Flow over a cylinder

Aim/Objective: Flow over a cylinder

Theory:

CFD has fascinated researchers, as it is a fast, accurate and reliable method of analyzing the variation of hydrodynamic properties of the flow over and within a body. Computational Fluid Dynamics (CFD) is a branch of fluid mechanics that uses numerical methods and algorithms to solve complex problems involving fluid flow.

Reynold's Number

Reynolds number can reveal whether the flow is laminar or turbulent. The transition from laminar to turbulent flow depends on the surface roughness, flow velocity, geometry, surface temperature, and type of fluid, among others.

Formulation:

Calculation:

Velocity = Distance / time

Time = Distance / velocity i.e. Time = 0.75/10 = 0.075 sec

The length of the domain along the X axis is 0.750 m

When the Velocity is 10 m/s for Re = 40518.19 then Simulation end time = 0.15 sec

Given that the end time should be 2 times the flow through time

At Baseline For V = 10 m/s , Re = 40518.19 , Simulation end time = 0.150 sec

At 20% For V = 12 m/s , Re = 48621.83 , Simulation end time = 0.125 sec

At 40% For V = 14 m/s , Re = 56725.46 , Simulation end time = 0.107 sec

At 100% For V = 20 m/s , Re = 81036.38 , Simulation end time = 0.075 sec

From this we can see that the Velocity increases the time decreases.

Results:

Velocity Contour :

Pressure :

Case 1: Flow over a cylinder at 20% of Reynolds Number i.e. @12m/s

Velocity Contour :

Pressure :

Case 2: Flow over a cylinder at 40% of Reynolds Number i.e. @14m/s

Velocity Contour :

Pressure :

Conclusion:

Reynold's number increases the Velocity increases and the flow through time decreases.