PIPE FLOW SIMULATION
1.AIM :
RUN A PIPE FLOW SIMULATION WITH VARIOUS INLET REYNOLDS NUMBER
2.OBJECTIVE :
- To perform flow simulation on a pipe using Solidworks flow simulation.
- To perform the flow simulation for an inlet Reynolds number of 100,1000 and 10,000.
- To study the normalized velocity profile at 95%, 90% and 85% of the pipe length for each reynolds no value.
3. INTRODUCTION :
Flow simulation through a pipe can be performed through computational fluid dynamics (CFD), a powerful and convinient tool to perform CFD is Solidworks flow simulation.
Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to analyze and solve problems that involve fluid flows. Computers are used to perform the calculations required to simulate the free stream flow of the fluid, and the interaction of the fluid with surfaces defined by boundary conditions.
In simple words to perform CFD following steps are performed in order:-
- A computational model is made using computer aided designing and the domain of fluid is extracted.
- Further the domain is divided into discrete cells called mesh.
- Next the Boundary conditions are defined, which is specifying the fluid behaviour and properties at all bounding surfaces of the fluid domain.
- Next the calculations are performed and the equations are solved iteratively till the convergence is acheived.
- Finally the analysis and visualization of the calculations performed can be seen.
The flow inside a pipe can be Laminar, turbulent or transistional, this can be determined with the help of Reynolds number.
The Reynolds number is the ratio of inertial forces to viscous forces within a fluid which is subjected to relative internal movement due to different fluid velocities.
`"Reynolds number, Re "= "inertia force"/"viscous force" = (ρ V D)/µ`
Where, ρ is mass density
V is average velocity of flow
D is diameter of pipe
µ is dynamic viscosity of flowing fluid
Based on the values of Reynold’s number (Re), different flows are classified as :
- Re<2000 - Laminar flow
- Re>4000 - Turbulent flow
- 2000< Re < 4000 - Transitonal flow
Here the flow simulation inside a pipe is performed for 3 different inlet Reynolds number which are 100,1000 and 10,000.
4.CALCULATION :
INPUT DATA-
Outer Diameter of Pipe,D = 20 mm = 0.02m
Thickness of Pipe = 2 mm = 0.002m
Length of Pipe = 1000mm = 1m
Fluid = Water
Density of Water = 1000Kg/m^3
Consider Outlet Pressure & Temperature :- 101325 Pa, 293K
`Re = (ρ* V* D)/µ`
We know that
Kinematic viscosity, `nu = mu/rho`
`=> Re = (V* D)/nu`
Kinematic Viscosity of Water at 293K, `nu = 1.004" x "10^-6 " m"^2"/s"`
For Re=100
`V = (Re*nu)/D`
`V = [100*1.004*10^-6]/0.02`
`V= 0.00502 " m/s"`
Similarly calculating for Re = 1000 and 10000
| Reynolds Number (Re) | Velocity, V (m/s) |
| 100 | 0.00502 |
| 1000 | 0.0502 |
| 10000 | 0.502 |
5.PROCEDURE :
1) First the model of a pipe with dimensions is created using Solidworks
- Outer Diameter of Pipe = 24 mm = 0.024 m
- Thickness of Pipe = 2 mm = 0.002 m
- Length of Pipe = 1000 mm = 1 m
2)Then both the ends of the pipe are closed with lids using create lids option present in ribbon.
3)Next, line probes are placed at 95%, 90% and 85% of the pipe length by inlet, i.e. at 950 mm, 900 mm and 850 mm from inlet respectively.
4)Next, create a new project and go to general settings, there ,in the initial conditions select the water as a Fluid of and flow of Laminar and Turbulent type.
5)Now the boundary conditions inserted are
- Static Pressure of 101325 Pa & temperature 293.2 K at outlet.
- Inlet velocity calculated corresponding to the reynolds no value 100 at the inlet lid.
- Inner wall of pipe as real wall.
6)Next, a Basic Mesh is created and the definitions of the Global Mesh is edited by selecting Manual type and setting 10 for Nx, 10 for Ny and 50 for Nz.
7)Further, XY Plots and Cut Plots for velocity is created at the 3 different Line Probes drawn earlier.
8)Finally create a New Parametric Study, add Simulation Parameters in Input Variables, Inlet Velocity (Normal to Face Parameter) Boundary Condition and select all the XY and cut plots for output parameter. Further, create 2 new design points with the Inlet Velocities of reynolds no 1000 and 1000.
9)RUN the Simulation.
6.RESULTS :
1)CUT PLOTS FOR VARIOUS REYNOLDS NO VALUES
i) Re=100
Velocity profile at 85% of length
Velocity profile at 90% of length
Velocity profile at 95% of length
Explanation:-
The 3 cut plot shows the velocity contour at 850, 900 and 950 mm length from the inlet of pipe, the varying velocity across radial direction shows the parabolic nature of the fully developed flow. Not much difference can be noticed in the contours at these locations as the flow is laminar and has become full developed after flowing a significant amount of distance, thus the flow continues to be in same motion.
Cut section showing Flow
The cut plot shows the flow of fluid inside pipe, the laminar and parabolic nature of the flow can be seen from the contour.
ii) Re=1000
Velocity profile at 85% of length
Velocity profile at 90% of length
Velocity profile at 95% of length
Explanation:-
The 3 cut plot shows the velocity contour at 850, 900 and 950 mm length from the inlet of pipe, the varying velocity across radial direction shows the parabolic nature of the fully developed flow. Not much difference can be noticed in the contours at these locations as the flow is laminar and has become full developed after flowing a significant amount of distance, thus the flow continues to be in same motion.
The center portion of the flow showing maximum velocity has increased because of increase in magnitude of velociy which results in less flow resistance at boundary.
Cut section showing Flow
The cut plot shows the flow of fluid inside pipe, the laminar and parabolic nature of the flow can be seen from the contour.
iii) Re=10000
Velocity profile at 85% of length
Velocity profile at 90% of length
Velocity profile at 95% of length
Explanation:-
The 3 cut plot shows the velocity contour at 850, 900 and 950 mm length from the inlet of pipe, the varying velocity across radial direction shows the parabolic nature of the flow. Not much difference can be noticed in the contours at these locations as the flow has become full developed after flowing a significant amount of distance, thus the flow continues to be in same motion.
The turbulent nature of the flow is evident from the contour at edges of pipe where the motion is unsteady.
Due to increase in magnitude of velocity the center portion of the flow showing maximum velocity has increased which results in less resistance and high tubulence at boundary.
Cut section showing Flow
The cut plot shows the flow of fluid inside pipe, the turbulent and parabolic nature of the flow can be seen from the contour.
2)VELOCITY PROFILE COMPRASION OF VARIOUS REYNOLDS NO VALUES
i) At 85% of length
ii) At 90% of length
iii) At 95% of length
Explanation
The 3 plot shows the comparison of velocity cross section at 850, 900 and 950 mm length from the inlet respectively for reynolds number 100 (Design Point 1 sketch 4), 1000 (Design Point 2 sketch 4) and 10000 (Design Point 3 sketch 4).
It can be seen that as the reynolds number increase the magnitude of velocity increase, the maximum amount of increase can be noticed at the center portion of the cross section. For reynolds number of 10000 there is a sudden increase in velocity at center and at boundaries due to turbulence.
Not much difference can be noticed in these 3 plots as the flow has become full developed after flowing a significant amount of distance, thus the flow continues to be in same motion.
7.CONCLUSION :
As we increase the reynolds number the velocity increases, resistance at boundary decreases and after a certain amount of increase the turbulence increases which can be seen from Re no 10000 case results.
8.REFERENCES :