Velocity Distribution at the Cross-Over of Sinusoidal Trapezoidal Meandering Channels

Evaluation of velocity distribution process longitudinally is very much essential for the environmental management, quantifying the mean velocity. In nature, most rivers tend to be of compound sections as well as meandering [1]. Velocity distribution is crucial for solving many engineering problems such as management of rivers and floodplains, it is important to understand the behaviours of flows within compound channels for designing of hydraulic structure, flood control, water management, sedimentation and excavation. During flood runoff water comes out natural or man-made channel, part of the discharge is carried out by simple main channel rest are carried out by flood plain. Experiment results are presented here for the studies conducted in two self designed channels, developed by known discharge. These data’s were used for the analysis of velocity distribution and depth average. Velocity at the cross-over of a meandering channel of different sinuosity at various flow depth where investigated for monitoring the contour mapping of flow and graphical analysis of velocity at the cross-over

Baffle Type Energy Dissipator for Pipe Outlets

The baffle type energy dissipator described in this paper was developed through laboratory experimentation for use in soil conservation work. It is designed to reduce the energy in high velocity pipe flow so that the water may be discharged safely into an erodible channel. This structure can be adapted to meet the many field conditions encountered in erosion control work in agriculture and elsewhere, such as at pipe outlets draining terraces or ditches, highway culverts, and drop inlet spillway outlets. Pipe sizes commonly used in such applications range from 10 to 48 in in diameter and have flows from 10 to 250 cfs discharging into channels of various widths

Microfluidic systems for in situ formation of nylon 6,6 membranes.

A microfluidics based, localised formation of nylon 6,6 membranes has been undertaken. The study demonstrates the feasibility of maintaining stable aqueous/organic interfaces for xylene within simple linear flow channels. Glass fabricated structures were used with adipoyl chloride and hexamethylenediamine in the organic and aqueous phases, respectively, in order to achieve nylon 6,6 interfacial polymerisation. Localised membrane formation was investigated in flow channels of different geometries over a wide range of flow rates (500–4000 μl/min), with Reynolds numbers ranging from 8.4 to 67.2. The results demonstrate that interfacial polymerisation occurs consistently over a wide range of flow rates and of flow entry angles for dual aqueous/organic solvent input. However, creation of uniform planar film structures required careful optimisation, and these were best achieved at 2000 μl/min with a flow entry angle of 45°. The resulting membranes had thicknesses in the range between 100 and 300 μm. Computational modelling of the aqueous/organic flow was performed in order to characterise flow stability and wall shear-stress patterns. The flow arrangement establishes a principle for the fabrication of micromembrane structures designed for low sample volume separation, where the forming reaction is a facile and rapid interfacial process

A numerical method for junctions in networks of shallow-water channels

There is growing interest in developing mathematical models and appropriate numerical methods for problems involving networks formed by, essentially, one-dimensional (1D) domains joined by junctions. Examples include hyperbolic equations in networks of gas tubes, water channels and vessel networks for blood and lymph in the human circulatory system. A key point in designing numerical methods for such applications is the treatment of junctions, i.e. points at which two or more 1D domains converge and where the flow exhibits multidimensional behaviour. This paper focuses on the design of methods for networks of water channels. Our methods adopt the finite volume approach to make full use of the two-dimensional shallow water equations on the true physical domain, locally at junctions, while solving the usual one-dimensional shallow water equations away from the junctions. In addition to mass conservation, our methods enforce conservation of momentum at junctions; the latter seems to be the missing element in methods currently available. Apart from simplicity and robustness, the salient feature of the proposed methods is their ability to successfully deal with transcritical and supercritical flows at junctions, a property not enjoyed by existing published methodologies. Systematic assessment of the proposed methods for a variety of flow configurations is carried out. The methods are directly applicable to other systems, provided the multidimensional versions of the 1D equations are available

Hydrodynamic Impacts of a Marine Renewable Energy Installation on the Benthic Boundary Layer in a Tidal Channel

Peer reviewedPublisher PD

Risk Based Urban Watershed Management Under Conflicting Objectives

Ecological impairment and flooding caused by urbanization can be expressed numerically by calculating the risks throughout the watershed (floodplain) and along the main stems of the streams. The risks can be evaluated in terms of the present and/or future. This article describes the methodologies for ascertaining the risks in the Geographical Information Systems (GIS) environment. The objectives of urban flood controls and ecological preservation/restoration of urban waters are often conflicting and, in the past, the sole emphasis on flood control led to destruction of habitat and deterioration of water quality. An optimal solution to these two problems may be achieved by linking the risks to the concepts of risk communication, risk perception, and public willingness to pay for projects leading to ecological restoration and ecologically sustainable flood control. This method is appropriate because, in each case, public funds are used and the projects require approval and backing of policy makers and stakeholders. This article briefly describes a research project that attempts to resolve the conflict between the flood protection and stream ecological preservation and restoration and suggests alternative ways of expressing benefits of urban stream flood control and restoration projects

Liquid - liquid flows in microchannels

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.In this work the flow patterns are investigated during the flow of an ionic liquid and deionized water mixture in a glass microchannel (0.2mm I.D) for two different inlet configurations (T- and Yjunction). The density, viscosity and surface tension of the ionic liquid [C4mim][NTf2] are 1420kg/m3 , 0.029Pa·s and 31.92mN/m respectively. The water phase has a density of 1000kg/m3, a viscosity of 0.001Pa·s and a surface tension of 73,69mN/m. In most of the patterns observed water was the continuous phase with the ionic liquid forming plugs or a mixture of plugs and drops within it. With the Y-junction and at high mixture velocities a separated pattern was observed with the two fluids flowing in parallel along the channel for the middle range of ionic liquid fractions, while water dispersed as drops was found at high ionic liquid fractions. Pressure drop was measured during regular plug flow which revealed that for the same ionic liquid superficial velocity the pressure drop was lower when it flowed in a mixture with water than when it was on its own in the channel. For a xonstant ionic liquid flow rate, pressure drop decreased as the ionic liquid fraction increased.The project is funded by the Engineering and Physical Sciences Research Council (EPSRC) and the Energy Institute at UCL

On emerging micro- and nanoscale thermofluidic technologies

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.This paper highlights examples of my current research in heat transfer and fluidics at the interface of energy applications and micro- and nanoscale technologies. It is not the scope of this paper to present an exhaustive account of all current and past activities related to its title. It is rather an account of current research in my laboratory in this area, containing both the underlying scientific challenges as well as the hoped final outcome in terms of applications. To this end, examples from the areas of energy conversion, as well as energy transport will be discussed. In the area of energy conversion an original, deformable, direct methanol microfuel cell will be presented made of lightweight, flexible, polymer-based materials. A basic understanding and control of two-phase flows (in this case methanol and carbon dioxide) in microchannels as well as novel materials processing and microfabrication methods are directly related to the performance of such energy conversion devices. In the area of energy conservation and reuse, examples from the information technology are employed. Specifically, new concepts of liquid (water) cooling of chips reaching heat removal rates in excess of 700 W/cm2 in domains with restricted heights of the order of one mm will be presented. One additional advantage of using water to cool high density electronics is energy reuse, due to the potentially much higher exergy content of the coolant compared to air cooled technologies. The last part of the paper focuses on the employment of functional nanostructures such as carbon nanotubes and nanowires of conductive and semiconductive materials for the efficient transport of electricity and heat and the need for the development of novel technologies for the manufacturing, characterization as well as handling of such nanostructures