Project

Flow over a cylinder using Solidworks

AIM : To simulate the transient state flow over a cylinder.

OBJECTIVES :

To run a baseline simulation and then calculate the Reynolds number.
To increase the Reynolds number by a factor of 20%, 40%, and 100% then run the transient flow simulation.

INTRODUCTION :

Steady State	Transient State
The steady state is the state that is established after a certain time in your system.	The transient state is basically between the beginning of the event and the steady state.
Steady State occurs after the system becomes settled and at the Steady State system works normally. It depends on the forcing function i.e. source	Transient response can be referred as the the system’s instant behaviour against input change or disturbance. In other words, ‘How system reacts against the inputs’.

PROCEDURE :

Geometry Modelling of the cylinder -
This is a very simple process as a cylinder is modelled by drawing a circle in either of the three planes (for our case it's front plane) and is extruded to get a cylinderical shape. At first a circle of diameter `50 mm` was drawn and was extruded to a length of `100 mm`and was saved.

Flow Simulation Setup -
After geometry modelling, flow simulation was setup using wizard tool and the following inputs were given,
Analysis type : External and Time Dependent with Simulation Time of `0.1` seconds and Time Step of `0.01` seconds, as length of domain = `0.5m` and time = `frac(l)v`
Type of fluid : Air
Type of Flow : Laminar and Turbulant,
Wall Conditions : Adiabatic with 0 micro-meter roughness,
Initial Conditions : Pressure(101325 Pa), Temperature(293.2 K), Velocity x-direction(10 m/sec).
In addition a fine mesh was provided to global and a local level by selecting curved face of cylinder.

Reynold's Number (`R_e`) = `(rho*v*D)/(mu)`,
For air at 293.2 K and 101325 Pa, density `(rho) = 1.2041((kg)/m^3)`,dynamic viscosity `(mu) = 1.825``*10^-5 (kg)/(m*sec)`,
From theses data, the Reynold's Number (`R_e`) can be calculated and it comes out to be `32989.041`.
Now according to the challenge statement, transient simulations has to be done by increasing `R_e` by a factor of `20%`,`40%`,`100%`,
Case 1 : When it is increased by `20%` , new `R_e = 39586.85` and velocity = `12(m/sec)`,
Case 2 : When it is increased by `40%` , new `R_e = 46184.65` and velocity = `14(m/sec)`
Case 1 : When it is increased by `100%` , new `R_e = 65978.08` and velocity = `20(m/sec)`
The length of computational domain is set to be `0.5m`, Hence for velocity = `10 m/s`,Simulation end time = `0.1sec`,
For velocity = `12 m/s`,Simulation end time = `0.0833sec`,
For velocity = `14 m/s`,Simulation end time = `0.0714sec`,
For velocity = `20 m/s`,Simulation end time = `0.05sec`,
Now three simulations have to be run for the given simulation time with suitable Step Size.
After Simulations animations is created with animation wizard.

RESULTS :

For velocity = `10m/s`, cut plots for velocity and pressure are obtained by using front plane.
Velocity Cut Plot -

Case 1: For velocity = `12m/s`, cut plots for velocity and pressure are obtained by using front plane.
Velocity Cut Plot -

Case 2: For velocity = `14m/s`, cut plots for velocity and pressure are obtained by using front plane.
Velocity Cut Plot -

Case 3: For velocity = `20m/s`, cut plots for velocity and pressure are obtained by using front plane.
Velocity Cut Plot -

CONCLUSION :

As velocity of flow increases, Reynold's Number increases and flow changes from Laminar to Turbulant.
As velocity strikes the front face of cylinder, there is slight drop in the velocity and gradually increases over the cylinder.
There is pressure difference between the front and back face of the cylinder.
Vortex Formation takes place at the side of the cylinder which is opposite to velocity flow.

NOTE : All the animations are placed in the google drive- link

Ship work like this
in your own course.