Pipe Flow Simulation using Solidworks

Aim:- Pipe Flow Simulation using Solidworks

Objective:-

To study simulation with an inlet Reynolds number of 100, 1000, and 10,000.

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:-

Pipe flow, a branch of hydraulics and fluid mechanics, is a type of liquid flow within a closed conduit (conduit in the sense of a means of containment). The other type of flow within a conduit is open channel flow. These two types of flow are similar in many ways but differ in one important aspect. Pipe flow does not have a free surface which is found in open-channel flow. Pipe flow, being confined within a closed conduit, does not exert direct atmospheric pressure but does exert hydraulic pressure on the conduit.

Reynolds number

The Reynolds number (Re) is an important dimensionless quantity in fluid mechanics used to help predict flow patterns in different fluid flow situations. At low Reynolds numbers, flows tend to be dominated by laminar (sheet-like) flow, while at high Reynolds numbers turbulence results from differences in the fluid's speed and direction, which may sometimes intersect or even move counter to the overall direction of the flow (eddy currents). These eddy currents begin to churn the flow, using up energy in the process, which for liquids increases the chances of cavitation. The Reynolds number has wide applications, ranging from liquid flow in a pipe to the passage of air over an aircraft wing. It is used to predict the transition from laminar to turbulent flow and is used in the scaling of similar but different-sized flow situations, such as between an aircraft model in a wind tunnel and the full-size version. The predictions of the onset of turbulence and the ability to calculate scaling effects can be used to help predict fluid behavior on a larger scale, such as in local or global air or water movement and thereby the associated meteorological and climatological effects.

With respect to laminar and turbulent flow regimes:

• laminar flow occurs at low Reynolds numbers, where viscous forces are dominant, and is characterized by smooth, constant fluid motion;
• turbulent flow occurs at high Reynolds numbers and is dominated by inertial forces, which tend to produce chaotic eddies, vortices, and other flow instabilities.

The Reynolds number is defined as

where:

• ρ is the density of the fluid (SI units: kg/m³)
• u is the flow speed (m/s)
• D is the diameter of the tube (m)
• μ is the dynamic viscosity of the fluid (Pa·s or N·s/m² or kg/(m·s))
• ν is the kinematic viscosity of the fluid (m²/s).

In general, if Re < 2300, the fluid experiences laminar flow. If Re > 4000, its flow is turbulent. If the value of Reynolds number lies in between these two boundaries, it is a case of transitional flow.

Laminar Flow

The primary characteristic of laminar flow is a streamlined flow, lacking any swirls or cross currents. If one imagines different layers of fluid, divided into rows/cylinders with varying radii, the layers of the fluid wouldn’t mix in any manner. The fluid would flow without interference or disturbance, and the path of the flow wouldn’t have any swirls or cross currents.

The layers or “tubes” of the fluid would still flow at different speeds, even though they wouldn’t cross or intersect. The central, innermost layer would have the fastest flow speed while the outer layers would have a much slower flow speed (sometimes hardly moving at all). In general, the velocity of a fluid with laminar flow is extremely low.

Real-world applications for laminar flows include any liquid flowing through a tube. This is because the dimensions of the tube or pipe stay constant and as a result, the volume of the fluid doesn’t have a chance to change. The laminar flow of air over the wing of an airplane is an important consideration when designing planes. The wings of planes are often designed to make sure air flows over them in a laminar way, minimizing turbulence.

Turbulent Flow

Turbulent flow is characterized by the chaotic and rough movement of particles through a region. Imagining layers of fluid again, you can think of the various layers mixing with one another, with a heavy amount of friction existing between the boundaries of the different layers. Molecules are thrown around in an irregular fashion, and whirlpools and waves can easily be found within the flow.

Fluids that are in turbulent flow have a substantial amount of kinetic energy within them. As long as this energy persists, the flow will continue to be turbulent and irregular. Once the energy is used up, the flow transitions to a laminar state. The velocity of a turbulent fluid is typically high, equalizing as it transitions to a laminar flow state.

