This project presents a computational fluid dynamics (CFD) analysis of laminar flow development inside a circular pipe using ANSYS Fluent and ANSYS CFX.
The objective of this study is to investigate the hydrodynamic development length in internal pipe flow and analyze how Reynolds number affects the velocity distribution and entrance region behavior.
The project includes:
- Theoretical analysis of Hagen–Poiseuille flow
- CFD simulation of laminar incompressible flow
- Parametric study for multiple Reynolds numbers
- Velocity profile analysis
- Development length estimation
- Comparison between Fluent and CFX results
- Validation using analytical relations
Laminar incompressible flow inside a circular pipe is commonly known as Hagen–Poiseuille flow.
As fluid enters a pipe with a uniform inlet velocity profile, boundary layers develop near the walls due to viscous effects. These layers gradually grow and merge until the velocity profile becomes fully developed and parabolic.
The entrance length for laminar pipe flow can be estimated using:
L = 0.065 × Re × D
Where:
L= hydrodynamic development lengthRe= Reynolds numberD= pipe diameter
The main goals of this project are:
- Simulate laminar flow inside a circular pipe
- Investigate the effect of Reynolds number on development length
- Observe the formation of the fully developed parabolic velocity profile
- Compare analytical and numerical results
- Compare Fluent and CFX simulations
- ANSYS Fluent
- ANSYS CFX
- ANSYS Meshing
- ANSYS DesignModeler
A circular pipe with:
- Length = 3 m
- Radius = 0.1 m
was modeled for the simulations.
A structured mesh was generated for the pipe domain to ensure stable and accurate numerical results.
The following conditions were applied:
- Inlet velocity = 1 m/s
- Outlet gauge pressure = 0 Pa
- No-slip condition at pipe walls
- Steady laminar incompressible flow
Different Reynolds numbers were obtained by changing the dynamic viscosity.
| Reynolds Number | Dynamic Viscosity (kg/m·s) |
|---|---|
| 100 | 0.002 |
| 150 | 0.00133 |
| 200 | 0.001 |
The analytical development lengths were calculated using:
L = 0.065 × Re × D
| Reynolds Number | Development Length (m) |
|---|---|
| 100 | 1.3 |
| 150 | 1.95 |
| 200 | 2.6 |
The velocity profile develops gradually from a uniform inlet profile to a fully developed parabolic profile.
The fully developed velocity distribution inside the pipe follows the expected parabolic behavior predicted by Hagen–Poiseuille theory.
The problem was also solved using ANSYS CFX for Reynolds number 100.
The comparison between Fluent and CFX showed good agreement in predicting axial velocity development.
- Development length increases with increasing Reynolds number.
- The fully developed region occurs farther downstream for larger Reynolds numbers.
- Velocity becomes parabolic in the fully developed region.
- Maximum velocity occurs at the pipe centerline.
- Maximum velocity is approximately twice the average velocity.
- Fluent and CFX produced closely matching results.
- CFX showed slightly faster convergence behavior.
This project is based on:
- Navier–Stokes equations
- Continuity equation
- Hagen–Poiseuille flow theory
- Laminar internal flow analysis
- Hydrodynamic entrance length
pipe-flow-development-length-ansys/
│
├── README.md
│
├── report/
│ └── pipe-flow-development-length-report.pdf
│
├── images/
│ ├── geometry/
│ ├── mesh/
│ ├── results/
│ └── cfx-comparison/
│
├── data/
│
└── fluent-setup/
└── simulation-notes.md
- Frank M. White — Fluid Mechanics
- ANSYS Fluent Documentation
- ANSYS CFX Documentation
Ali Darfashi Mechanical Engineering Student Computational Fluid Dynamics (CFD) Enthusiast