Bulletin of the American Physical Society
70th Annual Meeting of the APS Division of Fluid Dynamics
Volume 62, Number 14
Sunday–Tuesday, November 19–21, 2017; Denver, Colorado
Session D6: Multiphase Flows: Particle Laden IMultiphase Particles
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Chair: Alberto Aliseda, University of Washington Room: 406 |
Sunday, November 19, 2017 2:15PM - 2:28PM |
D6.00001: Role of dispersed particles on the dynamics of the umbrella cloud of a buoyant plume Sridhar Balasubramanian, Harish Mirajkar, Ayan Kumar Banerjee Particle-laden buoyant plume is a common occurrence in geophysical flows. We quantitatively study the modification in the plume behavior under the influence of low particle volume fraction, $\phi_{v} $. Particles with mean diameter $d_{p} =$100$\mu $m, density, $\rho_{p} =$2500 kgm$^{\mathrm{-3}}$, and $\phi_{v} =$0-0.7{\%} were injected along with the lighter plume fluid. A particle trough, characterized by radius, R, and depth, $L_{p} $, was observed and could be attributed to the phenomenon of ``particle fall-out'' and ``particle re-entrainment''. The trough either sustains or collapses depending on the plume conditions at the source. [Preview Abstract] |
Sunday, November 19, 2017 2:28PM - 2:41PM |
D6.00002: Particle Plumes Falling Through Quiescent and Turbulent Environments Alec Petersen, Luci Baker, Filippo Coletti Heavy plumes form when dense particles are injected into an ambient fluid, and are found in countless engineering and natural processes. A predictive understanding of the settling, entrainment, and spreading processes is therefore critical when assessing the environmental impact of, for example, discharging industrial waste or dredging operations. Present models focus either on very dilute regimes (in which the particle backreaction on the fluid is small) or on highly concentrated ones (in which the discrete nature of the particles is immaterial). Additionally, most studies have focused on plumes in quiescent environments. In the present study, we investigate dense plumes falling in both quiescent and turbulent air. We drop size-selected microscopic particles into a jet-stirred chamber that generates a large region of homogeneous air turbulence. We measure the particle spatial distribution and velocity by means of time-resolved velocimetry and tracking techniques. This allows us to characterize the effect of ambient turbulence on the plume spread, concentration distribution, and fall speed. [Preview Abstract] |
Sunday, November 19, 2017 2:41PM - 2:54PM |
D6.00003: Direct simulation of fluid-structure interaction with Blue Richard V. Craster, Seungwon Shin, Jalel Chergui, Damir Juric, Lyes Kahouadji, Omar K. Matar The interaction of multiphase flows with complex solid geometries is directly simulated in {\it Blue} using a direct forcing technique (Fadlun, Verzicco, Orlandi \& Mohd-Yusof, JCP 161 (2000) 35-60) in the broader context of the immersed boundary method. This capability has recently been introduced in {\it Blue} which is a solver for massively-parallel simulations of fully three-dimensional multiphase flows. Arbitrary solid shapes can be constructed or introduced in CAD format. These solid objects can then be treated as either static, in forced translational and/or rotational motion or in fully free motion with full two-way coupling to the fluid phases. We study the benchmark case of a simple solid sphere plunging into a liquid pool. In addition we present examples of more complex moving solid objects and their interaction with liquid-gas free-surfaces. [Preview Abstract] |
Sunday, November 19, 2017 2:54PM - 3:07PM |
D6.00004: A multiphase approach to model ultrafiltration of deformable colloids Malavika Haribabu, Dave Dunstan, Malcolm Davidson, Dalton Harvie Ultrafiltration (UF) is widely used in the dairy industry to fractionate and concentrate proteins, during the manufacture of milk protein concentrate and cheese. The protein build-up, comprising casein micelles (CM) and whey proteins, at the membrane surface during UF increases the resistance of the membrane system, thereby decreasing the performance of the process unit. CM have a complex structure that hydrodynamically behaves as a hard-sphere when dilute, but deforms beyond the random packing limit, forming a shear-thinning gel. This study employs a mixture model, based on the mixture phase continuity, Navier-Stokes equations, and solids continuity equation, to predict the solid concentration and velocity distribution during UF of CM. Micelle deformation is modelled as a function of volume fraction and dependent on its elastic modulus and particle size. The effect of deformation on gel permeability is implemented via Happel's permeability for hard spheres. Under crossflow conditions, the gel thickness is observed to increase along the membrane length, followed by a decrease towards the end of the membrane, resulting in an increase in flux at the latter section of the membrane. This study demonstrates that the membrane end-effects are important in determining UF performance. [Preview Abstract] |
