scholarly journals Simulated and Experimental Study of Sediments Sampling Parameters Based on the VOF Method

2020 ◽  
Author(s):  
Shudong He ◽  
YouDuo Peng ◽  
Yongping Jin ◽  
Jian Yan ◽  
Buyan Wan
Keyword(s):  
Numerical Simulation ◽  
Real World ◽  
Dynamic Viscosity ◽  
Vof Method ◽  
Tube Diameter ◽  
Drainage Area ◽  
Sampling Tube ◽  
Simulation Results ◽  
Seabed Sediments ◽  
Penetration Velocity

Abstract Sediments in the seabed hold vital clues to the study of marine geology, microbial communities and history of ocean life, and the remote operated vehicle (ROV) mounted tubular sampling is an important way to obtain sediments. However, sampling in the seabed is a particularly difficult and complicated task due to the difficulty accessing deep water layers. The sampling is affected by the sampler’s structural parameters, operation parameters and the interaction between the sampling tube and sediments, which usually results in low volume and coring rate of sediments obtained. This paper simulated the soft viscous seabed sediments as non-Newtonian Herschel-Bulkley viscoplastic fluids and established a numerical model for the tubular sampling based on the volume of fluid (VOF) method. The influence rules of the sampling tube diameter, drainage area rate, penetration velocity, and sediments dynamic viscosity on coring rate and volume were studied. The results showed that coring volume was negatively correlated with all the parameters except the sampling tube diameter. Furthermore, coring rate decreased with increases in penetration velocity, drainage area rate, and sediments dynamic viscosity. The coring rate first increased and then decreased with increasing of the sampling tube diameter, and the peak value was also influenced by penetration velocity. Then, based on the numerical simulation results, an experimental sampling platform was set up and real-world sampling experiments were conducted. The simulation results tallied with the experimental results, with a maximum absolute error of only 4.6%, which verified that the numerical simulation model accurately reflected real-world sampling. The findings in this paper can provide a theoretical basis for facilitating the optimal design of the geometric structure of the seabed sediments samplers and the parameters in the sampling process.

scholarly journals Numerical Simulation and Experimental Study of a Sediment Sampler Sampling Based on VOF Method

2020 ◽  
Author(s):  
Shudong He ◽  
YouDuo Peng ◽  
Yongping Jin ◽  
Buyan Wan
Keyword(s):  
Numerical Simulation ◽  
Dynamic Viscosity ◽  
Maximum Error ◽  
Viscoplastic Fluid ◽  
Computational Fluid Mechanics ◽  
Sampling Device ◽  
Sampling Tube ◽  
Sampling Volume ◽  
Simulation Results ◽  
Volume Method

Abstract This paper takes the full-ocean-depth sampling device of the mechanical hand-held sampler as the research object, simulates the soft viscous sediment as non-Newtonian Herschel Bulkley viscoplastic fluid, uses the finite volume method and applies the computational fluid mechanics software Fluent to establish the sediment sampling model.VOF method is used to track multiphase flow interface. The effects of the sampling speed, diameter of the sampling tube, drainage discharge and sediment dynamic viscosity on coring rate and sampling volume are studied. The results show that the sampling volume is negatively correlated with those influencing factors. However, the coring rate decreases with the increase of sampling speed, drainage area ratio at inlet and outlet, and dynamic viscosity of sediment. The coring rate first increases and then decreases with the increase of the diameter of the sampling tube, and the peak value is related to the sampling speed and tube diameter. Then, based on the analysis of the numerical simulation results, a sampling simulation experimental platform is built and the sampling experiment is carried out. It can be concluded that the simulation results tally with the experimental results, with the maximum error being only -4.6%, which further verifies the correctness of the numerical model.

