Bulletin of the American Physical Society
71st Annual Meeting of the APS Division of Fluid Dynamics
Volume 63, Number 13
Sunday–Tuesday, November 18–20, 2018; Atlanta, Georgia
Session G04: Non-dry Granular Flows |
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Chair: Eric Weeks, Emory University Room: Georgia World Congress Center B206 |
(Author Not Attending)
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G04.00001: Experimental and numerical study of the subaqueous granular dam-break flow Yi An, Wentao Zhang, Qingquan Liu Subaqueous granular flow is of great interesting in geophysics flow and coastal engineering. Despite its simple configuration, the underwater granular dam-break problem involves many mechanisms in a single event and thus could serve as a benchmark case for different numerical models. Here we carried out a series of experiments using the refractive index matching technique to obtain the motion of the spherical particle and the velocity field of the ambient liquid simultaneously. Then a three-dimensional two-phase continuum model is developed based on SedFOAM to simulate this high concentration granular flow. It is found that this dam-break granular flow could be divided into three regions including a liquid flow controlled surface, a slide dominated shallow layer beneath it, and a particle solid phase at the bottom. Thus, the dividing of the granular pressure, i.e. the permanent contact-induced component and the collision-induced component, is necessary for the numerical model to correctly represent the experimental data. |
Monday, November 19, 2018 10:48AM - 11:01AM |
G04.00002: Abstract Withdrawn
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Monday, November 19, 2018 11:01AM - 11:14AM |
G04.00003: Experimental and population balance modeling on spiral type Air Jet Mill: Batch milling Mahesh Maroti Dhakate, Devang V. Khakhar, Jyeshtharaj B. Joshi Jet milling is an energy-intensive process which is widely used in several industrial applications. In this research, experiments and population balance modeling have done to optimize the parameters like grinding pressure, milling residence time and hold-up to increase the performance of jet mill. This study investigates the effect of parameters on the flow pattern, particle concentration, median particle size and distribution and breakage yield through the experiments in a lab scale jet mill. In the visualization study, the concentration of particle is more in the peripheral region since the more collision occurs in the peripheral region produces reduced size particle and narrower size distribution. The fine median particle size and narrow size distribution are obtained with highest grinding pressure, milling residence time and lowest holdup. Breakage yield increases with an increase in grinding air pressure and milling time, and decreases with an increase in the holdup. From experiments and modeling, the particle size distribution becomes narrower with time and particle size decreases with time has observed. The experiments and modeling results optimize the grinding pressure, milling residence time and hold-up in the milling. |
Monday, November 19, 2018 11:14AM - 11:27AM |
G04.00004: Characterization of particle and heat losses of a lab-scale solid particle receiver Jesus Ortega, Peter V Vorobieff, Andrea Mammoli, Clifford Ho The solid particle receiver (SPR) developed at Sandia National Labs has been observed to experience mass and heat losses due to particle being ejected through the frontal aperture of the system. To further understand the impact on the receiver efficiency, particle image velocimetry (PIV), particle tracking velocimetry (PTV), and thermal imaging tools must be incorporated into the SPR for in-situ measurements. A lab-scale SPR has been developed to allow the design of controlled experiments to test the imaging equipment and tools. The lab-scale model operates with a 10 cm wide curtain with variable thickness (i.e. 0.1-1 cm), which drives discharge rate, and a controlled hot air supply which disrupts the curtain. The matrix of tests considers variables such as particle size, curtain thickness, particle and air temperature, air flow rate and direction. A 960-fps high-speed camera is used to capture the particles ejected from the system at high resolution and the advection corrected correlation image velocimetry (ACCIV) processing toolbox is being used to extract the particle velocity field as they leave the domain. For the thermal imaging measurements, an ImageIR8300 thermal camera with a 100 mm lens is used to estimate the temperature of the particle plumes. |
Monday, November 19, 2018 11:27AM - 11:40AM |
G04.00005: Investigations on Dielectric Particle Behaviors under the Effect of a Strong Electric Field Ran Tao, Shuiqing Li, Xianjun Yang Electrification and levitation of particles in an external electric field significantly influence the powder handling process. In this work, the behavior of polarized particles subjected to electrostatic forces induced by an external electric field is studied both experimentally and theoretically. In the experiment, two parallel electrodes are horizontally placed in a chamber with a well-controlled relative humidity. Dielectric particles of different diameters (from 150μm to 10μm) are then uniformly dispersed on the electrode below, which is connected to a dc voltage (from +3kV to +5kV). The particles are polarized and energized by the external electrostatic field. Various particle behaviors, including levitation, oscillation and formation of fractal agglomerates and straight particle chains, are observed under different conditions. Then we run simulations using adhesive Discrete Element Method (DEM), which well reproduces the experimental observations. Based on extensive numerical simulations, we propose simple criterions that allows one to determine the dominant behavior of particles in the system. |
Monday, November 19, 2018 11:40AM - 11:53AM |
G04.00006: The Effect of External Magnetic Fields on the Hall Effect of a Dusty Plasma Tornado Helena Gilbert Yoest, Sarah C Burnett, Daniel Perry Lathrop We present results from our experiment designed to characterize the way external magnetic fields influence the Hall Effect of a turbulent granular system, and we report on the measured voltage fluctuations. We agitated polystyrene particles in a vertical cylindrical annulus using a swirling flow of air, thus creating a model of a dusty plasma tornado. Because colliding particles lose or gain charge through the process of granular electrification, we observe a voltage difference between the concentric cylinders, confining the flow. The apparatus is placed inside of a vertical magnetic field of strength 0.62 T and aligned with the dipole. We observe a difference in voltage with varied strength of the magnetic field. The turbulent flow of collisionally charged particles produces a large fluctuation in voltage due to magnetic field. The nature of the spontaneous discharge produces random fluctuations, which are observed to be larger than the Hall Effect. This experiment has applications to systems undergoing granular electrification resulting in stochastic discharge. |
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