W.J. Hogendoorn
13 records found
1
Magnetic resonance imaging in granular flows
An overview of recent advances
In this review we explore the recent developments in the use of Magnetic Resonance Imaging (MRI) for studying granular flows. While MRI has been a valuable tool in this field for the past 40 years, recent advances in imaging hardware, reconstruction software and particles synthes
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Ultrasound imaging velocimetry (UIV) is a maturing technique for measuring the dispersed phase in two-phase flows. It enables measurements of dense suspensions when optical methods fail. This study explores UIV’s applicability to measure the flow field in a swirling flow reactor
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From nearly homogeneous to core-peaking suspensions
Insight in suspension pipe flows using MRI and DNS
Magnetic resonance imaging (MRI) experiments have been performed in conjunction with direct numerical simulations (DNS) to study neutrally buoyant particle-laden pipe flows. The flows are characterized by the suspension liquid Reynolds number (Res), based on the bulk liquid veloc
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Ultrasound imaging velocimetry in particle-laden flows
Counteracting attenuation with correlation averaging
Abstract: Ultrasound imaging velocimetry (UIV) refers to the technique wherein ultrasound images are analysed with 2D cross-correlation techniques developed originally in the framework of particle image velocimetry. Applying UIV to opaque, particle-laden multiphase flows have lon
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Using magnetic resonance imaging we are able to obtain average velocity and volume fraction profiles in a pipe flow with a neutrally buoyant suspension. In this experimental work, the effect of increasing Reynolds number and particle volume fraction on shear-induced migration is
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We propose a scaling law for the onset of turbulence in pipe flow of neutrally buoyant suspensions. This scaling law, based on a large set of experimental data, relates the amplitude of the particle-induced perturbations ε to the critical suspension Reynolds number Res,c. Here ε
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Suspension flows are abundantly present in nature and industry. Typical examples include volcanic ash clouds, sediment transport in rivers, blood flow through human capillaries and the dredging industries. Accurate models of suspension flows are of key importance for prediction,
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Ultrasonic particle volume fraction profiling
An evaluation of empirical approaches
Abstract: We discuss empirical techniques to extract quantitative particle volume fraction profiles in particle-laden flows using an ultrasound transducer. A key step involves probing several uniform suspensions with varying bulk volume fractions from which two key volume fractio
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Particle-laden pipe flows exhibit a gradual laminar-turbulent transition, beyond a critical volume fraction (φ). While classical transition behavior is characterized by the presence of turbulent puffs, this intermittent nature is absent for particle-induced transition. For small
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Magnetic resonance velocimetry in high‑speed turbulent flows
Sources of measurement errors and a new approach for higher accuracy
This study focuses on the measurement accuracy of Magnetic Resonance Velocimetry (MRV) in high-speed turbulent flows. One of the most prominent errors in MRV is the displacement error, which describes the misregistration of spatial coordinates and velocity components in moving fl
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Using ultrasound in plane wave imaging mode, in combination with a proper processing strategy and the covariance function approach, we can not only better estimate the actual turbulence statistics, but we are also able to measure turbulent flows with much higher Reynolds numbers.
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Partial cavitation dynamics in an axisymmetric converging-diverging nozzle are investigated experimentally. Shadowgraphy is used to visualize and analyze different cavitation regimes. These regimes are generated by changing the global static pressure and flow velocity independent
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Using ultrasound imaging velocimetry, we are able to present unique insight in transitional particle-laden flows. Together with a Moody diagram of time-averaged properties, we demonstrate that the laminar-turbulent transition behavior at high volume fractions is distinct from the
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