An easy to grasp example of laminar flow is the waves and currents found in the ocean, which collide and mix with one another. The turbulent nature of the water, and of many fluids, is driven by convection. Convection makes many different fluids, like the air itself, turbulent.

Procedure:-

1. A new part model created using a circle of diameter 0.052 m and extruded it to 1 m.
2. Selected shell option in the features and selected the 2 faces of the pipe and provided a thickness of 0.001m, to make the pipe hollow.
3. Now line probes at 85%, 90%, and 95% are drawn using a new sketch for each line in top plane.
4. Now using flow simulation lid command is selected and drawn the lids on 2 faces of the pipe to make it watertight which is necessary to perform flow simulation.
5. Created a new project under the flow simulation, and specified the input data by defining the general settings by selecting the type of fluid and the flow type.
6. Now define the boundary conditions by clicking on insert boundary conditions and specify the inlet boundary condition as inlet velocity, outlet boundary condition as static pressure and temperature, and then specify the real wall boundary conditions.
7. Create a manual/automatic basic mesh, and define the X-Y plots and cut plots for the velocity at each location and compare the velocity between the locations.
8. Then start a new parametric study, select the inlet face velocity as an input variable, and select all X-Y plots and cut plots as output variables.
9. Now in the scenario tab copy the first set and paste it two more times changing the face velocity variable. Finally, run the parametric study.

Specifications and Calculations:-

The external diameter of pipe = 0.052 m

The internal diameter of pipe = 0.050 m

The thickness of pipe = 0.001 m

The length of pipe = 1 m

Mesh index = 4

At STP( temperature=0 degree celcius/ 273.15k and pressure = 101325 pascal):

The density of water = 998.207 kg/m^3

Viscosity of water = 0.001792 kg/m.s

Using Reynolds formula, velocity is calculated.

For Re=100, Velocity = 0.00359 m/s

For Re=1000, Velocity = 0.0359 m/s

For Re=10000, Velocity = 0.359 m/s

Descriptions of study:-

Pipe model

Line probes at 85%, 90% and 95% of the length of pipe at the exit end

Input variables for Parametric Study

Output variables for Parametric Study

The scenario for Parametric Study

Study 1- Pipe flow simulation at line probe 85%

Cut plot at line probe 85%(0.15m from the face2) and at velocity = 0.00359 m/s

Cut plot at line probe 85%(0.15m from the face2) and at velocity = 0.0359 m/s

Cut plot at line probe 85%(0.15m from the face2) and at velocity = 0.359 m/s

Velocity plot at line probe 85%(0.15m from the face2)

Study 2- Pipe flow simulation at line probe 90%

Cut plot at line probe 90%(0.10m from the face2) and at velocity = 0.00359 m/s

Cut plot at line probe 90%(0.10m from the face2) and at velocity = 0.0359 m/s

Cut plot at line probe 90%(0.10m from the face2) and at velocity = 0.359 m/s

Velocity plot at line probe 90%(0.10m from the face2)

Study 3- Pipe flow simulation at line probe 95%

Cut plot at line probe 95%(0.05m from the face2) and at velocity = 0.00359 m/s

Cut plot at line probe 95%(0.05m from the face2) and at velocity = 0.0359 m/s

Cut plot at line probe 95%(0.05m from the face2) and at velocity = 0.359 m/s

Velocity plot at line probe 95%(0.05m from the face2)

Velocity Comparison Plot for each line probe

Design point 1 is for 0.00359 m/s velocity

Design point 2 is for 0.0359 m/s velocity

Design point 3 is for 0.359 m/s velocity

Sketch 3 is line probe at 85% of the length of the pipe

Sketch 4 is line probe at 90% of the length of the pipe

Sketch 5 is line probe at 95% of the length of the pipe

Observations:-

Maximum velocity is at the center(along the longitudinal axis of the pipe) and minimum velocity is around the inner cylindrical walls of the pipe.

