scholarly journals Rheology of three-phase suspensions determined via dam-break experiments

2021 ◽  
Vol 477 (2254) ◽  
Author(s):  
Janine Birnbaum ◽  
Einat Lev ◽  
Ed W. Llewellin
Keyword(s):  
Capillary Number ◽  
Relative Viscosity ◽  
Shear Thickening ◽  
Dam Break ◽  
Solid Particles ◽  
Rheological Models ◽  
Volcanic System ◽  
Three Phase ◽  
Inertial Regime

Three-phase suspensions, of liquid that suspends dispersed solid particles and gas bubbles, are common in both natural and industrial settings. Their rheology is poorly constrained, particularly for high total suspended fractions (≳0.5). We use a dam-break consistometer to characterize the rheology of suspensions of (Newtonian) corn syrup, plastic particles and CO 2 bubbles. The study is motivated by a desire to understand the rheology of magma and lava. Our experiments are scaled to the volcanic system: they are conducted in the non-Brownian, non-inertial regime; bubble capillary number is varied across unity; and bubble and particle fractions are 0 ≤  ϕ gas  ≤ 0.82 and 0 ≤  ϕ solid  ≤ 0.37, respectively. We measure flow-front velocity and invert for a Herschel–Bulkley rheology model as a function of ϕ gas , ϕ solid , and the capillary number. We find a stronger increase in relative viscosity with increasing ϕ gas in the low to intermediate capillary number regime than predicted by existing theory, and find both shear-thinning and shear-thickening effects, depending on the capillary number. We apply our model to the existing community code for lava flow emplacement, PyFLOWGO, and predict increased viscosity and decreased velocity compared with current rheological models, suggesting existing models may not adequately account for the role of bubbles in stiffening lavas.

scholarly journals Impact Force of a Geomorphic Dam-Break Wave against an Obstacle: Effects of Sediment Inertia

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 232
Author(s):  
Cristiana Di Cristo ◽  
Massimo Greco ◽  
Michele Iervolino ◽  
Andrea Vacca
Keyword(s):  
Impact Force ◽  
Dam Break ◽  
Solid Particles ◽  
Physical Damage ◽  
Two Phase ◽  
Rigid Obstacle ◽  
Shallow Water Approximation ◽  
Set Up ◽  
The Impact

The evaluation of the impact force on structures due to a flood wave is of utmost importance for estimating physical damage and designing adequate countermeasures. The present study investigates, using 2D shallow-water approximation, the morphodynamics and forces caused by a dam-break wave against a rigid obstacle in the presence of an erodible bed. A widely used coupled equilibrium model, based on the two-dimensional Saint–Venant hydrodynamic equations combined with the sediment continuity Exner equation (SVEM), is compared with a more complex two-phase model (TPM). Considering an experimental set-up presented in the literature with a single rigid obstacle in a channel, two series of tests were performed, assuming sand or light sediments on the bottom. The former test is representative of a typical laboratory experiment, and the latter may be scaled up to a field case. For each test, two different particle diameters were considered. Independently from the particle size, it was found that in the sand tests, SVEM performs similarly to TPM. In the case of light sediment, larger differences are observed, and the SVEM predicts a higher force of about 26% for both considered diameters. The analysis of the flow fields and the morphodynamics shows these differences can be essentially ascribed to the role of inertia of the solid particles.

Natural Convective Heat Transfer of Water-in-FC72 Nanoemulsion Fluids

2008 ◽  
Author(s):  
Zenghu Han ◽  
Bao Yang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Hydrodynamic Interaction ◽  
Convective Heat Transfer Coefficient ◽  
Relative Viscosity ◽  
Solid Particles ◽  
Water Loading

