Getting started with Flow Simulation in SolidWorks

Flow Simulation Through Pipe using SolidWorks

1. AIM : To run an internal pipe flow simulation in SolidWorks.

2. OBJECTIVE :

• To run an internal pipe flow 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.

3. INTRODUCTION :

3.1 FLUID: - A fluid is any substance that flows or deforms under applied shear stress. Or, The substances which have the tendency to flow is also called as fluid.

3.2 Fluid Flow Simulation: - Carrying out fluid flow simulation in a virtual environment is a better suited approach. This allows the engineers to model the fluid’s behavior at every stage in the process and accurately predict how it will react in an actual casting environment. In doing so, it greatly reduces the time it takes to create a working design, which can then be manufactured in the real world. Because of the work that has been done in the virtual world, the chances of this unit performing as excepted are greatly increased and the overall cost of development is substantially reduced.

3.3 Types of Fluid Flow :

• Laminar and Turbulent fluid flow : - This laminar fluid flow is defined as the type of flow in which the fluid particles move along well-defined paths or streamline and all the streamlines are straight and parallel.

Thus, the particles move in laminas or layers gliding smoothly over the adjacent layer. This type of fluid is also called as streamline flow or viscous flow.

This Turbulent fluid flow is defined as the type of flow in which the fluid particles move in a zig-zag way, the eddies formation takes place which is responsible for high energy loss.

For pipe flow, the type of flow is determined by a non-dimensional number called the Reynolds number.

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, vorticesand other flow instabilities.

3.4 Reynolds Number: - Reynolds number is a dimensionless value which is applied in fluid mechanics to represent whether the fluid flow in a duct or pat a body is steady or turbulent. This value is obtained by comparing the inertial force with the viscous force.

The Reynolds number is denoted by Re.

Reynolds number is given by,

`"Reynolds Number =" "Inertial force" /"Viscous force"`

The Reynolds number formula is expressed by,

`"Re = " ρuD/μ = uD/ν`

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) .

Reynolds number formula is used to determine the velocity, diameter and viscosity of the fluid.

The Kind of flow is based on the value of Re ,

1. If Re < 2000, the flow is called Laminar flow
2. If Re > 4000, the flow is called Turbulent flow
3. If 2000 < Re < 4000, the flow is called transition.

4. PROCEDURE :

For performing flow simulation inside pipe, we will need the 3D model of pipe.

So, first we need to design 3D model of pipe. And for designing any 3D model, we have to design 2D sketch of the model first, after that we can proceed for designing 3D model.

fig.1: 2D sketch of circular part of pipe

• All dimensions are in the unit system of MKS (i.e. meter, kilogram, seconds).
• Right plane is used here for 2D sketch of pipe.

Now going to extrude the circle to form a solid pipe structure. After that going to use “shell” option to make the solid pipe into a hollow pipe.

Dimensions taken for Pipe –

1. Outer Diameter = 0.05 m
2. Length = 1 m
3. Thickness = 0.001 m
4. Inner Diameter = 0.048 m

Now, going to sketch three vertical line probes in front plane at a distance of 0.95m, 0.90m, and 0.85m from the inlet circular part of pipe. These line probes will help us to visualize the flow inside pipe at different positions in a better way.

3D Model -

fig.2: 3D model of hollow pipe with line probes

As we have to perform a flow simulation so, we need to consider a fluid which will flow through the pipe for our flow simulation study.

Here, we are considering water for our flow simulation study.

5. CALCULATION :

Fluid characteristics –

Fluid used: Water

Dynamic viscosity of water (μ) = `8.90×10^(-4)`

Density of water (ρ) = `1000" kg/" "m" ^3`

As we know that,

`"Re = " ρuD/μ`

where,

Inner Diameter of pipe (D) = 0.048 m

Then,

for Re = 100	for Re = 1000	for Re = 10,000
we get, u = 0.00185 m/s	we get, u = 0.0185 m/s	we get, u = 0.185 m/s

Now, we will go to the flow simulation in SolidWorks.

And we will make pipe close both the ends by using “Create Lids” option under SolidWorks flow simulation. These Lids will make our pipe as fluid tight and it will help us to create the boundary conditions.

After creating Lids, we will now go to insert boundary conditions and we will assign boundary conditions as follows -

1. Inlet velocity at lid1 (inlet side of pipe)
2. Static pressure at lid2 (outlet side of pipe)
3. Real wall across the length of the pipe.

Now, going to provide mesh along X, Y and Z axes of pipe. This is an important thing with aspect for getting more accurate result and also in better visualization.

So, here assigning mesh from ‘global mesh’ along different axes as follows –

1. Along X-axis → 100
2. Along Y-axis → 20
3. Along Z-axis → 20

fig.3: Creating Mesh inside the pipe

After that, we will make cut plots across the line probes; this will give us a better visualization.

And completing all above steps, now we are ready to perform the Parametric Study. By doing parametric study, we will get results as plot for different inlet velocities of fluid (i.e. for different Reynolds Number) at different points inside the pipe (i.e. line probes).

6. RESULTS :

6.1 Study-1: Pipe flow simulation with inlet Reynolds number (Re) = 100 & flow speed (u) = 0.00185 m/s

a. for Line Probe at 95% -

b. for Line Probe at 90% -

c. for Line Probe at 85% -

Velocity comparison –

fig.4: Velocity comparison at different line probes

Normalizing the velocity profile by inlet velocity –

Normalized_Velocity comparison –

fig.5: Normalized_Velocity comparison at different line probes

fig.6: flow throughout the whole pipe (front view)

Simulation Video –

6.2 Study-2: Pipe flow simulation with inlet Reynolds number (Re) = 1000 & flow speed (u) = 0.0185 m/s

a. for Line Probe at 95% -

b. for Line Probe at 90% -

c. for Line Probe at 85% -

Velocity comparison –

fig.7: Velocity comparison at different line probes

Normalizing the velocity profile by inlet velocity –

Normalized_Velocity comparison –

fig.8: Normalized_Velocity comparison at different line probes

fig.9: flow throughout the whole pipe (front view)

Simulation Video –

6.3 Study-3: Pipe flow simulation with inlet Reynolds number (Re) = 10,000 & flow speed (u) = 0.185 m/s

a. for Line Probe at 95% -

b. for Line Probe at 90% -

c. for Line Probe at 85% -

Velocity comparison –

fig.10: Velocity comparison at different line probes

Normalizing the velocity profile by inlet velocity –

Normalized_Velocity comparison –

fig.11: Normalized_Velocity comparison at different line probes

fig.12: flow throughout the whole pipe (front view)

Simulation Video –

Drive link for 3D models, Results in Excel sheet :-

https://drive.google.com/file/d/1c2ojP5Dx42KJPrwyEDlwk4tOiDeTpcWR/view?usp=sharing

7. OBSERVATIONS & CONCLUSIONS :

1. Velocity increases as we move towards center of pipe from wall due to more shear stress between the layers of fluid at center.
2. As the line probes at 95%, 90%, and 85% of pipe length are very close to each other that’s why the velocity profile does not change much.
3. Increasing the value of Reynolds number, the pattern of flow changes as well as flow changes into turbulent from laminar flow.
4. With increase in Reynolds number, velocity gets more uniform.
5. Increasing the number of mesh, gives more accurate result and allows better visualization.