Effects of Flow Velocity and Particle Size on Soot Penetration Depth determined by Competition of Bridge Formation

Dispersion characteristics are important factors affecting groundwater solute transport in porous media. In marine environments, solute dispersion leads to the formation of freshwater aquifers under islands. In this study, a series of model tests were designed to explore the relationship between the dispersion characteristics of solute in calcareous sands and the particle size, degree of compactness, and gradation of porous media, with a discussion of the types of dispersion mechanisms in coral sands. It was found that the particle size of coral sands was an important parameter affecting the dispersion coefficient, with the dispersion coefficient increasing with particle size. Gradation was also an important factor affecting the dispersion coefficient of coral sands, with the dispersion coefficient increasing with increasing d10. The dispersion coefficient of coral sands decreased approximately linearly with increasing compactness. The rate of decrease was −0.7244 for single-grained coral sands of particle size 0.25–0.5 mm. When the solute concentrations and particle sizes increased, the limiting concentration gradients at equilibrium decreased. In this study, based on the relative weights of molecular diffusion versus mechanical dispersion under different flow velocity conditions, the dispersion mechanisms were classified into five types, and for each type, a corresponding flow velocity limit was derived.

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Comparison of mechanical disturbance in soft sediments due to tickler-chain SumWing trawl vs. electro-fitted PulseWing trawl

ICES Journal of Marine Science ◽

10.1093/icesjms/fsy124 ◽

2018 ◽

Vol 76 (1) ◽

pp. 312-329 ◽

Cited By ~ 14

Author(s):

Jochen Depestele ◽

Koen Degrendele ◽

Moosa Esmaeili ◽

Ana Ivanović ◽

Silke Kröger ◽

...

Keyword(s):

Particle Size ◽

Penetration Depth ◽

Particle Size Analysis ◽

Size Analysis ◽

Strength Analysis ◽

Sediment Profile ◽

Soft Sediments ◽

Sediment Layers ◽

Micro Topography ◽

Seabed Roughness

Abstract Tickler-chain SumWing and electrode-fitted PulseWing trawls were compared to assess seabed impacts. Multi-beam echo sounder (MBES) bathymetry confirmed that the SumWing trawl tracks were consistently and uniformly deepened to 1.5 cm depth in contrast to 0.7 cm following PulseWing trawling. MBES backscatter strength analysis showed that SumWing trawls (3.11 dB) flattened seabed roughness significantly more than PulseWing trawls (2.37 dB). Sediment Profile Imagery (SPI) showed that SumWing trawls (mean, SD) homogenised the sediment deeper (3.4 cm, 0.9 cm) and removed more of the oxidised layer than PulseWing trawls (1 cm, 0.8 cm). The reduced PulseWing trawling impacts allowed a faster re-establishment of the oxidised layer and micro-topography. Particle size analysis suggested that SumWing trawls injected finer particles into the deeper sediment layers (∼4 cm depth), while PulseWing trawling only caused coarsening of the top layers (winnowing effect). Total penetration depth (mean, SD) of the SumWing trawls (4.1 cm, 0.9 cm) and PulseWing trawls (1.8 cm, 0.8 cm) was estimated by the depth of the disturbance layer and the layer of mobilized sediment (SumWing = 0.7 cm; PulseWing trawl = 0.8 cm). PulseWing trawls reduced most of the mechanical seabed impacts compared to SumWing trawls for this substrate and area characteristics.

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The Rule of Carrying Cuttings in Horizontal Well Drilling of Marine Natural Gas Hydrate

Energies ◽

10.3390/en13051129 ◽

2020 ◽

Vol 13 (5) ◽

pp. 1129 ◽

Cited By ~ 2

Author(s):

Na Wei ◽

Yang Liu ◽

Zhenjun Cui ◽

Lin Jiang ◽

Wantong Sun ◽

...

Keyword(s):

