Pipe flow simulation using Solidworks

Objective- To run a 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.

Inputs :

Diameter of pipe = 0.018m

Length of the pipe= 0.3m

Air density = 1.2047(kg/m3)

Dynamic viscosity of air (at 20 degree celcius & 1 atm pressure)1.825⋅10^(-5) (N-s/m^2)

Theory- Reynolds Number
The Reynolds number is the ratio of inertial forces to viscous forces. The Reynolds number is a dimensionless number used to categorize the fluids systems in which the effect of viscosity is important in controlling the velocities or the flow pattern of a fluid. Mathematically, the Reynolds number, Re, is defined as

Re=(ρ⋅v⋅d)/μ

rho = density

v = velocity

d = diameter

mu= viscocity

Flow-through pipes are classified into three main flow regimes.

1.Laminar flow – R < 2000

2.Critical flow/Transition flow – R > 2000 and R < 4000

3.Turbulent flow – R > 4000

R value of 2100 is used as the limit of laminar flow.

Calculation of inlet velocity

Reynolds number = (rho x Velocity x D)/Dynamic visosity

By applying the above inputs and formula for reynolds number, (Ra=100,1000 & 10000)

We get,

Velocity for (Re = 100) = 0.09445 m/s

Velocity for (Re = 1000) = 0.9445 m/s

Velocity for (Re = 10000) = 9.445 m/s

Procedure

Steps to be taken for simulation:
1)Create new part model.
2)Make circle of 18mm dia and extrude it to 300 mm.
3)Select shell, then select both face side of the cylnder and 1mm as thickness. 
4)Create new sketch along length of the pipe & create a vertical line at 85% of the length and similarly for 90% ard 95% of the length.
5)Go to Flow Simulatlon, select create lid command & select end faces of the pipe.
6)Click on new in flow simulation toolbar. Right click on input data on flow simulation tree, and select gerneral setting.
7)In Fluids, select air in gas, flow type as Laminar for first two cases and turbulent for third case and in initial conditions, temperature as 293.2 K, pressure as 101325 Pa and velocity as 0m/s.
8)Right click on boundary conditions and select insert boundary conditions. The boundary condition for inflow is the three inlet velocity at three different cases on inlet of the pipe. The boundary conditicn for wall is real wall and select inner wall of the pipe.
9)The first boundary condition for out-flow, select static pressure of 101325 Pa
10)Right click on Gloal Mesh and select edit definitions, change mesh manually, in X-direction 10,  Y-direction 10, in Z-direction 50.
11)Right click on XY plot for velocity in normal to the plane direction (Z-direction) and select insert then select the 85% line sketch. Similarly, make XY plot tor 90% and 95% and similarly right click on cut plot for velocity in XY plane at distances of 85% 90% & 95% of length and than Run.
12)Right click on project name and select new parametric study. Then select inlet velocity in input variables than, select all XY plots & cut plots. Go to scenario tab and select design point 1 and copy paste it two more times. Change mesh in design point 2 and 3 by doubling them & run.
13)Now after case 1 create new project & change the inlet velocity and click on run and than similarly run a new parametric study for the two velocities.

Output -

Case 1: Re = 100

1) At 85% of length

A) Cutplot at 85% of length

• Design point 1

• Design point 2

• Design point 3

• B) XY plot

2) At 90% of length

A) Cutplot at 90% of length

• Design point 1

• Design point 2

• Design point 3

• B) XY plot

3) At 95% of length

A) Cutplot

• Design point 1

• Design point 2

• Design point 3

B) XY plot

Case 2: Re = 1000

1) At 85% of length

A) Cutplot

• Design point 1

• Design point 2

• Design point 3

B) XY plot

2) At 90% of length

A) Cutplot

• Design point 1

• Design point 2

• Design point 3

B) XY plot

2) At 95% of length

A) Cutplot

• Design point 1

• Design point 2

• Design point 3

B) XY plot

Case 3: Re = 10000

1) At 85% of length

A) Cutplot

• Design point 1

• Design point 2

• Design point 3

B) XY plot

2) At 90% of length

A) Cutplot

• Design point 1

• Design point 2

• Design point 3

B) XY plot

3) At 95% of length

A) Cutplot

• Design point 1

• Design point 2

• Design point 3

B) XY plot

• Comparison of velocity in XY plot at 85% of length of design point 3 with Re = 100/1000/10000

• Comparison of velocity in XY plot at 90% of length of design point 3 with Re = 100/1000/10000

• Comparison of velocity in XY plot at 95% of length of design point 3 with Re = 100/1000/10000

Result- As from the above we can say that the area under the curve of Re=10000 (turbulent) is maximum in all cases. And we conclude that the area increases if velocity increases. So,Reynolds number increases as turbulence increases.