Waves and Turbulence in Core-Annular Pipe Flow

When a very viscous liquid (like oil) and a far less viscous liquid (like water) both flow through a pipeline, under certain conditions, the more viscous liquid will migrate to the core of the pipe, while being surrounded by an annulus with the less viscous liquid. This typical flow pattern, referred to as core-annular flow (CAF), was discovered...

Assessment of numerical methods for estimating the wall shear stress in turbulent Herschel–Bulkley slurries in circular pipes

This article concerns the turbulent flow of Herschel–Bulkley slurries through circular horizontal pipes; in particular, that of concentrated domestic slurry obtained upon separation of domestic waste water and reduction in the use of water for domestic purposes. Experiments with a rheologically equivalent clay (kaolin) slurry indicated a non...

On the levitation force in horizontal core-annular flow with a large viscosity ratio and small density ratio

A numerical study has been made of horizontal core-annular flow: the flow of a high-viscosity liquid core surrounded by a low-viscosity liquid annular layer through a horizontal pipe. Special attention is paid to the question how the buoyancy force on the core, caused by a density difference between the core and the annular layer, is...

Self-similar drag reduction in plug-flow of suspensions of macroscopic fibers

Pipe flow experiments show that turbulent drag reduction in plug-flow of concentrated suspensions of macroscopic fibers is a self-similar function of the wall shear stress over the fiber network yield stress. We model the experimental observations, by assuming a central fiber network plug, whose radius is determined by the yield stress....

An experimental study of transitional pulsatile pipe flow

The transitional regime of a sinusoidal pulsatile flow in a straight, rigid pipe is investigated using particle image velocimetry. The main aim is to investigate how the critical Reynolds number is affected by different pulsatile conditions, expressed as the Womersley number and the oscillatory Reynolds number. The transition occurs in the...

Localized turbulence in pipe flow

In this thesis the transition to turbulence in pipe flow is investigated. At low Reynolds numbers, the flow returns to the laminar state spontaneously. At high Reynolds number a small perturbation causes the flow to suddenly become turbulent. In the intermediate regime localized turbulence is observed. This regime is investigated using...

Guidelines on capacity reducing gas pockets in wastewater mains

Co-current air-water flow in downward sloping pipes: Transport of capacity reducing gas pockets in wastewater mains

Air-water flow is an undesired condition in many systems for the transportation of water or wastewater. Air in storm water tunnels may get trapped and negatively affect the system. Air pockets in hydropower tunnels or sewers may cause blow-back events and inadmissible pressure spikes. Water pipes and wastewater pressure mains in particular are...

Core-annular flow through a horizontal pipe: Hydrodynamic counterbalancing of buoyancy force on core

A theoretical investigation has been made of core-annular flow: the flow of a high-viscosity liquid core surrounded by a low-viscosity liquid annular layer through a horizontal pipe. Special attention is paid to the question of how the buoyancy force on the core, caused by a density difference between the core and the annular layer, is...

The pressure gradient for heterogeneous flow of coal, sand and iron in pipelines

The existing relationships based on Durand's method to predict pressure gradients for slurry flow in pipelines appear to be inadequate when accounting for a wide range of variables such as particle size and relative density as well as concentration. Using the coal, sand and iron ore data collected from various literature sources with the aid of...

Manuscripten van H.J. Schoemaker uit de periode 1946-1971: Deel B: Stroming in buisleidingen en kanalen

B1: Grondvergelijkingen van de hydrodynamica (1957) B2: Met de tijd veranderlijke stromen (1958) B3: Waterslag¹ (1959) B4: Waterslag, samendrukbare vloeistof in slappe buis met variërende doorsnede (1958) B5: Geleidelijk veranderde beweging in kanalen volgens Boussinesq (1968) B6: Geleidelijk veranderlijke beweging met zijdelingse aan- en afvoer...

History of Water-Hammer

Water-hammer is the phenomenon of the transmission of pressure and velocity surges along a pipe or conduit when a change in either the velocity or the pressure is imposed at some section in the pipe or at its ends. This change maybe imposed by some mechanical device such as a valve or by a variation in the performance of some hydraulic machinery...

Measurement of the Reynolds Stresses in a Circular Pipe as a Means of Testing a DISA Constant-Temperature Hot-Wire Anemometer

Measurements of the turbulent stresses in fully-developed pipe flow have been made as an overall test of the DISA constant-temperature hot-wire anemometer. The measurements were made with single slanting wires and a normal wire. The shearing stress was measured at two Reynolds numbers and compared with values computed from the pressure drop down...