Flow over a cylinder

AIM: Simulate the flow over a cylinder for the Reynolds Number.

OBJECTIVES:

• Run a baseline simulation and then calculate the Reynolds number.
• Increase the Reynolds number by a factor of 20%, 40%, and 100%.
• Run the transient flow simulation.
• Calculate flow through time and end time.

REYNOLDS NUMBER

The Reynolds number (Re) is an important dimensionless quantity in fluid mechanics used to help predict flow patterns in different fluid flow situations. At low Reynolds numbers, flows tend to be dominated by laminar flow, while at high Reynolds numbers turbulence results from differences in the fluid's speed and direction, which may sometimes intersect or even move counter to the overall direction of the flow.

Where,

`Re=ρVD/μ`

D = cylinder diameter

μ = dynamic viscosity

ρ = density

V= velocity of fluid

It is used to predict the transition from laminar to turbulent flow for the different problem configuration as follows:

I use air as a fluid and diameter of cylinder is 200 mm so

D = 200 mm =0.2 m

L= 500 mm =0.5 m

μ=1.802 * 10^-5

ρ=1.225 kg/m³

^{`Re=(1.225×V×0.2)/(1.802×10^(-5) )=0.13596×10^5×V`}

For baseline simulation, I used V= 10 m/s

Re=1.3596 * 10⁵

DIFFERENT CONDITIONS

1.For increasement of 20%,

Re=1.63152 * 10⁵ so velocity V=12 m/s

2.For increasement of 40%

Re=1.90344* 10⁵ so velocity V=14 m/s

3.For increasement of 100%

Re=2.7192* 10⁵ so velocity V=20 m/s

CALCULATION OF END TIME

CUT PLOTS

Case 1: For V=10 m/s

Velocity Cut-plot

Animation Link

https://drive.google.com/file/d/1HIbkW94KdOOXwThqXvuWkxLtWM3Qf3Tx/view?usp=sharing

Pressure Cut-plot

Animation Link

https://drive.google.com/file/d/1VcaklWq10itruxTwWhQoQG0h24aHow-s/view?usp=sharing

Case 2: For V=12 m/s

Velocity Cut-plot

Animation Link

https://drive.google.com/file/d/1dYWZ12TdalL34W1x9Bf-bfmcmL4nxMru/view?usp=sharing

Pressure Cut-plot

Animation Link

https://drive.google.com/file/d/17tIkqqdl1XM0hndzEvwdkDEqdNIk-1vD/view?usp=sharing

Case 3: For V=14 m/s

Velocity Cut-plot

Animation Link

https://drive.google.com/file/d/1j5fsCPqjG8xc63RkrSdRUCk0UenbU3V5/view?usp=sharing

Pressure Cut-plot

Animation Link

https://drive.google.com/file/d/1pkGEn0M4xpGSHSK_w8lrKN0yO4Uorfwa/view?usp=sharing

Case 4: For V=20 m/s

Velocity Cut-plot

Animation Link

https://drive.google.com/file/d/1ES3V-Yz7YGbuaHlrp7KwRB3dCZTwOjRi/view?usp=sharing

Pressure Cut-plot

Animation Link

https://drive.google.com/file/d/1ggXmE9N9STDCtH6Lgz4ZGgO4fpLsBV6w/view?usp=sharing

CONCLUSION

• As we increase the Reynolds number Velocity of fluid is also increase because Reynolds number is directly proportional to velocity.
• As velocity increases the pressure at face which is facing fluid flow is increase.

PART FOLDER LINK

https://drive.google.com/drive/folders/1q0kN046vFFWZ32NdXN73dTUH6TSkSds3?usp=sharing