For cut plot at 85% of the length of the pipe:-

Design point 1 - For inlet velocity of water 0.00359 m/s:

Maximum velocity is 0.007 m/s

Minimum velocity is 0.00095 m/s

Design point 2 - For inlet velocity of water 0.0359 m/s

Maximum velocity is 0.055 m/s

Minimum velocity is 0.011 m/s

Design point 3 - For inlet velocity of water 0.359 m/s

Maximum velocity is 0.420 m/s

Minimum velocity is 0.272 m/s

For cut plot at 90% of the length of the pipe:-

Design point 1 - For inlet velocity of water 0.00359 m/s

Maximum velocity is 0.007 m/s

Minimum velocity is 0.00095 m/s

Design point 2 - For inlet velocity of water 0.0359 m/s

Maximum velocity is 0.055 m/s

Minimum velocity is 0.011 m/s

Design point 3 - For inlet velocity of water 0.359 m/s

Maximum velocity is 0.422 m/s

Minimum velocity is 0.274 m/s

For cut plot at 95% of the length of the pipe:-

Design point 1 - For inlet velocity of water 0.00359 m/s

Maximum velocity is 0.007 m/s

Minimum velocity is 0.00094 m/s

Design point 2 - For inlet velocity of water 0.0359 m/s

Maximum velocity is 0.055 m/s

Minimum velocity is 0.012 m/s

Design point 3 - For inlet velocity of water 0.359 m/s

Maximum velocity is 0.424 m/s

Minimum velocity is 0.275 m/s

Tabular Data:

Sr. no.	Reynolds number	Velocity(m/s)	%age of length	Velocity at (m/s)
				center(max)	wall(min)
1	100	0.00359	85
a	100	0.00359	85	0.007	0.00095
b	100	0.00359	85	0.007	0.00095
c	100	0.00359	85	0.007	0.00094
2	1000	0.0359	90
a	1000	0.0359	90	0.055	0.011
b	1000	0.0359	90	0.055	0.011
c	1000	0.0359	90	0.055	0.012
3	10000	0.359	95
a	10000	0.359	95	0.420	0.272
b	10000	0.359	95	0.422	0.274
c	10000	0.359	95	0.424	0.275

Conclusion:-

1. By increasing the Reynolds number by 10 times, the maximum velocity at the center increases by 7.85 times in the second case and by 7.67 times in the third case. That is for Re=100, maximum velocity is 0.007m/s, for Re=1000, maximum velocity is 0.055m/s and for Re=10000, maximum velocity is 0.422m/s.
2. By increasing the Reynolds number by 10 times, the minimum velocity at the wall increases by 11.58 times in the second case and by 24.9 times in the third case. That is for Re=100, minimum velocity is 0.00095m/s, for Re=1000, minimum velocity is 0.011m/s and for Re=10000, minimum velocity is 0.274m/s.
3. As the Reynolds number increases, the difference between the maximum velocity and the minimum velocity reduces. For Re=100, the difference between the maximum and the minimum velocity is of 7.37 times; For Re=1000, the difference between the maximum and the minimum velocity is of 5 times and For Re=10000, the difference between the maximum and the minimum velocity is of 1.54 times.
4. The outlet velocity for each line probes at 85%,90%, and 95% of the length of the pipe is almost the same.
5. The outlet velocity around the wall is minimum due to the viscosity of the fluid and the formation of the boundary layer.
6. Since the pipe is horizontal, the potential energy is unchanged due to which the increase in kinetic energy is at the cost of pressure energy. Therefore, the velocity of the fluid increases while flowing through a conduit, and its pressure drops.

Google drive link - https://drive.google.com/drive/folders/1wBWIoUIYp0bmuGIm-iF5FUHxplFhMIPp?usp=sharing

Reference:-

https://en.wikipedia.org/wiki/Pipe_flow

https://en.wikipedia.org/wiki/Reynolds_number