results on the flow around a multi-cylinder.Therefore,starting from actual problems,this paper uses numerical simulation methods to use fluid mechanics numerical simulation software Fluent to mainly study the flow characteristics of multiple cylinders in different arrangements,different spacing ratios,and different diameter ratios.The focus is on the wake morphology and the surface force of each cylinder are analyzed.First of all,this article introduces the research background and status quo of the flow around a cylinder,CFD simulation method,and the structure and characteristics of the Fluent software.Then,Fluent is used to verify the numerical simulation of the flow around a single cylinder to verify that the meshing method and parameter settings used in this paper are accurate and scientific.Next,in the case of Reynolds number Re=100,the numerical simulation of the flow around a single cylinder(circle,ellipse,square,rhombus)of different shapes was carried out,and the velocity change,pressure contour,and vortex of the flow field were derived.Through these results and data,the influence of shape changes on the flow characteristics of the flow around the cylinder is analyzed,and it is found that the flow characteristics of the flow around the cylinder of different shapes are different.The elliptical cylinder has different characteristics in the flow field.Compared with other selected shapes,the resistance and lift are the smallest.In engineering application scenarios that need to overcome the influence of aerodynamics,such as high-voltage transmission towers and bridges,elliptical components can reduce aerodynamic forces,thereby improving safety performance.Secondly,for the flow around multiple parallel cylinders with equal diameters,this article mainly simulates the difference between equal diameter juxtaposed double cylinders with different spacing ratios(L/D=0.5,1.0,1.5,2.0)and equal diameters juxtaposed three cylinders when Reynolds number Re=100 The spacing ratio(L/D=1.5,2.0,2.5,3.0)around the flow,it is found that there is a critical spacing between two parallel cylinders,L/D=2.0,and the critical spacing between three parallel cylinders is about L/D=2.5.When the distance is less than the critical distance,it is difficult to form a regularly distributed vortex street;when the distance is greater than the critical distance,the interaction between the cylinders is weakened,forming a regular symmetrical arrangement of vortex streets;among them,the two cylinders in the flow around the parallel double cylinders are always subjected to resistance.The same,the lift is the same,and the direction is opposite;the force of the upper and lower cylinders in the flow around three parallel cylinders is similar to that of the double cylinders,the resistance of the middle cylinder is always greater than that of the upper and lower cylinders,and the lift is always smaller than that of the upper and lower cylinders,and they all occur with the change of spacing change.Finally,when Reynolds number Re=200 is studied by simulation,the triangle arrangement of three cylinders with different spacing ratios(L/D=1.5,2.0,2.5,3.0)and different diameter ratios(d/D=0.2,0.4,0.6,0.8)The problem of flow,the influence of the change of spacing and diameter on the wake flow pattern of triangularly arranged three cylinders and the force on the surface of each cylinder is studied.It is found that with the expansion of the spacing,the flow field of the triangular-arranged cylinders also changes,and there is also a critical spacing of about L/D=2.0～2.5;the force of each cylinder also changes with the change of the spacing and diameter,and the same diameter is juxtaposed.In the flow around three cylinders,the resistance of each cylinder increases with the increase of the distance,and the resistance and lift of the middle cylinder are always smaller than the other two cylinders.In the flow around three cylinders arranged in a triangular arrangement of unequal diameters,the resistance and lift of the cylinders both increase with the increase of d/D.