Pipe Steady Flow Analysis using SolidWorks Flow Simulation

Aim: To simulate a steady flow through a pipe for Reynolds number of 100, 1000 and 10000

Objectives:

1. To find the velocity distribution along the cross-section at 95%, 90%, and 85% of the pipe length.
2. Perform a Parametric Study dependent on the inlet velocity or in other words, the Reynolds number.

Theory:

The Reynolds number in fluid mechanics is a unitless number defined by the ratio of inertial forces to viscous forces. This number is characterized by the density of the fluid `rho` in kg/m^3, the flow speed u in m/s, the diameter of the tube D in m, and the dynamic viscosity `mu` of the fluid in Pa-s.

Re = `(rho * u*D)/mu`

There are two types of flows in fluid mechanics, namely laminar and turbulent. Laminar flow occurs at low Reynolds number (typically < 2300) and turbulent flow takes place at high Reynolds number (typically > 2900). Reynolds number between 2300 and 2900 indicates the transition of the flow type from laminar to turbulent.

Problem Specifications:

Pipe Internal Diameter: 0.038 m

Pipe Length: 1 m

Fluid Material: Water

Density: 1000 kg/m^3

Viscosity: 8.94e-4 Pa.s

Reynolds number	100	1000	10000
Inlet Velocity (m/s)	0.00234	0.0234	0.234

Outlet Pressure: 1 atm

Problem Solving Methodology:

Flow-through a pipe is simulated using SolidWorks Flow Simulation for three different inlet velocities. Lids were created at the ends of the pipe indicating a closed domain required for analysis in the software. Three Boundary Conditions were provided, namely the inlet velocity, the outlet pressure, and the pipe wall boundary. The type of flow selected was 'Laminar and turbulent'.

A parametric study was performed to get the results at different pipe cross-sections and a velocity comparison is done to find the difference in the velocities at different cross-sections. Cut Plots and XY Plots were the features used to post-process and display the results.

Geometry snapshot with mesh:

Mesh size: 20 x 20 cross-section and 50 divisions in length.

Results:

Velocity output at 95% of the pipe length:

• Inlet Velocity = 0.00234 m/s

• Inlet Velocity = 0.0234 m/s

• Inlet Velocity = 0.234 m/s

• Velocity comparison at 95% of the pipe length

Velocity output at 90% of the pipe length:

• Inlet Velocity = 0.00234 m/s

• Inlet Velocity = 0.0234 m/s

• Inlet Velocity = 0.234 m/s

• Velocity comparison at 90% of the pipe length:

Velocity output at 85% of the pipe length:

• Inlet Velocity = 0.00234 m/s

• Inlet Velocity = 0.0234 m/s

• Inlet Velocity = 0.234 m/s

• Velocity comparison at 85% of the pipe length:

Conclusion:

The output velocity at respective cross-sections is not significantly changed and almost remains the same. This indicates that the flow has already reached a state known as a Fully Developed Flow where the velocity profile does not change in the left-over length. This Fully Developed Flow state is obtained before 85% of the length (0.85m) of the total pipe length.