Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 25 for “"Granular Flows"”.
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Modelling dry granular flows over topography
Dry granular flows are common and important in the environment and industry, and yet their behaviour is very poorly understood. The dynamics of individual grains are governed by the simple and well-known laws of Newtonian mechanics, but how do these 'microscopic' particle-level laws translate into …
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Multi-scale multiphase modelling of granular flows
… hazards usually involve multiphase flow of dense granular solids and water. Understanding the mechanics of granular flow is of particular importance in predicting the run-out behaviour of debris flows. The dynamics of a homogeneous granular flow involve three distinct scales: the microscopic …
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Axial segregation of granular flows in rotating drums
… in rotating drums is presented for mixtures of granular material. We show that grains composed of different material properties which are heuristically argued to manifest as differences in frictional properties at the continuum scale-diffuse into axial bands as a consequence of concentration …
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Several applications of a model for dense granular flows
… continuum model for the dense flow of dry granular materials (Jop, Forterre & Pouliquen, 2006, Nature, 441, 167-192). The model, based upon a generalisation of Coulomb sliding friction, is known to perform well when modelling certain simple free surface flows. We extend the application of …
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Discrete Element Modeling of Granular Flows in Vibrationally-fluidized Beds
… project was to develop a model for the motion of granular media under vibration in a tub vibrator. For such a system, it was decided that a discrete element method (DEM) was the most appropriate tool to model bulk velocity and circulation of media. In the first phase of the work, a vibratory …
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Discrete element simulations and constitutive modeling of dense granular flows
… and explore the rheology of</p> <p>dense granular flow, in particular the phenomenon of regime</p> <p>transition, using both microscale DEM (discrete element method)</p> <p>simulations and macroscale modeling methods. The rheology of dense sheared granular flow in a Couette device is …
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Mechanics and numerical simulations of Dry Granular Flows driven by gravity
The gravitational granular flows (e.g. debris flows or snow avalanches) are catastrophic and destructive phenomena affecting many areas in the world, and especially the mountain areas of Europe. Proper design criteria are required in order to improve protection structures and prevention strategies. …
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Investigation of infinite-dimensional dynamical system models applicable to granular flows
… The BSR models were originally derived to model granular flows, but they actually have many additional applications in a variety of fields. BSR models have already been proven to be completely integrable infinite-dimensional Hamiltonian dynamical systems for perfectly elastic interactions in the …
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A 4D photogrammetric system for studying flow-like landslides
… landslide models. The hardware captures granular flows as time-series three-dimensional (4D) point clouds, producing high-quality digital datasets of laboratory landslide experiments. The software incorporates a robust tracking algorithm, enabling the calculation of flow velocity vectors …
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A granular flow model of an annular shear cell
… minerals to be extracted are best modelled using granular flows. A single rheological description that captures all the features of granular flows has not yet been realised, although considerable progress towards a complete theory has been made. Existing models of such horizontally stirred mills …
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Simulation of free-surface flows and development of an improved particle method
… useful numerical tools for studying free-surface flows in various engineering problems. They are able to easily simulate complicated fluid interface flows. As a Lagrangian method, MPS with a weakly-compressible technique, Weakly-Compressible Moving Particle Semi-implicit method (WC-MPS), has been …
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Experimental Investigation of Liquid and Particle -Laden Flows in Microtubes
… similar to the arching phenomenon common to granular flows. Orthokinetic flocculation occurs when shear-induced particle collisions result in particles attaching by surface forces to form large groups of physically connected particles (flocs). It is also suggested as a mechanism for blockage …
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Segregation of granular particles in suspension flow
… the development of longitudinal stripes of granular particles due to instabilities in particle suspension flow. Research was conducted to characterize environmental phenomena related to granular flows, namely avalanches, mudslides, and the movement of glaciers. Results show the stripes were …
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Spreading of viscous fluids and granular materials on slopes
… and industrial contexts, including lava flows on volcanoes and thin films on coated surfaces. The aim of my research is to provide quantitative insight into these forms of motion and their dependence on effects of the topography, the volume and the rheology of the flowing structure. …
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Quantifying Geomorphic Features: Relative Albedos, Skeletonization, and Multifractality
… at the study site are more likely formed by dry granular flows than by groundwater. In a second investigation, I describe a new algorithm to derive the skeleton of a geomorphic polygon, such as the centerline for a river. This geomorphic study provides a persuasive illustration that geomorphology …
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Instabilities in particle-laden flows
… in many industrial processes and in nature. Dry granular flows and suspensions have been well studied and present a broad range of problems in terms of rheology and instabilities. In both cases, new phenomena are continually discovered. Indeed, complex behavior can be exhibited whether the …
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Non-isothermal dynamics of thin-film free-surface and channel flows of non-Newtonian nanofluids
… fluids (e.g. worm-like micellar solutions, granular flows, polymer solutions and some polymer melts) reveal flow instabilities within the flow field, such as the emergence of regions of different shear bands due to the flow induced material non-homogeneities. It has also been observed that …
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Reduced model for particle laden flow
… It is well known that when a clear viscous fluid flows down an inclined surface under gravity, after some time, the initially straight contact line becomes unstable with respect to transverse perturbations. Clear fluid is easier to use in experiments, but industrial processes usually involve …
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Photoelastic study of dense granular free-surface flow rheology and size segregation
… challenges facing experimental studies of granular rheology is the opacity of the constitutive particles, which prevents direct observations of their behaviour and interactions. This thesis describes a series of original experiments where instantaneous forces between individual particles …
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