Sunday, November 19, 2017 3:07PM - 3:20PM |
D6.00005: CFD modelling of liquid-solid transport in the horizontal eccentric annuli. Sneha Sayindla, Niranjan Reddy challabotla In oil and gas drilling operations, different types of drilling fluids are used to transport the solid cuttings in an annulus between drill pipe and well casing. The inner pipe is often eccentric and flow inside the annulus can be laminar or turbulent regime. In the present work, Eulerian-Eulerian granular multiphase CFD model is developed to systematically investigate the effect of the rheology of the drilling fluid type (Newtonian and non-Newtonian), drill pipe eccentricity and inner pipe rotation on the efficiency of cuttings transport. Both laminar and turbulent flow regimes were considered. Frictional pressure drop is computed and compared with the flow loop experimental results reported in the literature. The results confirm that the annular frictional pressure loss in a fully eccentric annulus are significantly lesser than the concentric annulus. Inner pipe rotation improve the efficiency of the cuttings transport in laminar flow regime. Cuttings transport velocity and concentration distribution were analysed to predict the different flow patterns such as stationary bed, moving bed, heterogeneous and homogeneous bed formation. [Preview Abstract] |
Sunday, November 19, 2017 3:20PM - 3:33PM |
D6.00006: Dispersal of Rock and Coal Particles Produced by a Moving Shock Wave Shuyue Lai, Ryan Houim, Elaine Oran Numerical simulations of a shock wave passing over a thin layer of dust particles were performed using an unsteady multidimensional compressible model. The model takes into account multiple types of particle by using a binning approach. Particles in each bin have their own uniform particle type and diameter. The model solves one set of Euler equations for the gas phase and N sets of Euler equations for N particle phases. Sets of the governing equations are coupled with each other through the effects of drag, lift, etc. Specifically, we performed simulations of dispersal of coal- and rock-dust particles under the action of a Mach 1.4 shock wave in which the coal- and rock-dust particles are uniformly mixed. The rock and coal particles have a density of 2500 kg/m$^3$ and 1300 kg/m$^3$, and a diameter of 80 $\mu$m and 10 $\mu$m, respectively. The results show that the particle dispersal depends on both the size and density. Particles with small moment of inertia tend to follow the gas flow, while particles with larger moment of inertia experience a larger vertical lifting force. In addition, we performed the simulations where a thin layer of rock-dust was placed on top of a thicker layer of coal-dust and studied the effect of the rock dust on suppressing the coal-dust lifting. [Preview Abstract] |
Sunday, November 19, 2017 3:33PM - 3:46PM |
D6.00007: Numerical investigation of adhesion effects on solid particles filtration efficiency Amira Shaffee, Paul Luckham, Omar K. Matar Our work investigate the effectiveness of particle filtration process, in particular using a fully-coupled Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM) approach involving poly-dispersed, adhesive solid particles. We found that an increase in particle adhesion reduces solid production through the opening of a wire-wrap type filter. Over time, as particle agglomerates continuously deposit on top of the filter, layer upon layer of particles is built on top of the filter, forming a particle pack. It is observed that with increasing particle adhesion, the pack height build up also increases and hence decreases the average particle volume fraction of the pack. This trend suggests higher porosity and looser packing of solid particles within the pack with increased adhesion. Furthermore, we found that the pressure drop for adhesive case is lower compared to non-adhesive case. Our results suggest agglomerating solid particles has beneficial effects on particle filtration. One important application of these findings is towards designing and optimizing sand control process for a hydrocarbon well with excessive sand production which is major challenge in oil and gas industry. [Preview Abstract] |
