Getting Started with flow simulation in SolidWorks

Getting Started with flow simulation in SolidWorks

Objective:

To plot the velocity profiles for the 3 different Reynold numbers placing the probe at 85% ,90% and 95% of the length of the Pipe.

Introduction:

The fluid velocity in a pipe changes from zero at the surface because of the no-slip condition to a maximum at the pipe center. In fluid flow, it is convenient to work with an average velocity Vavg, which remains constant in incompressible flow when the cross-sectional area of the pipe is constant (Fig. 8–2). The average velocity in heating and cooling applications may change somewhat because of changes in density with temperature. But, in practice, we evaluate the fluid properties at some average temperature and treat them as constants. The convenience of working with constant properties usually more than justifies the slight loss in accuracy.

Average velocity Vavg is defined as the average speed through a cross section. For fully developed laminar pipe flow, Vavg is half of maximum velocity

The development of the velocity boundary layer in a pipe. (The developed average velocity profile is parabolic in laminar flow, as shown, but somewhat flatter or fuller in turbulent flow.)

Solution Procedure:

For Reynolds No = 100

Length of the pipe = 1 m

Diameter of the Pipe = 0.04m

Shell is created at two faces with the dimensions 0.001m

Inlet Velocity =0.0152m/s

Fluid is air

Dynamic Viscosity of air at 18*C is 1.825*10^-5 Kg/m-s

Outlet Pressure = Environmental pressure

Density of air = 1.225Kg/m-s

Pressure =Atm pressure

Pipe Wall =Real Wall

Temperature =293K

Steps followed:

• Create a new part model
• Make a circle 0.01m diameter and extrude it to 0.1m to make it as a cylinder.
• Select shell, then select both face side of the cylinder and 1mm as thickness by making a pipe.
• Create a new sketch along the length of the pipe and create a vertical line at 85%,90% and 95% of the length
• Go to flow simulation and select create Lid command and select end faces of the pipe to make a closed airtight for CFD simulation.
• Click on New in flow simulation toolbar. Right click on input data on flow simulation tree and select general setting.
• In fluids,select air in gas as project fluid,flow type as laminar for first two cases and turbulent for the third case.
• Right click on boundary condition and given three boundary conditions inlet velocity , outlet static pressure and real wall which we will select the inner wall of the pipe.
• Right click on global mesh and select edit definitions,change the mesh manually in X-direction as 20,Y-direction as 20 and Z-direction as 80.
• Right Click on XY plot for velocity in notmal to the plane direction(z-plane) and select insert and select the 85% line sketch. Similarly, make XY plot for 90% and 95%.
• Right Click on cut plots and make cut plot at different sections in the probe length.

Modelled Part Meshed model

Computational Domain

Boundary Conditions:

1. The inlet velocity is given at the one end of the pipe
2. The static pressure is given at the other end.
3. The real wall is the wall of the pipe
4. Periodic B.C - Because of axisymmetric the fluid should be flowing, so we are creating interface. If error comes Because of wall, then we should change from wall to axis so that the fluid will flow whereas in wall it will consider as the solid cylinder where the fluid will not flow.

Results and Explanation:

• From the below graphs and images , it is observed that only slight difference in velocity curve at 85%,90% and 95% length of the pipe in each cases of Reynolds no.
• As we know that, pipe flow starts to become turbulent after the Reynolds no 2000, if we see the cut-sections at Reynolds no 10000 as compared to 100 and 1000, we can see that the velocities are distorted because the flow is turbulent.
• As compared to the 85% , the 95% velocity profile is more parabolic because towards the outlet the profile is fully developed and it is fully parabolic. On the other words, at inlet the profile is started to develop so the profile is not fully parabolic.
• Normalizing the velocity profile to inlet velocity

u/u₀ = 1 – (r²/R²)

Where r=0 to R = maximum radius

Case 1: For Reynolds No -100

Inlet Velocity = 0.0152m/s

• Placing probe at 85% of length of the pipe:

• Placing probe at 90% of length of the pipe:

• Placing probe at 95% of length of the pipe:

• Comparison of velocity profiles:

Case 2: For Reynolds No -1000

Inlet Velocity = 0. 152m/s

• Placing probe at 85% of length of the pipe:

• Placing probe at 90% of length of the pipe:

• Placing probe at 95% of length of the pipe:

• Comparison of all velocity profiles

Case 3: For Reynolds No -10000

Inlet Velocity = 1.52m/s

• Placing probe at 85% of length of the pipe:

• Placing probe at 90% of length of the pipe:

• Placing probe at 95% of length of the pipe:

• Comparison of all velocity profiles:

Drive Link: (CAD models)

https://drive.google.com/drive/folders/1XjtLYCKgjEnMD0FqBJtkThywER_2yr3_?usp=sharing

References:

• Fluid mechanics by Cengel and Cimbla, Ebook
• https://en.wikipedia.org/wiki/Pipe_flow#:~:text=Pipe%20flow%2C%20a%20branch%20of,conduit%20is%20open%20channel%20flow.&text=Energy%20in%20pipe%20flow%20is,defined%20by%20the%20Bernoulli%20equation.