Particle Size ◽

Flow Velocity ◽

Gas Hydrate ◽

Horizontal Well ◽

Drilling Fluid ◽

Test Method ◽

Critical Flow ◽

Fluid Density ◽

Critical Flow Velocity ◽

Orthogonal Test Method

Horizontal well drilling is a highly effective way to develop marine gas hydrate. During the drilling of horizontal wells in the marine gas hydrate layer, hydrate particles and cutting particles will migrate with the drilling fluid in the horizontal annulus. The gravity of cuttings is easy to deposit in the horizontal section, leading to the accumulation of cuttings. Then, a cuttings bed will be formed, which is not beneficial to bring up cuttings and results in the decrease of wellbore purification ability. Then the extended capability of the horizontal well will be restricted and the friction torque of the drilling tool will increase, which may cause blockage of the wellbore in severe cases. Therefore, this paper establishes geometric models of different hole enlargement ways: right-angle expansion, 45-degree angle expansion, and arc expanding. The critical velocity of carrying rock plates are obtained by EDEM and FLUENT coupling simulation in different hydrate abundance, different hydrate-cuttings particle sizes and different drilling fluid density. Then, the effects of hole enlargement way, particle size, hydrate abundance and drilling fluid density on rock carrying capacity are analyzed by utilizing an orthogonal test method. Simulation results show that: the critical flow velocity required for carrying cuttings increases with the increase of the particle size of the hydrate-cuttings particle when the hydrate abundance is constant. The critical flow velocity decreases with the increase of drilling fluid density, the critical flow velocity carrying cuttings decreases with the increase of hydrate abundance when the density of the drilling fluid is constant. Orthogonal test method was used to evaluate the influence of various factors on rock carrying capacity: hydrate-cuttings particle size > hole enlargement way > hydrate abundance > drilling fluid density. This study provides an early technical support for the construction parameter optimization and well safety control of horizontal well exploitation models in a marine natural gas hydrate reservoir.

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Effect of Abrasive Particle Size on Lapping of Sapphire Wafer by Fixed Abrasive Pad

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.764.106 ◽

2018 ◽

Vol 764 ◽

pp. 106-114

Author(s):

Jian Bin Wang ◽

Zhen Li ◽

Yong Wei Zhu ◽

Ben Chi Jiang ◽

Pei Cheng Shi

Keyword(s):

Particle Size ◽

Penetration Depth ◽

Material Removal ◽

Removal Rate ◽

Abrasive Particle ◽

Work Piece ◽

Average Surface Roughness ◽

Sapphire Wafer ◽

Fixed Abrasive Pad ◽

Fixed Abrasive

The choice of abrasive particle size is crucial to improve the lapping efficiency and surface quality in lapping of sapphire wafer by fixed abrasive (FA) pad. A model for the penetration depth of a single abrasive is developed with fixed abrasive pad. A serious of lapping tests were carried out using FA pads embedded with different size of diamond particles to verify the validity of the developed model. Results show that the penetration depth of abrasive is related not only to the particle size, but to the hardness ratio of the work-piece to the pad as well. The material removal rate of sapphire is proportional to the square of abrasive particle size, while the average surface roughness is proportional to the abrasive particle size.

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Suppressing the Use of Critical Raw Materials in Joining of AISI 304 Stainless Steel Using Activated Tungsten Inert Gas Welding

Metals ◽

10.3390/met9111187 ◽

2019 ◽

Vol 9 (11) ◽

pp. 1187 ◽

Cited By ~ 2

Author(s):

Sebastian Balos ◽

Miroslav Dramicanin ◽

Petar Janjatovic ◽

Ivan Zabunov ◽

Branka Pilic ◽

...

Keyword(s):

Particle Size ◽

Penetration Depth ◽

Marangoni Convection ◽

Raw Materials ◽

Oxide Particle ◽

Inert Gas ◽

304 Stainless Steel ◽

Welding Condition ◽

Aisi 304 ◽

Critical Raw Materials

The aim of this study was to study the influence of TiO2 coating for its efficacy during the activated-tungsten inert gas (TIG) welding and to suppress the use of consumables that are rich in critical raw materials. Post-welding penetration depth, particle size distribution, microstructure, and microhardness of welded samples were assessed. Based on these results, it was found that there is no direct correlation between the weld metal surface area and the coating. The particle size in the coating, although, seemed to have played an important role, e.g., nanoparticles resulted in an increased penetration depth and depth/width (D/W) ratio as opposed to the submicron-sized particles. The most optimal welding condition resulted when a mixture of submicron-sized and nanometric-sized particles were used. It was demonstrated by the Zeta analyser results that the micron particles rub the nanoparticles due to mechanical friction resulting in smaller oxide particle formation in the coating. Finally, the presence of Marangoni convection in TIG and reversed Marangoni convection in the activated TIG (A-TIG) process were proven by means of the microstructure analysis and measurement, which were found to be positively correlated.

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A Study on the Non-Saturated Concrete of Subsea Tunnel

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.170-173.1618 ◽

2012 ◽

Vol 170-173 ◽

pp. 1618-1624

Author(s):

Xin Jiang Wei ◽

Yuan Zhu Zhang ◽

Xiao Zhen Li

Keyword(s):

Flow Velocity ◽

Penetration Depth ◽

Relative Permeability ◽

Water Pressure ◽

Seepage Velocity ◽

Theoretical Derivation ◽

Water Seepage ◽

Strength Grade ◽

Subsea Tunnel ◽

Saturated Concrete

The objective of this study is to investigate the water seepage in unsaturated concrete under pressure through theoretical derivation. To establish the theoretical mode of water pressure and seepage velocity various with location and time. Finally, a formula about penetration depth is derived. And it is more practical. Meanwhile, analysis is made about the effect of the water pressure, the strength grade, permeability and relative permeability and other factors on the flow velocity and penetration depth.

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