Flow over Cylinder for different Reynold's Number

Aim : Perform CFD simulation on external flow over a cylinder with different reynolds number

Theory : Reynolds number tells us whether flow is laminar or turbulent

Re = ( ρ V D ) / μ

Re = reynolds number ; ρ = density ; V = velocity ; D = diameter ; μ = viscosity

Case setup :

Diameter = 0.02 m

Length = 0.05 m

Fluid = Air (rest of the conditions default, time dependant, external flow)

ρ = 1.225 kg/m^3

μ = 1.81 x 10^-5 kg/ms

Global Mesh level = 7

Calculate Re for base condition (v=10 m/s) using above given formula

Re = 13535.9116

+20% = 16243.09392

+40% = 18950.27624

+100% = 27071.8232

Hence calculating velocity for the 3 cases = 12m/s ; 14 m/s and 20 m/s

Procedure :

Create cylinder using sketch and extrude commands with the given dimensions

Then go to flow simulation workbench and launch wizard. Input reqd conditions such as air as medium, time dependant flow, external flow etc.

Insert cut plots between the cylinder for velocity and pressure

Run the simulation

Repeat for all 3 values of velocity for different reynolds number

Results :

V= 10m/s :-

V= 12m/s :-

V= 14m/s

V = 20 m/s

Conclusion : Velocity and pressure increasing with reynolds number. velocity is highest on the front side of cylinder as can be seen clearly in the cut plots.