The use of SOLID-particles has long been a common way of increasing fluid thermal conductivity. In this paper, nanoemulsion fluids—dispersions of LIQUID-nanodroplets—are proposed. As an example, water-in-FC72 nanoemulsion fluids are developed, and their thermophysical properties and impact on natural convective heat transfer are investigated experimentally. A significant increase in thermal conductivity—up to 52% for 12vol% of water nanodroplets (or 7.1 wt%)—is observed in the fluids. The enhancement in conductivity and viscosity of the fluids is found to be nonlinear with water loading, indicating an important role of the hydrodynamic interaction and aggregation of nanodroplets. However, the relative viscosity is found to be about two times the relative conductivity if compared at the same water loading. The presence of water nanodroplets is found to systematically increase the natural convective heat transfer coefficient in these fluids, in contrast to the observation in several conventional nanofluids containing solid nanoparticles.

scholarly journals EEG Correlates of Old/New Discrimination Performance Involving Abstract Figures and Non-Words

2021 ◽  
Vol 11 (6) ◽  
pp. 719
Author(s):  
Monika Toth ◽  
Anke Sambeth ◽  
Arjan Blokland
Keyword(s):  
Recognition Memory ◽  
Current Knowledge ◽  
Discrimination Performance ◽  
Correct Identification ◽  
Memory Strength ◽  
Verbal Stimuli ◽  
Brain Responses ◽  
Three Phase ◽  
New Item

The processing of pre-experimentally unfamiliar stimuli such as abstract figures and non-words is poorly understood. Here, we considered the role of memory strength in the discrimination process of such stimuli using a three-phase old/new recognition memory paradigm. Memory strength was manipulated as a function of the levels of processing (deep vs. shallow) and repetition. Behavioral results were matched to brain responses using EEG. We found that correct identification of the new abstract figures and non-words was superior to old item recognition when they were merely studied without repetition, but not when they were semantically processed or drawn. EEG results indicated that successful new item identification was marked by a combination of the absence of familiarity (N400) and recollection (P600) for the studied figures. For both the abstract figures and the non-words, the parietal P600 was found to differentiate between the old and new items (late old/new effects). The present study extends current knowledge on the processing of pre-experimentally unfamiliar figurative and verbal stimuli by showing that their discrimination depends on experimentally induced memory strength and that the underlying brain processes differ. Nevertheless, the P600, similar to pre-experimentally familiar figures and words, likely reflects improved recognition memory of meaningless pictorial and verbal items.

Turnover among medical clowns early in their career

2021 ◽  
Vol 30 (2) ◽  
pp. 106-116
Author(s):  
Abira Reizer ◽  
Meni Koslowsky ◽  
Rivki Antilevich-Steg
Keyword(s):  
Job Satisfaction ◽  
Individual Differences ◽  
Traumatic Experiences ◽  
Mediating Role ◽  
Humor Appreciation ◽  
Three Phase ◽  
Research Findings ◽  
Turnover Behavior ◽  
Actual Turnover

In recent years, several investigations of the medical clowning profession have appeared in the literature. However, few studies have focused on factors associated with turnover among medical clowns early in their careers. The current study examined whether individual differences in humor disposition predicted turnover behavior. Participants were 111 medical clowns in a three-phase longitudinal study. Humor disposition was measured in the first week of their training, clowns' job satisfaction two months later, and turnover six months after that. Results showed that humor appreciation decreased actual turnover through the mediating role of job satisfaction, whereas individual differences in humor creation directly decreased turnover. In addition, previous traumatic experiences moderated the associations between humor appreciation and turnover. Overall, our research findings support the notion that humor disposition can help predict which clowns remain in the hospital.

scholarly journals Pickering emulsions stabilized by colloidal surfactants: Role of solid particles

Particuology ◽  
2021 ◽  
Author(s):  
Zhu Sun ◽  
Xiaoxiao Yan ◽  
Yao Xiao ◽  
Lingjie Hu ◽  
Max Eggersdorfer ◽  
...  
Keyword(s):  
Solid Particles ◽  
Pickering Emulsions

scholarly journals Effect of nano-solid particles on the mechanical properties of shear thickening fluid (STF) and STF-Kevlar composite fabric

