FLOW SIMULATION OF FLOW OVER CYLINDER USING SOLIDWORKS

AIM

To run a simulation for flow over cylinder with a specific base line Reynolds no. after that increase the Reynolds number by a factor of 20%, 40%, and 100% then run the flow simulation.

FORMULA USED

Reynolds number,

`Re = (ρ U D)/µ = (U D)/ⱴ`

R_e = Reynolds number

ρ= density of the fluid

U= Inlet velocity of the fluid

D = Characteristic diameter

µ= dynamic viscosity of the fluid

ⱴ= kinematic viscosity of the fluid

CONDITION FOR BASELINE SIMULATION

INPUTS	VALUES
Inlet velocity	10 m/s
Analysis type	External
Fluid	Air
Time Dependent	Total analysis time : 0.1s
	Output time step : 0.01s
Mess size	x= 300, y=300, z=300

CALCULATION

The behavior of air is different for different temperature. So, I have assumed that the air is to be at Atmospheric pressure. And the temperature is 25 degree Celsius. Corresponding to 25 degree Celsius the physical properties are given in the figure below.

From the above table for 25 degree Celsius inlet condition, the base line Reynolds no.

`Re = (ρ U D)/µ`

`Re = (1.184 * 10 * 0.05)/(1.85 * 10^-5)`

R_e = 32000

For end time,

End time = 2 x Flow through time

Flow through time = Length of domain/ Inlet velocity

Length of domain = 0.45m

Inlet velocity = 10 m/s

Flow through time = `0.45/10`

Flow through time = 0.045 sec

End time = 2 x 0.045

End time = 0.09 sec

For baseline, Reynolds no. = 32000, V= 10 m/s, End time = 0.09 sec

At 20% increment

Reynolds no. = 38400 , V= 12 m/s, End time = 0.075 sec

At 40% increment

Reynolds no. = 44800 , V= 14 m/s, End time = 0.064 sec

At 100% increment

Reynolds no. = 64000 , V= 20 m/s, End time = 0.045 sec

STEPS FOR DESIGNING CYLINDER

Before starting design make sure that the unit is in metre

1. First select the front plane for sketch after that draw the circle of dimension as shown in the figure

2. Extrude the design with 0.1m of length as shown in the figure

3. Now the design is over.

STEPS FOR FLOW ANALYSIS

Before starting flow simulation first enable the flow simulation from the solidworks add ins

1. Go to the WIZARD option to start a flow simulation. After that one dialog box will appear. Write project name which you want to give the name to it. After that click on next.

2. when you hit the next button it asks to set the unit system. For my project i used as SI unit. After that click on next button.

3. After click on next it will ask to define the flow type whether it is external or Internal. My aim is to study outside the cylinder so I used external.

There are several additional features also present like gravity, time dependent etc select the option if required in study. After that hit next button.

I have used time dependent option as mentioned in the figure.

4. After that select the fluid which you want to take in your study and click on add button in order to add the fluid.

5. After that choose roughness of the wall if it has otherwise click on next.
6. After that provide essential details like velocity and click finish button. Here I am taking 10m/s velocity in X-direction.

7. After that your design will be enclosed in the chamber which is our domain of interest as shown in figure below. If you want to edit the enclosed box then right click on computational domain and choose edit definition option. Here I have given the dimension of CFD domain is

8. After that right click on mesh option and select edit option in order to change the basic mesh to achieve better result as shown in figure. After that click ok

9. Click on run option after which one dialog box will be appear select new calculation and click on ok button in order to obtain the result
10. Now click on results option and right click on cut plot and select the insert option.

11. similar way do for pressure also and you will see the cut plot for velocity and pressure in two different cut plot.

STEPS FOR ANIMATION

1. Right click on animation option from the result and select insert as shown in figure.

2. After that click on wizard option and the one dialog box will be appeared. Provide the information in it and click on next option.

3. after that click on rotation option if your design is having any rotation part otherwise click on next. Here in my case any rotation is not present.

4. Here we are interested in scenario so we select scenario option and click on next button

5. after that click on finish button.
6. After that moves all the point properly so that all starts from same point and end at the same point.
7. Now click on run button to view the animation.

RESULTS

Flow over cylinder for baseline when Reynolds number is 32000 and velocity is 10m/s.

Velocity cut plot contour at 10 m/s

Animation of velocity at 10 m/s

Pressure cut plot contour at 10 m/s

Animation of pressure at 10 m/s

CASE1. When Reynold no. is 20% more of baseline and velocity is 12 m/s.

Velocity cut plot contour at 12 m/s

Animation of velocity at 12 m/s

Pressure cut plot contour at 12 m/s

Animation of pressure at 12 m/s

CASE2. When Reynold no. is 40% more of baseline and velocity is 14 m/s.

Velocity cut plot contour at 14 m/s

Animation of velocity at 14 m/s

Pressure cut plot contour at 14 m/s

Animation of pressure at 14 m/s

CASE3. When Reynold no. is 100% more of baseline and velocity is 20 m/s.

Velocity cut plot contour at 20 m/s

Animation of velocity at 20 m/s

Pressure cut plot contour 20 m/s

Animation of pressure at 20 m/s

CONCLUSION

1. For different Reynolds no. whether 32000,38400,44800 and 64000 the Maximum velocity obtain are 12.122 m/s, 14.503 m/s, 17.006 m/s and 24.256 m/s.
2. For different Reynolds no. whether 32000,38400,44800 and 64000 the Maximum pressure obtain are 101383.55 Pa, 101409.27 Pa, 101439.60 Pa and 101558.64 Pa.
3. It is cleared that when we increase the base line Reynolds no. by 20%, 40%, and 100% the velocity increases but the pressure increment is not very much significant it is almost negligible.
4. The flow become more convergent towards the output side.
5. The variation is seen mainly after the right side of the cylinder i.e. toward output side.
6. The high pressure is generated near the inlet side of the cylinder i.e. left side in the plot.

REFERENCES

1. Video lecture of skill lync
2. Wikkipedia