Investigation on penetration model of shaped charge jet in water

2016 ◽  
Vol 30 (02) ◽  
pp. 1550268 ◽  
Author(s):  
Jinwei Shi ◽  
Xingbai Luo ◽  
Jinming Li ◽  
Jianwei Jiang
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Model Simulation ◽  
Theoretical Models ◽  
Theoretical Research ◽  
Water Medium ◽  
Simulation Results ◽  
Jet Penetration ◽  
The Impact ◽  
Penetration Velocity

To analyze the process of jet penetration in water medium quantitatively, the properties of jet penetration spaced target with water interlayer were studied through test and numerical simulation. Two theoretical models of jet penetration in water were proposed. The theoretical model 1 was established considering the impact of the shock wave, combined with the shock equation Rankine–Hugoniot and the virtual origin calculation method. The theoretical model 2 was obtained by fitting theoretical analysis and numerical simulation results. The effectiveness and universality of the two theoretical models were compared through the numerical simulation results. Both the models can reflect the relationship between the penetration velocity and the penetration distance in water well, and both the deviation and stability of theoretical model 1 are better than 2, the lower penetration velocity, and the larger deviation of the theoretical model 2. Therefore, the theoretical model 1 can reflect the properties of jet penetration in water effectively, and provide the reference of model simulation and theoretical research.

scholarly journals Cold Ironing Galvanic Corrosion Issues with Regard to a Shore-to-Ship Medium Voltage Connection

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5372
Author(s):  
Maciej Kozak ◽  
Jarosław Chmiel
Keyword(s):  
Numerical Simulation ◽  
Reinforced Concrete ◽  
Real World ◽  
Power Supply ◽  
Galvanic Corrosion ◽  
Combustion Engines ◽  
Medium Voltage ◽  
Real World Applications ◽  
Concrete Degradation ◽  
Simulation Results

Cold ironing refers to the usage of less polluting power supply sources to deliver electricity to the moored ship. Such a shore-to-ship system is used when the ship is at a port so the auxiliary combustion engines may be turned off. This paper presents the numerical simulation results of a medium voltage cold-ironing system with regard to the currents flowing between the ship’s hull and grounding busbar. The IT electrical inland system with a neutral grounding resistor, as commonly used in shore-to-ship systems, is investigated. Parasitic capacitances present between the phase-to-hull and phase-to-ground in real-world applications can vary from each other. The direct and alternating currents flowing across the hull, seawater and the pier structure are amongst the causes that can lead to premature reinforced concrete degradation. Chosen cases of phase-to-ground or hull unequal capacitances influencing AC stray currents were considered.

Three-Dimensional Numerical Simulation of the Hydraulic Characteristics of Spillway in Gushitan Reservoir

2012 ◽  
Vol 256-259 ◽  
pp. 2403-2406
Author(s):  
Shu Guang Jing ◽  
Xue Ping Gao ◽  
Lai Fei Jia ◽  
Li Ping Xu
Keyword(s):  
Numerical Simulation ◽  
Water Surface ◽  
Three Dimensional ◽  
Simulation Method ◽  
Vof Method ◽  
Hydraulic Characteristics ◽  
Bottom Pressure ◽  
Surface Profiles ◽  
Simulation Results ◽  
Good Agreement

Based on standard k-ε turbulence model and the VOF method for tracking free surface, hydraulic characteristics of the spillway in Gushitan Reservoir are simulated with a 3-D numerical model. The discharge capacity, water surface profiles, bottom pressure distribution and flow pattern are studied. Numerical simulation results have been in good agreement with experimental results, showing fine feasibility to study hydraulic characteristics of the spillway with the VOF method. The hydraulic characteristics acquired by the numerical simulation method can be used for spillway design.

Avalanche Features in Silicon Schottky-FETs in Accordance with Numerical Simulation Results

2006 ◽  
Vol 65 (16) ◽  
pp. 1533-1546
Author(s):  
Yu. Ye. Gordienko ◽  
S. A. Zuev ◽  
V. V. Starostenko ◽  
V. Yu. Tereshchenko ◽  
A. A. Shadrin
Keyword(s):  
Numerical Simulation ◽  
Simulation Results

Tail shapes lead to different propulsive mechanisms in the body/caudal fin undulation of fish

2020 ◽  
pp. 095440622096768
Author(s):  
Jialei Song ◽  
Yong Zhong ◽  
Ruxu Du ◽  
Ling Yin ◽  
Yang Ding
Keyword(s):  
Numerical Simulation ◽  
Aspect Ratio ◽  
High Efficiency ◽  
The Body ◽  
Caudal Fin ◽  
Fish Model ◽  
Swimming Efficiency ◽  
Simulation Results ◽  
Propulsive Mechanism ◽  
High Depth

