Flow over a cylinder
Abstract : The report explains the flow over a stationary cylinder and results with the pressure and velocity plots.
Aerodynamics (study of flow of air over any body) is absolutely important and plays an integral role in any design that is exposed to atmosphere. It also explains many theories and clarifies many scientific doubts with sincere explanations.
Aim of the project : To run a baseline simulation at a velocity by calculating Reynolds number.
and to differentiate flows with higher Reynolds numbers.
Keywords: Laminar flow, Reynolds number,
Calculations:
Desciption and Procedure: Initially, Reynolds number is calculated at a velocity of 10m/s.
A cylinder is extruded with a diameter of 60mm to a length of 100mm.
Reynolds number is increased to 20%,40%,100% and respective velocities are calculated.
Calculation of flow through time:
Initially, Computational domain length is assumed and flow through time is calculated as distance upon velocity of the flow. Flow end time is twice the flow through time.
When Reynolds number = 33785.78, flow through time = 0.1sec
When Reynolds number = 40540.54, flow through time = 0.083sec
When Reynolds number = 47297.29, flow through time = 0.0714sec
When Reynolds number = 67567.56, flow through time = 0.05sec
Plots:
Pressure cut Plot @ 10 m/s and Reynolds number = 33785.78
velocity cut Plot @ 10 m/s and Reynolds number = 33785.78
Link for velocity animation plot:
Pressure cut Plot @ 12 m/s and Reynolds number = 40540.54
velocity cut Plot @ 12 m/s and Reynolds number = 40540.54
Pressure cut Plot @ 14 m/s and Reynolds number = 47297.292
velocity cut Plot @ 14 m/s and Reynolds number = 47297.292
Pressure cut Plot @ 20 m/s and Reynolds number = 67567.56
velocity cut Plot @ 20 m/s and Reynolds number = 67567.56
Results:
The velocity and pressure plots are plotted and compared for different cases of the velocties and reynolds number.
Inferences and Conclusions: As Reynolds number increases, velocity increases because turbulence increases and turbulence intensity increases.
Accordingly, flow through time decreases.
As it is a stationary cylinder, if Drag force and Lift Force are calculated, Both will be zero.
But , its an ideal case. Generally drag will never me zero as there will be shear effects on each body.
There is no body with zero viscosity.This is called D'Alemberts Paradox.
Rotating cylinder tests can be done for further learning and the circulation calculations can be derived.