Flow over a cylinder

Aim - External Flow Simulation of Flow Over a Cylinder.

Objective -

Simulate the flow over a cylinder for the conditions shown in the video.

• Calculate the baseline case Reynolds number.
  • Re = rho*U_inlet*D/mu
  • D = cylinder diameter
  • mu = dynamic viscosity
  • rho = density
• Run a baseline simulation and then calculate the Reynolds number. Then increase the Reynolds number by a factor of 20%, 40%, and 100% (we will call it a CASE - 1 /2/3 respectively) then run the transient flow simulation.
• Create animations for pressure-velocity for all the three Reynolds number.

• First, we model the cylinder, the diameter of the cylinder is 0.04m and it is extruded to 0.05m

• Since it is flow over a cylinder external flow is selected, and as it is Transient flow simulation we need to do Time-dependency tsest.
• Rest for Velocity we have elected 10m/s in X-Direction.

Observations -

Case - 1

Velocity and Pressure

Case - 2

Velocity and Pressure

Case - 3

Velocity and Pressure

Case - 4

Velocity and Pressure

As provided in the challenge the Reynolds number is varied by 20%,40%,100%

The changes are applied in Parametric Study.

Animations -

Case - 1 Velocity and Pressure

10m/s Velocity

10 m/s Pressure

12m/s Velocity

12m/s Pressure

14m/s Velocity

14m/s Pressure

20m/s Velocity

20m/s Pressure

Conclusion:

• From the above study, we can conclude that the pressure is maximum at the face which is facing the flow direction.
• Velocity is slightly reduced from the input velocity at the side facing the flow direction.
• The velocity is minimum on the other face of the cylinder.
• In the case of Pressure, it can be seen that Pressure kind of builds up in front of the cylinder as air hits the cylinder it opposes the flow resulting the same.
• With an increase in Reynold's number velocity as well as pressure increases which is quite a noticible change.