In this paper, we investigate the hydrodynamics of swimmers with three caudal fins: a round one corresponding to snakehead fish ( Channidae), an indented one corresponding to saithe ( Pollachius virens), and a lunate one corresponding to tuna ( Thunnus thynnus). A direct numerical simulation (DNS) approach with a self-propelled fish model was adopted. The simulation results show that the caudal fin transitions from a pushing/suction combined propulsive mechanism to a suction-dominated propulsive mechanism with increasing aspect ratio ( AR). Interestingly, different from a previous finding that suction-based propulsion leads to high efficiency in animal swimming, this study shows that the utilization of suction-based propulsion by a high- AR caudal fin reduces swimming efficiency. Therefore, the suction-based propulsive mechanism does not necessarily lead to high efficiency, while other factors might play a role. Further analysis shows that the large lateral momentum transferred to the flow due to the high depth of the high- AR caudal fin leads to the lowest efficiency despite the most significant suction.

scholarly journals Experiment and simulation about the effect of wear-ring abrasion on the performance of a marine centrifugal pump

2021 ◽  
Vol 13 (2) ◽  
pp. 168781402199811
Author(s):  
Wu Xianfang ◽  
Du Xinlai ◽  
Tan Minggao ◽  
Liu Houlin
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Vibration Velocity ◽  
Test Results ◽  
Obvious Effect ◽  
Performance Change ◽  
Pump Test ◽  
Simulation Results ◽  
Axis Passing

The wear-ring abrasion can cause performance degradation of the marine centrifugal pump. In order to study the effect of front and back wear-ring clearance on a pump, test and numerical simulation were used to investigate the performance change of a pump. The test results show that the head and efficiency of pump decrease by 3.56% and 9.62% respectively at 1.0 Qd due to the wear-ring abrasion. Under 1.0 Qd, with the increase of the front wear-ring the vibration velocity at pump foot increases from 0.4 mm/s to 1.0 mm/s. The axis passing frequency (APF) at the measuring points increases significantly and there appears new characteristic frequency of 3APF and 4APF. The numerical simulation results show that the front wear-ring abrasion affects the flow at the inlet of the front chamber of the pump and impeller passage. And the back wear-ring abrasion has obvious effect on the flow in the back chamber of the pump and impeller passage, while the multi-malfunction of the front wear-ring abrasion and back wear-ring abrasion has the most obvious effect on the flow velocity and flow stability inside pump. The pressure pulsation at Blade Passing Frequency (BPF) of the three schemes all decrease with the increase of the clearance.

scholarly journals Development of Depth-Limited Wave Boundary Layers over a Smooth Bottom

2020 ◽  
Vol 9 (1) ◽  
pp. 27
Author(s):  
Hitoshi Tanaka ◽  
Nguyen Xuan Tinh ◽  
Xiping Yu ◽  
Guangwei Liu
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Boundary Layers ◽  
Wave Motion ◽  
Numerical Study ◽  
Experiment Data ◽  
Tidal Motion ◽  
Long Period ◽  
Simulation Results ◽  
Wave Boundary

A theoretical and numerical study is carried out to investigate the transformation of the wave boundary layer from non-depth-limited (wave-like boundary layer) to depth-limited one (current-like boundary layer) over a smooth bottom. A long period of wave motion is not sufficient to induce depth-limited properties, although it has simply been assumed in various situations under long waves, such as tsunami and tidal currents. Four criteria are obtained theoretically for recognizing the inception of the depth-limited condition under waves. To validate the theoretical criteria, numerical simulation results using a turbulence model as well as laboratory experiment data are employed. In addition, typical field situations induced by tidal motion and tsunami are discussed to show the usefulness of the proposed criteria.

Design of Impeller of Centrifugal Compressor for Water-Air Engine

2014 ◽  
Vol 496-500 ◽  
pp. 642-645
Author(s):  
Yun Wang ◽  
Wei Zhang
Keyword(s):  
Numerical Simulation ◽  
Power System ◽  
Centrifugal Compressor ◽  
Centrifugal Impeller ◽  
3D Design ◽  
Pump Impeller ◽  
Aero Engine ◽  
Simulation Results

In view of power system in water-air UAV requirements, combine with the centrifugal impeller for aero-engine and the pump impeller. The design of a impeller of centrifugal compressor can work on the air and in the water for the new concept of air-water engine. With 3D design and a 3D CFD solver on it and analysis the results of numerical simulation. Results show that the designed impeller successfully reached the goal on the air and in the water. The experiences accumulated in this procedure are useful for similar impeller aerodynamic designs.

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