On the variety of particle accumulation structures under the effect of g-jitters

Lappa, Marcello

doi:10.1017/jfm.2013.203

Cited by 40 publications

(59 citation statements)

References 82 publications

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“…The typical (non-dimensional) time integration step used for all the simulation has been set to 10 -8 (satisfying two different criteria, namely the well-known conditions for the numerical stability of the diffusive and convective equation terms appearing in both the momentum and energy equation, see, e.g., Ref 78 The CFD kernel of the present code was successfully used for numerous studies of fundamental fluid-dynamics (the reader being referred to Lappa 20 for an assessment of the code performances for a typical problem of turbulent gravitational convection) and repeatedly validated also by comparison with other kinds of convection (of various natures, see, e.g., Refs. 47,78 ).…”

Section: Solution Methods and Mesh Refinement Studymentioning

confidence: 99%

“…For the sake of consistency with earlier works addressing companion subjects [47][48][49][50][51][52][53] , as the characteristic time scale of the fluid flow, we consider:…”

Section: Solid Mattermentioning

confidence: 99%

“…These mechanism are made particularly complex by the fact that, in addition to being compressible, just as thermal convection (see, e.g., Lappa 46 ), particle dynamics are, in general, dissipative. Continuing our computational investigation (see, e.g., Refs [47][48][49][50][51][52][53] ) into this general area, in the present study (unlike earlier works, which considered synthetic flows, isotropic turbulence or other circumstances) we target expressly the case of particles interacting with thermal plumes in thermogravitational flow. An increased understanding of these processes (see, e.g., Gan et al, 54 ;…”

Section: Introductionmentioning

confidence: 99%

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On the transport, segregation, and dispersion of heavy and light particles interacting with rising thermal plumes

Lappa

2018

Physics of Fluids

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A systematic numerical analysis is carried out on the multiplicity of patterns produced by inertial particles dispersed in a fluid and localized gravitational convection developing in the form of a rising thermal plume. In particular, specific numerical examples are presented to provide inputs for an increased understanding of the underlying flow-particle interaction mechanisms and cause-and-effect relationships. A rich spectrum of convective dynamics is obtained at the relatively high value of the considered Rayleigh number (Ra=10 8 ), which naturally allows the investigation of several intriguing effects (including, but not limited to, particle interaction with plume jet, associated vortices, shear instabilities and symmetry breaking phenomena). An important degree of freedom is introduced in the problem by changing the particle viscous drag through proper tuning of the related Stokes number (St). Similarly, inertia and weight of solid matter are varied parametrically by performing numerical simulations for both light and heavy particles at different values of the Froude number. This framework lets us identify the average behaviour of particles by revealing the mean evolution. We connect such statistics to the behaviour of the temporally evolving thermal plume, giving deeper insights into the particle transport mechanisms and associated dissipative dynamics.

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Section: Solution Methods and Mesh Refinement Studymentioning

confidence: 99%

“…For the sake of consistency with earlier works addressing companion subjects [47][48][49][50][51][52][53] , as the characteristic time scale of the fluid flow, we consider:…”

Section: Solid Mattermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the transport, segregation, and dispersion of heavy and light particles interacting with rising thermal plumes

Lappa

2018

Physics of Fluids

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“…where L is the characteristic size of the considered geometrical domain 28 , and  the fluid kinematic viscosity). The resulting non-dimensional ratio reads…”

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confidence: 99%

On the propagation and multiple reflections of a blast wave travelling through a dusty gas in a closed box

2017

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This version is available at https://strathprints.strath.ac.uk/60148/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. Accepted for Publication in the Physics of Fluids -10 March 20171 On the propagation and multiple reflections of a blast wave travelling through a dusty gas in a closed box Abstract: This paper concerns the propagation of shock waves in an enclosure filled with dusty gas. The main motivation for this problem is to probe the effect on such dynamics of solid particles dispersed in the fluid medium. This subject, which has attracted so much attention over recent years given its important implications in the study of the structural stability of systems exposed to highenergy internal detonations, is approached here in the framework of a hybrid numerical two-way coupled Eulerian-Lagrangian methodology. In particular, insights are sought by considering a relatively simple archetypal setting corresponding to a shock wave originating from a small spherical region initialized on the basis of available analytic solutions. The response of the system is explored numerically with respect to several parameters, including the blast intensity (via the related value of the initial shock Mach number), the solid mass fraction (mass load), and the particle size (Stokes number). Results are presented in terms of pressure-load diagrams. Beyond practical applications, it is shown that a kaleidoscope of fascinating patterns is produced by the "triadic" relationships among multiple shock reflections events and particle-fluid and particle-wall interaction dynamics. These would be of great interest to researchers and scientists interested in fundamental problems relating to the general theory of pattern formation in complex nonlinear multiphase systems.

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“…For the first case the method was verified on the test case reported by Melnikov et al, 43 (results of the validation study are summarized in Table I, the reader being also referred to Ref. 44 for further details). Results for the full-zone (silicone oil with properties shown in Table II) are summarized in Fig.…”

Section: Grid Refinement and Validationmentioning

confidence: 99%

On the onset of multi-wave patterns in laterally heated floating zones for slightly supercritical conditions

Lappa

2016

Physics of Fluids

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This analysis follows and integrates the line of inquiry started in past author's works (Phys. Fluids, 15(3): 776-789, 2003, and Phys. Fluids 16(2): 331-343, 2004) about the typical instabilities of Marangoni flow and associated hierarchy of bifurcations in laterally heated floating zones with various shapes and aspect ratios. The main motivation for re-examining this kind of problems, which so much attention have attracted over the last twenty years, is the recent discovery (Kudo, Ueno and Kawamura, (2014), in Japanese, DOI: 10.1299/transjsme.2014tep0095) of a chaotic state in region of the space of parameters where on the basis of existing theories and earlier results for the classical liquid-bridge problem with organic fluids, the flow should be relatively regular in time and with a simple structure in space. Axisymmetric computations are used to obtain the steady basic state, and then the Navier Stokes equations are solved in their complete, threedimensional, time-dependent and non-linear formulation to investigate the evolution of azimuthal disturbances. It is shown that the "apparent" doubling or quadrupling of the azimuthal wavenumber in the equatorial plane, previously reported for the case of floating zones of liquid metals, is replaced for high-Prandtl-number liquids by the complex interaction of disturbances with distinct spatial and temporal scales. These disturbances become critical at relatively comparable values of the Marangoni number. The unexpected multiplicity of waveforms and competition of spatial modes is explained according to the increased complexity of the considered system in terms of flow topology and structure with respect to the classical half-zone configuration.

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On the variety of particle accumulation structures under the effect of g-jitters

Cited by 40 publications

References 82 publications

On the transport, segregation, and dispersion of heavy and light particles interacting with rising thermal plumes

On the transport, segregation, and dispersion of heavy and light particles interacting with rising thermal plumes

On the propagation and multiple reflections of a blast wave travelling through a dusty gas in a closed box

On the onset of multi-wave patterns in laterally heated floating zones for slightly supercritical conditions

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