Flow over a cylinder
AIM: Simulate the flow over a cylinder for the conditions of change in Reynolds number by 20%, 40%, 100% and compare the velocity and pressure study.
Show and explain the entire case setup:
geometry of the fig: dia:0.04 m, height:0.05m
model: Computation Domine:
Mesh: CUTPLOT:
Results and explanation:
Since the Reynolds number(Re) is
- Re = rho*U_inlet*D/mu
- D = cylinder diameter
- mu = dynamic viscosity
- rho = density
Calculate the Reynolds number:
Here all the values are the same except the velocity. Then increase the Reynolds number by a factor of 20%, 40%, and 100% is nothing but change in velocity by a factor of 20%, 40%, and 100% then run the transient flow simulation.
Therefore, we have considered the initial velocity to be 10 m/s and the corresponding values are 12 m/s, 14 m/s, 20 m/s.
Calculating the time:
Speed=distance/time.
Therefore, time=distance /speed.
Distance= pi*diameter/2=0.062 m.
Speed= initial velocity= 10 m/s.
Therefore, time=0.07 s.
Results:
At v=10 m/s:
At the point of impact, the velocity is dropped by some value and when it moved over the circumference of the cylinder it value has been greater than the initial value. And when the fluid reaches the tail end of the cylinder again the velocity has dropped further and it gradually increases after the floe travel a certain distance.
At the point of impact, the pressure is high on the surface of the cylinder it slowly dropped when the flow is moved over the circumference of the cylinder. After the fluid moves away from the cylinder again the pressure increases to the initial value.
velocity: Pressure:
At v=12 m/s:
At the point of impact, the velocity is dropped by some value and when it moved over the circumference of the cylinder it value has been greater than the initial value and also greater than the v=10 m/s at this position. And when the fluid reaches the tail end of the cylinder again the velocity has dropped further and it gradually increases after the floe travel a certain distance.
At the point of impact, the pressure is high on the surface of the cylinder it slowly dropped greater than the previous case when the flow is moved over the circumference of the cylinder. After the fluid moves away from the cylinder again the pressure increases to the initial value.
Velocity: Pressure:
At v=14 m/s:
At the point of impact, the velocity is dropped by some value and when it moved over the circumference of the cylinder it value has been greater than the initial value and also greater than the v=12 m/s at this position. And when the fluid reaches to the tail end of the cylinder again the velocity has dropped further and it gradually increases after the floe travel a certain distance the region of the velocity increase is high when compared to previous cases.
At the point of impact, the pressure is high on the surface of the cylinder it slowly dropped greater than the previous case when the flow is moved over the circumference of the cylinder and the region of pressure drop is higher when compared to previous cases. After the fluid moves away from the cylinder again the pressure increases to the initial value.
Velocity: Pressure:
At v=20 m/s:
At the point of impact, the velocity is dropped by some value and when it moved over the circumference of the cylinder it value has been greater than the initial value and also greater than the v=14 m/s at this position. And when the fluid reaches the tail end of the cylinder again the velocity has dropped further and it gradually increases after the floe travel a certain distance the region of the velocity increase is 2 times high when compared to previous cases.
At the point of impact, the pressure is high on the surface of the cylinder it slowly dropped greater than the previous case when the flow is moved over the circumference of the cylinder and the region of pressure drop is 2 times higher when compared to the previous cases. After the fluid move away from the cylinder again the pressure increases to the initial value for the higher region.
Velocity: Pressure:
VELOCITY ANIMATION LINK OF ALL CASES:
https://drive.google.com/drive/folders/1EAF8AwKi-9W6UfIrHsqIoHO9osGdXKZp?usp=sharing
PRESSURE ANIMATION LINK OF ALL CASES:
https://drive.google.com/drive/folders/1TC-vY0rI59Lh0k4GuvNxV92GTzFo4qzH?usp=sharing