Transient flow over the cylinder

AIM

Calculation of Reynolds number and run a simulation over the cylinder by varying the Reynolds number by a factor of 20%, 40%, and 100% and create cut plots and animation for the pressure and velocity over the cylinder using Solidworks Flow Simulation wizard.

THEORY

It is a dimensionless number helps in determining the nature of the flow. For flow over the cylinder, the Reynolds number can be calculated as:

`Reynolds Number = (rho*v*l)/mu`

Where, `rho =` density of the fluid

v = velocity of the fluid

l = characteristic length

`mu =`Dynamic viscosity of the fluid

CALCULATION

Here, It has been assumed that the length and diameter of the cylinder are 0.03m and the baseline velocity is assumed to be 10 m/s. Medium inside the domain is air. The dynamic viscosity of air is `1.81*10^-5 PaS`. The density of air is 1.225 kg/m3

Therefore, Reynolds Number = `(1.225*10*0.03)/(1.81*10^-5)`

= 20303.86

On increasing the Reynolds number by 20, 40, 100% the corresponding values are 24364.64, 28425.41 and 40607.7 respectively. The corresponding velocities for the following Reynolds number are 12, 14 and 20 m/s respectively.

SIMULATION USING SOLIDWORKS

• Create a cylinder of length and diameter 0.3 m and save the file in solid works. Open the flow simulation wizard and set the flow as external, provide transient flow parameters like total simulation time and output step times.
• Set the inlet baseline velocity of air as 10 m/sec in the x-direction. Create cut plots to monitor visualize the pressure and velocity over the cylinder in the XY plane.
• Using the animation wizard the video has been created for 10 seconds for different output steps and saved on the disk.
• The same procedure has been carried out for the different velocities of air and the cut plots have been compared for different Reynolds number

CUT PLOTS & ANIMATIONS

Case-1) Baseline Reynolds Number (Air inlet velocity = 10 m/sec)

a) Pressure contour at 10 m/sec

b) Pressure Cutplot Animation:

https://drive.google.com/open?id=1QN_lHSBxum-mTEdixmrZjMWn-KbG_Rda

c) Velocity Contour at 10m/sec

d)Velocity cut plot animation at 10m/sec:

https://drive.google.com/file/d/1IT1R9606FYqweGl_y80mBvAHorLaw5C2/view?usp=sharing

Case-2) Reynolds Number increased by 20% (Air inlet velocity = 12 m/sec)

a) Pressure contour at 12 m/sec

b) Pressure Cutplot Animation:

https://drive.google.com/file/d/1zDnq6T0deQw7VRAt_to5lwl2UlasysWS/view?usp=sharing

c) Velocity Contour at 12m/sec

d)Velocity cut plot animation at 12m/sec:

https://drive.google.com/file/d/1r9dD9-HEHzTZj0_3lkknk9HEHYpNMY3w/view?usp=sharing

Case-3) Reynolds Number increased by 40% (Air inlet velocity = 14 m/sec)

a) Pressure contour at 14 m/sec

b) Pressure Cutplot Animation:

https://drive.google.com/file/d/10zOzYFhssp4he2NRjSA7PBcDmexs0-TG/view?usp=sharing

c) Velocity Contour at 14m/sec

d)Velocity cut plot animation at 14m/sec:

https://drive.google.com/file/d/1CNBJiMMfkzqo4BUn47cLQVBt-_0Qfkzi/view?usp=sharing

Case-4) Reynolds Number increased by 100% (Air inlet velocity = 20 m/sec)

a) Pressure contour at 20 m/sec

b) Pressure Cutplot Animation:

https://drive.google.com/file/d/1RgGp9Vm4zKtVj3GGK-JSHEEse16I5o_R/view?usp=sharing

c) Velocity Contour at 20m/sec:

d)Velocity cut plot animation at 20m/sec:

https://drive.google.com/file/d/1QugqmRuW3QB6hf3cWrneLqC1KQZCFbRt/view?usp=sharing

CONCLUSION

The cut plots and animation files have created using the Flow simulation wizard in SolidWorks. On increasing the Reynolds number, the velocity and the pressure have been increased.