Flow Simulation Over a Cylinder Using Solidworks

Flow Simulation Over a Cylinder Using Solidworks

Aim:- To perform flow simulation on flow over the surface of cylinder and calculation pressure and velocity of different reynolds number

Theory:-

External flows past objects have been studied extensively because of their many practical applications. For example, airfoils are made into streamline shapes in order to increase the lifts, and at the same time, reducing the aerodynamic drags exerted on the wings. On the other hand, flow past a blunt body, such as a circular cylinder, usually experiences boundary layer separation and very strong flow oscillations in the wake region behind the body. In certain Reynolds number range, a periodic flow motion will develop in the wake as a result of boundary layer vortice being shed alternatively from either side of the cylinder. This regular pattern of vortices in the wake is called a Karman vortex street. It creates an oscillating flow at a discrete frequency that is correlated to the Reynolds number of the flow. The periodic nature of the vortex shedding phenomenon can sometimes lead to unwanted structural vibrations, especially when the shedding frequency matches one of the resonant frequencies of the structure. One example is the famous Tacoma bridge link and this topic has been discussed in great details in the Tacoma bridge link. In this presentation, we are going to investigate the flow past a circular cylinder and study the turbulent wake flow field using the PIV Technique.

In mathematics, potential flow around a circular cylinder is a classical solution for the flow of an inviscid, incompressible fluid around a cylinder that is transverse to the flow. Far from the cylinder, the flow is unidirectional and uniform. The flow has no vorticity and thus the velocity field is irrational and can be modeled as a potential flow. Unlike a real fluid, this solution indicates a net zero drag on the body, a result known as D'Alemberts principle.

Reynold's Number:-

he Reynolds number is the ratio of inertial forces to viscous forces within a fluid which is subjected to relative internal movement due to different fluid velocities. A region where these forces change behavior is known as a boundary layers, such as the bounding surface in the interior of a pipe. A similar effect is created by the introduction of a stream of high-velocity fluid into a low-velocity fluid, such as the hot gases emitted from a flame in air. This relative movement generates fluid friction, which is a factor in developing turbulent flow. Counteracting this effect is the viscosity of the fluid, which tends to inhibit turbulence. The Reynolds number quantifies the relative importance of these two types of forces for given flow conditions, and is a guide to when turbulent flow will occur in a particular situation.

The Reynolds number is defined as

{\displaystyle \mathrm {Re} ={\frac {\rho uD}{\mu }}={\frac {uD}{\nu }}}

where:

• ρ is the density of the fluid
• u is the flow speed(m/s)
• D is the diameter of the tube (m)
• μ is the dynamic viscosity of the fluid (Pa·s or N·s/m² or kg/(m·s))
• ν is the kinematic viscosity of the fluid (m²/s).

Dimensions:-

Diameter of Cylinder(D)= 0.1m

Length of cylinder(L)= 0.2m

Inlet velocity= 10m/s

Dynamic Viscosity:- 18.14*10^-6 Ns/m^2

Density= 1.225 kg/m^3

Calculation:-

Reynolds Number= 67530.32

At 20% Re= 81036.38

At 40% Re= 94542.48

At 100% Re=135060.64

Computational domain view of Cylinder:-

Fine mesh view of Cylinder:-

Results Of Simulation:-

At velocity 10m/s i.e Initial Velocity

Pressure at inital velocity

At Velocity 12m/s (20%):-

In this plot their is very minor difference than in above plot of intial velocity

Pressure plot for 12m/s velocity

At Velocity 14 m/s (40%):-

Pressure at 14m/s velocity:-

At Velocity 20 m/s (100%):-

Pressure at 20 m/s velocity:-

Video Link of Velocity and Pressure Flow Simulation Animation:-

https://drive.google.com/drive/folders/1WBYkTppYRxI2Q2HZCjq-wQ-_-Y5xnFSk?usp=sharing

Conclusions:-

From the result plots at different velocity and reynolds number it can be concluded that the contour between all the three plots are not so different it differs each other by a small quantity.