# Velocity Profiles and Unsteady Pipe Friction in Transient Flow

@article{Brunone2000VelocityPA, title={Velocity Profiles and Unsteady Pipe Friction in Transient Flow}, author={Bruno Brunone and Bryan W Karney and Michele Mecarelli and Marco Ferrante}, journal={Journal of Water Resources Planning and Management}, year={2000}, volume={126}, pages={236-244} }

Transient conditions in closed conduits have traditionally been modeled as 1D flows with the implicit assumption that velocity profile and friction losses can be accurately predicted using equivalent 1D velocities. Although more complex fluid models have been suggested, there has been little direct experimental basis for selecting one model over another. This paper briefly reviews the significance of the 1D assumption and the historical approaches proposed for improving the numerical modeling…

## 194 Citations

### Numerical Simulation of Unsteady Friction in Transient Two-Phase Flow with Godunov Method

- Physics
- 2013

Most numerical transient flow models that consider dynamic friction
employ a finite differences approach or the method of characteristics. These
models assume a single fluid (water only) with…

### Experimental Study of the Transient Flow in a Coiled Pipe Using PIV

- Engineering, Physics
- 2017

AbstractA comprehensive knowledge of energy dissipation during the accelerations and decelerations in transient flow is essential to develop robust and accurate hydraulic transient solvers.…

### Unsteady Friction in Rough Pipes

- Engineering, Physics
- 2001

An energy dissipation model is presented for the computation of unsteady friction losses adapted to smooth-to-rough transition and fully rough pipes. The eddy viscosity model used to compute the…

### Effect of Unsteady Friction Models and Friction-Loss Integration on Transient Pipe Flow

- Engineering
- 2006

When velocities in the piping systems change rapidly, spectacular accidents occur, due to transient-state pressures where the elastic properties of the pipe and liquid must be considered. This…

### Evaluation of Transient Hydraulic Flow in Flexible Pipe Line

- Engineering
- 2012

Water-hammer is a transient condition which may occur in a network as a result of rapid or slow valve closures, pump failures, etc. It creates high and low pressure waves which travel along the…

### Unsteady friction in transient vertical-pipe flow with trapped air

- Engineering, PhysicsJournal of Hydraulic Research
- 2020

ABSTRACT Existing pipe-filling models have primarily considered steady friction alone, tending to underestimate pressure attenuation. Various popular unsteady friction models are considered here to…

### Unsteady Velocity Profiles in Laminar and Turbulent Water Hammer Flows

- Engineering, Physics
- 2009

The behavior of unsteady velocity profiles in laminar and turbulent water hammer flows is numerically investigated. In this way, the governing equations for the quasitwo-dimensional equations of…

### Numerical simulation of laminar water hammer flow in a pipe with varying cross-section

- Engineering
- 2018

Numerical simulation of water hammer effect in a pipe with varying cross-section is presented for an initial laminar flow by solving Navier–Stokes equations in time, using Ansys Fluent software.…

### UNSTEADY FRICTION IN A RAPID FILLING PIPELINE WITH TRAPPED AIR

- Physics, Engineering38th IAHR World Congress - "Water: Connecting the World"
- 2019

This work investigates the effects of unsteady friction in a rapid filling pipeline with an entrapped air pocket. Existing one-dimensional transient pipe-filling models have primarily considered only…

## References

SHOWING 1-10 OF 32 REFERENCES

### A Boundary-Layer Theory for Transient Viscous Losses in Turbulent Flow

- Engineering, Physics
- 1970

A laminar boundary-layer model is proposed to account for viscous losses during the transient turbulent flow of a liquid in a tube. In this model, inviscid slug flow is assumed for the core and all…

### Transient, turbulent, smooth pipe friction

- Engineering, Physics
- 1995

Two of the most promising analytical models of unsteady friction in turbulent pipe flows are based on sharply contrasting hypotheses. One uses the history of the flow; the other uses instantaneous…

### COMPUTATION OF ENERGY DISSIPATION IN TRANSIENT FLOW

- Physics, Engineering
- 1997

A new model for the computation of unsteady friction losses in transient flow is developed and verified in this study. The energy dissipation in transient flow is estimated from the instantaneous…

### Effects of Two-Dimensionality on Pipe Transients Modeling

- Engineering
- 1995

The paper discusses the rapid damping of pressure peaks in a water-hammer phenomenon after the end of a complete valve-closure maneuver. This effect is due to flow characteristics not considered when…

### A weighting function model of transient turbulent pipe friction

- Engineering, Physics
- 1993

A weighting function model of transient turbulent pipe friction at moderate Reynolds Numbers is developed in a similar manner to Zielke's equivalent expression for laminar flow (1968). It is shown…

### FRICTION--FREQUENCY DEPENDENCE FOR OSCILLATORY FLOWS IN CIRCULAR PIPE

- Engineering
- 1973

Measured data of velocity changes in oscillatory flows (0.16Hz-0.36Hz) are presented. The actual wall shear stresses obtained from the measurements are compared to calculated values based on steady…

### Efficient inverse transient analysis in series pipe systems

- Engineering
- 1999

Measurement of the changes in heads initiated by a valve closure are used to calibrate the friction factors in a hydraulic system consisting of a series-connected pipeline and a downstream valve…

### An Efficient Method for Simulating Frequency-Dependent Friction in Transient Liquid Flow

- Engineering
- 1975

.1. T. KARAM, JR. The author is to be highly commended for developing a practical scheme for including frequency-dependentfriction effects in a method-of-characteristics solution scheme for line…

### The damping of flow and pressure oscillations in water hammer analysis

- Engineering
- 1989

The Darcy-Weisbach formula, used in the majority of mathematic models for calculating the head losses in the unsteady motion of water does not simulate with sufficient accuracy the damping of flow…

### Resistance Coefficients for Accelerated and Decelerated Flows Through Smooth Tubes and Orifices

- EngineeringJournal of Fluids Engineering
- 1956

This paper is a summary of the results of investigations of the drop in potential and boundary resistance in unsteady motion for cases of surface resistance caused by boundary shear stresses and…