Pipe flow Simulation with line probes in SolidWorks

Aim: To do the simulation of pipe flow using line probes in SolidWorks Flow Simulation

Objective:

• Run a pipe flow simulation with an inlet Reynolds number of 100,1000 and 10000.
• For each of these cases do the following:

1. Place line probes at 95%, 90% and 85% of the pipe length.
2. Compare the normalized velocity profile at each of these locations.
3. Normalize the velocity profile by the inlet velocity.

Introduction:

Laminar flow:

• Laminar flow occurs when the fluid flows in infinitesimal parallel layers with no disruption between them.
• In Laminar flows, fluid layers slide in parallel with no eddies, swirls or currents normal to the flow itself.

                                                          Fig. Laminar flow in closed pipe

Turbulent flow:

• In fluid dynamics, a turbulent means irregular flows in which eddies, swirls, and other flow instabilities occur.
• Turbulence is commonly observed in everyday phenomena such as fast flowing rivers, smoke from chimney, etc.

                                                          Fig. Turbulent flow in closed pipe

Reynold’s number:

• The Reynold’s number (Re) is a dimensionless number expressing the ratio between inertial force and viscous force.
• The Reynold’s number is a mathematically defined as:

• At low values of Re, the flow is Laminar. But when Re exceeds a certain threshold, semi-developed turbulence occurs in the flow, this regime is referred to as Transition regime and occurs for a certain range of the Reynold’s number.
• Finally, over a certain value of Re, the flow becomes fully

Viscosity:

• The resistance of a fluid to flow when subjected to a force is called Viscosity.

Dynamic Viscosity

• The unit of measurement of Dynamic Viscosity is Pa s or N s/m²
• Dynamic Viscosity is also known as Absolute viscosity.

Kinematic Viscosity

• The unit of measurement of Kinematic Viscosity is m²/s
• Kinematic Viscosity is also known as Diffusivity of Momentum.

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Specification of problem:

Diameter of pipe = 0.04m

Thickness of pipe = 0.001m

At 25° C

        µ = 0.00089 Pa s or 0.00089 N s/m²

  = 1000 kg/m³

Length of pipe L = 1m

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Calculations:

For Reynold’s number Re =100

Therefore,

     V = 0.00223 m/s ------------------------------(CASE 1)

Similarly, for Re = 1000

      V = 0.0223 m/s------------------------------- (CASE 2)

And       for, Re = 10000

      V = 0.223 m/s--------------------------------- (CASE 3)

Procedure for Simulation for all the 3 cases:

• Modelling of pipe in SolidWorks

• Place the line probes at 85%, 90% and 95% of the pipe length by using the sketch command.
• Go to the Flow Simulation from SolidWorks Add-ins

• Create a new project in Flow Simulation

• Create the lids at the end faces of the pipe for watertight enclosed volume which is mandatory for CFD analysis.

• Now form general settings set the analysis type as shown in the following figure:

• In this project we will consider water as fluid for all the 3 cases and the flow characteristic be Laminar and Turbulent.

• Wall Condition is set as below:

• Initial condition parameters are set as below:

• Set boundary conditions at inlet, outlet and inner wall of the pipe.
• Insert XY plots for all the 3 cases
• Insert Cut plots for all the 3 cases

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Case No: 1 (Re= 100)

For inlet boundary condition:

Inlet velocity = 0.0023 m/s

For outlet boundary condition:

Static pressure= 101325 Pa

Temperature = 293.2 K

Third Boundary condition:

Real wall

Results for Case No : 1 (Re = 100)

                       Cut plot for 85% pipe length   

                Cut plot for 90% of pipe length                                                    Cut plot at 95% of pipe length

Velocity plots for Case : 1

                                                        Fig. Shows the Velocity plot for Case:1 Re=100, v = 0.0023 m/s

                                                            Fig. Shows the Velocity plot for Case:1 Re=100, v = 0.023 m/s

                                                              Fig. Shows the Velocity plot for Case : 1 Re = 100, v = 0.23 m/s

Velocity Comparison plot for Case:1

                                                           Fig. Shows the Comparison of velocity plots for Case:1

Case : 2  (Re =1000)

                    Cut plot at 85% of pipe length   

                Cut plot at 90% of pipe length                                                  Cut plot at 95% of pipe length                               

Velocity Plots for Case : 2

                                             Fig. Shows the Velocity plot for Case:2 at Re= 1000 and v=0.0023 m/s

                                                      Fig. Shows the Velocity plot for Case:2 at Re= 1000 and v=0.023 m/s

                                             Fig. Shows the Velocity plot for Case:2 at Re= 1000 and v=0.23 m/s

                                                            Fig. Shows the Comparison of velocity plots for Case:2

Case : 3 (Re =10000)

               Cut plot at 85% of pipe length   

                   Cutplot at 90% of pipe length                                                 Cut plot at 95% of pipe length

Velocity Plots for Case:3

                                                              Fig. Shows the Velocity plot for Case:3 at Re= 10000 and v=0.0023 m/s

                                                              Fig. Shows the Velocity plot for Case:3 at Re= 10000 and v=0.023 m/s

                                                              Fig. Shows the Velocity plot for Case:3 at Re= 10000 and v=0.23 m/s

Velocity Comparison plot for Case : 3

                                                                   Fig. Shows the Comparison of velocity plots for Case:3 

Conclusion:

• We can observe from the above plots that for Case:1 the velocity profile is parabolic in nature.
• The flow is laminar in Case:1 and in Case:2) as the Reynold’s number is lower in both the cases (i.e., Case:1 = 100 and Case:2 = 1000)
• As the Reynold’s number is high Re= 10000 so the flow is turbulent, the Velocity plot of Case:3 at different velocities not parabolic.
• We can finally conclude that as the Reynold’s number increases, the flow changes from laminar to turbulent.