FLOW SIMULATION OVER A CYLINDER IN SOLIDWORKS

AIM: TO SIMULATE FLOW OVER A CYLINDER AT VARYING REYNOLDS NUMBER USING SOLIDWORKS

INTRODUCTION: In mathematics, potential flow around a circular cylinder is a classical solution for the flow of an inviscid, incompressible fluid around a cylinder that is transverse to the flow. Far from the cylinder, the flow is unidirectional and uniform. The flow has no vorticity and thus the velocity field is irrotational and can be modeled as a potential flow. Unlike a real fluid, this solution indicates a net-zero drag on the body, a result known as d'Alembert's paradox.

GOVERNING EQUATIONS:

REYNOLDS NUMBER –

`Re= (ρ×v×D)/μ`

where,

`ρ=`Density of Fluid (kg/m³)

`v=`Inlet Velocity of Fluid (m/s)

`D=`Inlet Diameter (m)

`μ=`Dynamic Viscosity of Fluid (Pa.s)

OBJECTIVE:

• Running a baseline simulation and calculating the Reynolds Number
• Running simulations by increasing the Reynolds Number by a factor of 20%, 40% and 100%
• Creating Pressure Velocity animations all the simulated cases

PROCEDURE:

• Initially, a 3D model of a cylinder is constructed according to our convenience for a specific Velocity and Reynolds Number.
• Flow Simulation is set up for a Transient External Flow and an Inlet Velocity of 10 m/s is specified. The 3D Computational Domain is built with respect to “Flow Through Time”.
• After Building the Mesh, the simulation is carried out and the Cut Plots for Velocity and Pressure are plotted.
• Animations are set up for both the Velocity and Pressure Contours and saved in ‘.avi’ format.

CALCULATIONS:

END TIME –

End Time = 2*Flow Through Time

where,

Flow Through Time = Domain length / Inlet Velocity

(The Domain length is already specified at 0.40m)

Therefore, End-Time comes out to be 0.08s at an Inlet velocity of 10 m/s.

RESULTS:

• CASE 1 - v = 10 m/s (Baseline Reynolds number)

VELOCITY CUT PLOT

PRESSURE CUT PLOT

ANIMATION

VELOCITY CONTOUR

PRESSURE CONTOUR

• CASE 2 - v = 12 m/s (20% of Baseline Reynolds Number)

VELOCITY CUT PLOT

PRESSURE CUT PLOT

ANIMATION

VELOCITY CONTOUR

PRESSURE CONTOUR

• CASE 3 - v = 14 m/s (40% of Baseline Reynolds Number)

VELOCITY CUT PLOT

PRESSURE CUT PLOT

ANIMATION

VELOCITY CONTOUR

PRESSURE CONTOUR

• CASE 4 - v = 20 m/s (100% of Baseline Reynolds Number)

VELOCITY CUT PLOT

PRESSURE CUT PLOT

ANIMATION

VELOCITY CONTOUR

PRESSURE CONTOUR

CONCLUSION: The Flow Simulation over a Cylinder gives a clear insight into the effects of varying Inlet Velocity and thereby the Reynolds Number. The results depicted can be used to compare with the analytical solution and satisfy the correctness of the simulation.