1,720,974 research outputs found
Flow over partially liquid filled cavity
No full textExperiments have been carried out to investigate the effect of liquid cavity filling on the behavior of the gas flow over a flat plate cavity. PIV measurements in the gas phase reveal that cavity filling can affect vortex shedding in the cavity mouth. Shear layer vortices can break-up into smaller vortices, thereby losing their periodic interaction with the aft wall and, hence, their sound producing potential. Expected is that this is one of the mechanisms causing sound mitigation in corrugated pipes with liquid addition, observed in literature
Experimental verification of a theoretical model for the influence of particle inertia and of gravity on decaying turbulence in a particle-laden flow
No full textPIV-Velocimetry measurements in liquid-liquid flow simultaneously in both phases by Refractive Index Matching
No full textMeasurement of turbulent mixing in an axis-symmetric oil-water jet of micro-droplets: macroscopic and microscopic flow processes
No full textStudy of tin droplet impact on substrate at low pressure using particle tracking Velocimetry
No full textMechanical, Maritime and Materials EngineeringProcess and Energ
Cavitation: Experimental investigation of cavitation regimes in a coverging-diverging nozzle
No full textMechanical, Maritime and Materials EngineeringProcess and Energ
Exploring the potential of blood flow network data
No full textTo gain a better understanding of the role of haemodynamic forces during the development of the cardiovascular system, a series of studies have been reported recently that describe flow fields in the vasculature of model systems. Such data sets, in particular those reporting networks at multiple stages, mark a transition in the focus from single blood vessels to large parts of vascular networks. It becomes possible to investigate the behaviour of a blood vessel in the context of its surroundings, rather than as an isolated entity. In this study, a framework is presented that facilitates the analysis of such data sets. The blood vessel data is represented as a graph, with each node connected by a vessel segment with known properties. Using this framework the pressure distribution and other parameters of interest can then be estimated. Two examples are given that make use of this scheme: (1) a method to detect and reduce measurement errors in the network and (2) a method that allows the testing of various haemorheological models. For both examples a proof-of-principle result is shown.Process and EnergyMechanical, Maritime and Materials Engineerin
Experiments in particle-laden turbulence: Simultaneous particle/fluid measurements in grid-generated turbulence using particle image velocimetry
No full textApplied Science
Ultrasound imaging velocimetry: A review
No full textWhole-field velocity measurement techniques based on ultrasound imaging (a.k.a. ‘ultrasound imaging velocimetry’ or ‘echo-PIV’) have received significant attention from the fluid mechanics community in the last decade, in particular because of their ability to obtain velocity fields in flows that elude characterisation by conventional optical methods. In this review, an overview is given of the history, typical components and challenges of these techniques. The basic principles of ultrasound image formation are summarised, as well as various techniques to estimate flow velocities; the emphasis is on correlation-based techniques. Examples are given for a wide range of applications, including in vivo cardiovascular flow measurements, the characterisation of sediment transport and the characterisation of complex non-Newtonian fluids. To conclude, future opportunities are identified. These encompass not just optimisation of the accuracy and dynamic range, but also extension to other application areas.Multi Phase System
Measurement in opaque flows: a review of measurement techniques for dispersed multiphase flows
No full textA review is presented of measurement techniques to characterise dispersed multiphase flows, which are not accessible by means of conventional optical techniques. The main issues that limit the accuracy and effectiveness of optical techniques are briefly discussed: cross-talk, a reduced signal-to-noise ratio, and (biased) data drop-out. Extensions to the standard optical techniques include the use of fluorescent tracers, refractive index matching, ballistic imaging, structured illumination, and optical coherence tomography. As the first non-optical technique, a brief discussion of electrical capacitance tomography is given. While truly non-invasive, it suffers from a low resolving power. Ultrasound-based techniques have rapidly evolved from Doppler-based profiling to recent 2D approaches using feature tracking. The latter is also suitable for time-resolved flow studies. Magnetic resonance velocimetry can provide time-averaged velocity fields in 3D for the continuous phase. Finally, X-ray imaging is demonstrated to be an important tool to quantify local gas fractions. While potentially very powerful, the impact of the techniques will depend on the development of acquisition and measurement protocols for fluid mechanics, rather than for clinical imaging. This requires systematic development, aided by careful validation experiments. As theoretical predictions for multiphase flows are sparse, it is important to formulate standardised ‘benchmark’ flows to enable this validation.Multi Phase System
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