Sunday, November 19, 2017 3:46PM - 3:59PM |
D6.00008: Mach number and particle size effects on unsteady drag of microparticles behind a shock wave Ankur Bordoloi, Adam Martinez, Kathy Prestridge The physics underlying to the unsteady drag of shock accelerated microparticles through the relaxation zone remain mysterious due to the lack of models that are relevant over length and time scales larger than the acoustic times. Experiments at the Horizontal Shock Tube (HST) have shown that the time dependent drag coefficient, C$_{\mathrm{D}}$(t) of a microparticle behind a shock wave can rise to orders of magnitude larger than values predicted by existing quasi-steady and unsteady drag models. In this presentation, we will extend our investigation by probing the sensitivity of drag to particle size and shock Mach number. The particle displacement relative to the shock is optically measured in the HST using high-speed microscopic Particle Tracking Velocimetry (PTV) synchronized with a shadowgraph system. The challenge of in-situ dynamic size measurement is overcome by using a Phase Doppler Particle Analyzer (PDPA). Time dependent drag coefficient is obtained by analyzing about 50 trajectories for incident Mach numbers, Ms $=$ 1.2, 1.3, 1.4 and 1.5. With finer temporal resolution and more accurate particle size measurement than before, we will show that the early post-shock relaxation phase is Mach-sensitive in a systematic way before the particle relaxes to the post-shock gas velocity. [Preview Abstract] |
Sunday, November 19, 2017 3:59PM - 4:12PM |
D6.00009: A kinetic-based hyperbolic two-fluid model for fully compressible particle-laden flows Rodney O. Fox Starting from coupled Boltzmann--Enskog kinetic equations for a two-particle system consisting of elastic rigid spheres, a hyperbolic two-fluid model for fully compressible particle-laden flows is derived. The kinetic equations account for particle--particle collisions, the Archimedes force due to pressure gradients in each phase, the added-mass force and a dispersion force. For simplicity, the particles in a given phase are assumed to have identical mass and volume, and no internal degrees of freedom. The compressible gas phase is obtained in the limit where the particle volume in one phase tends to zero with fixed phase density. The moment systems resulting from the two kinetic equations are closed at second order by invoking the anisotropic Gaussian closure. The resulting two-fluid model consists of transport equations for the mass, mean momentum and a symmetric, second-order, kinetic energy tensor for each phase. By explicitly computing the eigenvalues of the flux matrix, it is demonstrated that the model is hyperbolic when any combination of drag, buoyancy, added mass and/or dispersion. [Preview Abstract] |
Sunday, November 19, 2017 4:12PM - 4:25PM |
D6.00010: Migration of rigid particles in two-phase viscoelastic shear flow Patrick Anderson, Nick Jaensson, Martien Hulsen We present simulations of particle migration in two-phase flows, where one of the fluids is viscoelastic, whereas the other is Newtonian. The fluid-fluid interface is assumed to be diffuse, and is described using Cahn-Hilliard theory. The equations are solved using the finite element method on moving meshes that are aligned with the particle boundary. The meshes used are highly refined in the interfacial region between the fluids and near the particle boundary, which allows us to perform simulations with a small interfacial thickness. Four regimes of particle migration are observed. The first regime, migration away from the interface, occurs if normal stresses in the viscoelastic fluid are absent, i.e. a Newtonian fluid. Due to the deformation of the interface, as Laplace pressure is build up, effectively pushing the particle away from the interface. The second regime, halted migration, occurs if the particle migrates toward the interface, but the migration is halted due to the Laplace pressure. In the third regime, interface penetration, the interfacial tension is not large enough to halt the migration, and the particle moves into the Newtonian fluid, encapsulated by a film of viscoelastic fluid. In the final fourth regime the particles are adsorbed at the interface. [Preview Abstract] |
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