Pipe Flow Simulation

AIM

To run a Pipe Flow Simulation.

OBJECTIVES

• To run a Pipe Flow Simulation in SOLIDWORKS for inlet Reynolds Number of 100,1000 and 10000.
• To place line probes at 85%, 90% and 95% of the pipe length and

1. Compare the normalised velocity profile at the locations
2. Normalise the velocity profile by inlet velocity

INTRODUCTION

Computational Fluid Dynamics or CFD is a technique that deals with the solution of fluid flow fields through numerical analysis. SOLIDWORKS Flow Simulation is a CFD software designed for the everyday SOLIDWORKS user and analyst. It provides dynamic feedback on the fluid flow and Thermal performance of their products. With Parametric optimization capabilities, users can automate the design and analysis process to discover the best iteration of their design within the familiar SOLIDWORKS environment.

The pipe networks are common in any engineering industry. It is important to know the development of a flow at the pipe entrance and pressure drop taking place along the pipe length. The purpose of this simulation is to illustrate the setup and solution of a flow in a pipe. The flow of fluids in a pipe is widely studied fluid mechanics problem. The correlations for entry length and pressure drop are available in terms of flow Reynolds number.

THEORY

Geometry:

CAD model of a hollow cylinder or pipe having the dimension as follows:

External diameter of pipe=0.05 m

Internal diameter of pipe=0.048 m

Length of pipe=1 m

Thickness of pipe=0.001 m

Boundary condition:

Inlet velocity =

1. 0.00185 m/s when R=100
2. 0.0185 m/s when R=1000
3. 0.185 m/s when R=10,000

Static pressure = 101325 Pa

Temperature = 293.2 K

Wall type: Real wall

Reynolds number equation:

`R_e=(rhovD)/(mu)`

where:

`R_e` is the Reynolds number, which is unitless

ρ is the fluid density in kilograms-per-cubic-meter (kg/m^3)

v is the velocity in meters-per-second (m/s)

D is the diameter of the pipe in meters (m)

μ is the viscosity of the fluid in Pascal-seconds (Pa⋅s)

Fluid characteristics

Fluid used: water

Dynamic viscosity: 8.9×10^-4Pa.s

Density of water: 1000 kg/m^3

So, from the equation for Reynolds number, `v=(muR_e)/(rhoD)`

Velocity at different Reynolds numbers:

v=0.001854 m/s; `R_e`=100

v=0.01854 m/s; `R_e`=1000

v=0.1854 m/s; `R_e`=10,000

CASE SETUP

1. The model is created using the following dimensions mentioned above.
2. Then probes are created at 85%, 90% and 95% of the pipe length.
3. Then using the ‘Flow Simulation’ option lids are created at open ends. These lids help us to define the boundary condition.
4. Now the ‘Wizard’ option is selected in the Flow simulation feature and the necessary conditions are set up.
5. The Flow type is set to Internal and Fluid was chosen as Water. All other conditions are set as default.
6. This will result in the creation of the required computational domain.
7. After this, the ‘Boundary Conditions’ are set using the ‘Insert Boundary Condition’ option. The boundary conditions: Inlet Velocity at Lid1, Static Pressure at Lid2 and Real wall across the length of the pipe.
8. The Global Mesh level is chosen to be 4.
9. XY plots are made using the line probes to compare the velocity profiles.Cut Plots are also made across the probes.
10. After this a Parametric study is made. The Input parameter is selected as the Inlet Velocity, Output parameters are the Cut Plots and XY plots.
11. Three different scenarios are set up for the Reynolds number 100,1000 and 10000 by changing the Inlet Velocity.
12. The Parametric Study was Run and the results were obtained.

RESULTS

For Re=100 and v=0.001854 m/s

At 85% of pipe length

At 90% of pipe length

At 95% of pipe length

For Re=1000 and v=0.01854 m/s

At 85% of pipe length

At 90% of pipe length

At 95% of pipe length

For Re=10000 and v=0.1854 m/s

At 85% of pipe length

At 90% of pipe length

At 95% of pipe length

Variation of Velocity profile with Reynolds number

At 85% of pipe length

At 90% of pipe length

At 95% of pipe length

OBSERVATIONS

• It was observed that the contours of velocity has very less variation as the Reynolds number increases.
• Also as the fluid moves forward, velocity gradually forms a parabolic profile.

CONCLUSION

Therefore, the Pipe Flow simulation is successfully completed and the results are studied.