2021 ◽  
Vol 16 ◽  
pp. 155892502110448
Author(s):  
Mingmei Zhao ◽  
Jinqiu Zhang ◽  
Zhizhao Peng ◽  
Jian Zhang
Keyword(s):  
Mechanical Properties ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Tensile Force ◽  
Shear Thickening ◽  
Solid Particles ◽  
Time Range ◽  
Shear Thickening Fluid ◽  
Pull Out ◽  
Diamond Particles

To analyze the effect of nano-solid particles on the mechanical properties of shear thickening fluid (STF) and its Kevlar composite fabric. In this study, nano-silica and polyethylene glycol (PEG 200) were used as dispersed and continuous phases. Nano-graphite and nano-diamond particles were used as additives to prepare STF and Kevlar composite fabric. Study the friction characteristics and rheological characteristics of STF at different temperatures. Explore the STF’s mechanical response under transient high-speed impact conditions through the split Hopkinson pressure bar experiment. The mechanical properties of STF-Kevlar fabric are studied through yarn pull-out test and burst experiments. The experimental results show that the intermolecular repulsive force of STF is enhanced under a high-temperature environment, and shear thickening effect is reduced. Nano-diamond particles strengthen the contact coupling force and contact probability between the particle clusters, so that the maximum viscosity of the system reaches 1679 Pa s, the thickening ratio reaches 318 times, and the rheological properties of the shear thickening fluid are improved. The results of the SHPB experiment show that the STF can complete a dynamic response within a 50–75 µs time range, and the maximum stress can reach 78 MPa. The bullet’s incident kinetic energy is not only transformed into thermal energy and phase change energy of solid-liquid conversion, but also into frictional energy between particles. The mechanical experiments of STF-Kevlar composite fabrics show that the tensile force value of STF5-Kevlar is the largest (10.3 N/13.5 N), and the tensile force of neat Kevlar was the smallest (4.3 N/4.9 N). The maximum bearing capacity (0.3 kN) and absorption energy (51.8 J) of Neat Kevlar are less than those of STF1-Kevlar (3.2 kN, 116.7 J) and STF3-Kevlar (1.9 kN, 88.2 J), and STF5-Kevlar (4.7 kN, 143.3 J). Fabric’s failure mode is converted from partial yarn extraction to overall deformation and rupture of the fabric. Therefore, by changing the solid additives’ parameters, the STF and the composite fabric’s mechanical properties can be effectively controlled, which provides a reference for preparing the STF and fabric composite materials.

scholarly journals Luther and Norwegian Nation-Building

Nordlit ◽  
2019 ◽  
Author(s):  
Anders Aschim
Keyword(s):  
19Th Century ◽  
Nation Building ◽  
National Discourse ◽  
Phase Development ◽  
Three Phase ◽  
The Reformation ◽  
The 19Th Century

In most Protestant countries, the Reformation was closely connected to the development of vernacular languages and literatures. In Norway under Danish rule, this was not the case. Only in the 19th century, during the nation-building period of independent Norway, a Norwegian ecclesiastical language was developed. Some authors claim that this completed the Reformation in Norway – a protracted Reformation indeed. Particularly important were the hymns of Magnus Brostrup Landstad and Elias Blix. This study examines the role of Luther in the Norwegian 19th century national discourse, suggesting a three-phase development: Luther as text, as inspiration, and as argument. The full-blown use of Luther as argument was taken up by proponents of a nynorsk ecclesiastical language only during the final years of the Swedish-Norwegian union, just before its dissolution in 1905.

Mass transfer between solid particles and liquid in a three phase fluidized bed

1987 ◽  
Vol 65 (2) ◽  
pp. 228-236 ◽  
Author(s):  
A. Prakash ◽  
C. L. Briens ◽  
M. A. Bergougnou
Keyword(s):  
Mass Transfer ◽  
Fluidized Bed ◽  
Solid Particles ◽  
Three Phase
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