Level Set interface treatment method is introduced into Euler method,which is employed for interface treatment method for multi-materials. Combined with the ghost fluid method,the moving interface is tracked. Fifth-or...Level Set interface treatment method is introduced into Euler method,which is employed for interface treatment method for multi-materials. Combined with the ghost fluid method,the moving interface is tracked. Fifth-order WENO spatial discretization and third-order TVD Runge-Kutta time discretization methods are used. Shock-wave action on bubble,implosion and velocity field Shock effect bubbles; implosion and velocity field are simulated by means of LS-MMIC3D programmed by C++. Nu-merical results show that the Level Set interface treatment method is effective and feasible for multi-material interface treatment in comparison with the WENO method.展开更多
In this paper,the dynamic characteristics of the bubble in a broken confined domain are studied.The broken confined domain is composed of a solid wall and a plate that has a hole.The axisymmetric numerical model is es...In this paper,the dynamic characteristics of the bubble in a broken confined domain are studied.The broken confined domain is composed of a solid wall and a plate that has a hole.The axisymmetric numerical model is established by combining the Eulerian finite-element method with volume of fluid(VOF)method,and is validated by comparing the results with those from an experiment.Then the influences of the wall distance,plate distance and size of the hole are analyzed.The results show that cavity-attraction jet caused by the hole and annular jet caused by the upper solid wall compete with each other to dominate the bubble dynamics.The cavity-attraction jet develops earlier,but slower.Thus,jet load in the bubble stage is mainly generated by the annular jet with a higher impact speed.Within a certain range,the closer the hole is to the bubble or the smaller the hole,the longer the pulsation period of the bubble will be.展开更多
n the area of naval architecture and ocean engineering,the research about the underwater xplosion problem is of great significance.To achieve prolonged simulation of near-free surface underwater explosion,the underwat...n the area of naval architecture and ocean engineering,the research about the underwater xplosion problem is of great significance.To achieve prolonged simulation of near-free surface underwater explosion,the underwater explosion transient numerical model is established in this paper based on compressible Eulerian finite element method(EFEM).Compared with Geers Hunter formula,EFEM is availably validated by simulating the free-field underwater xplosion case.Then,the bubble pulsation and flow field dynamic characteristics of the cases with different underwater explosive depth are compared in this work.Lastly,the height of the water hump and the pressure of flow flied are analyzed quantitatively through the simulation results.展开更多
The flotation process is a particle-hydrophobic surface-based separation technique. To improve the essential flotation steps of collision and attachment probabilities, and reduce the step of detachment probabilities b...The flotation process is a particle-hydrophobic surface-based separation technique. To improve the essential flotation steps of collision and attachment probabilities, and reduce the step of detachment probabilities between air bubbles and hydrophobic particles, a selectively designed cavitation venturi tube combined with a static mixer can be used to generate very high numbers of pico and nano bubbles in a flotation column. Fully embraced by those high numbers of tiny bubbles, hydrophobic particles readily attract the tiny bubbles to their surfaces. The results of column flotation of Pittsburgh No. 8 seam coal are obtained in a 5.08 cm ID and 162 cm height flotation column equipped with a static mixer and cavitation venturi tube, using kerosene as collector and MIBC as frother. Design of the experimental procedure is combined with a statistical two-stepwise analysis to determine the optimal operating conditions for maximum recovery at a specified grade. The effect of independent variables on the responses has been explained. Combustible material recovery of 85–90% at clean coal product of 10–11% ash is obtained from feed of 29.6% ash, with a much-reduced amount of frother and collector than that used in conventional column flotation. The column flotation process utilizing pico and nano bubbles can also be extended to the lower limit and upper limit of particle size ranges, minus 75 lm and 300–600 lm, respectively, for better recovery.展开更多
Based on the Cahn-Hilliard phase field model, a three-dimensional multiple-field coupling model for simulating the motion characteristics of a rising bubble in a liquid is established in a gas-liquid two-phase flow. T...Based on the Cahn-Hilliard phase field model, a three-dimensional multiple-field coupling model for simulating the motion characteristics of a rising bubble in a liquid is established in a gas-liquid two-phase flow. The gas-liquid interface motion is simulated by using a phase-field method, and the effect of the electric field intensity on bubble dynamics is studied without electric field, or with vertical electric field or horizontal electric field. Through the coupling effect of electric field and flow field, the deformation of a single rising bubble and the formation of wake vortices under the action of gravity and electric field force are studied in detail. The correctness of the results is verified by mass conservation, and the influences of different electric field directions and different voltages on the movement of bubbles in liquid are considered. The results show that the ratio of the length to axis is proportional to the strength of the electric field when the air bubble is stretched into an ellipsoid along the electric field line under the action of electrostatic gravity and surface tension. In addition, the bubble rising speed is affected by the electric field, the vertical electric field accelerates the bubble rise, and the horizontal direction slows it down.展开更多
为模拟生活中常见的流体现象,提出一种基于物理原理的气泡生成算法,并将应用于2种不可相溶流体模拟问题的VOF(volume of fluid)方法推广到任意多种不可相溶的流体模拟问题.在气泡生成算法中,通过调整模拟区域速度场的散度值,来模拟在气...为模拟生活中常见的流体现象,提出一种基于物理原理的气泡生成算法,并将应用于2种不可相溶流体模拟问题的VOF(volume of fluid)方法推广到任意多种不可相溶的流体模拟问题.在气泡生成算法中,通过调整模拟区域速度场的散度值,来模拟在气泡生成过程中由于液体和气体之间的状态转变导致的流体体积膨胀.在扩展的VOF方法中,使用物理学中的Skin-Onion方法将描述不同流体界面的多个VOF组合在一起,从而正确地描述任意多种流体问题.气泡生成和多种流体模拟的实验结果表明,采用文中方法可取得较好的视觉效果.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 10872085 and 10472042)Program for New Century Excellent Talents of Ministry of Education (Grant No. NCET-08-0043)+1 种基金National Basic Research Program of China (Grant No. 2010CB832700 6)Key Program of Numerical Simulation Key Laboratory of Sichuan Higher School (Grant No. 07NJZZ001)
文摘Level Set interface treatment method is introduced into Euler method,which is employed for interface treatment method for multi-materials. Combined with the ghost fluid method,the moving interface is tracked. Fifth-order WENO spatial discretization and third-order TVD Runge-Kutta time discretization methods are used. Shock-wave action on bubble,implosion and velocity field Shock effect bubbles; implosion and velocity field are simulated by means of LS-MMIC3D programmed by C++. Nu-merical results show that the Level Set interface treatment method is effective and feasible for multi-material interface treatment in comparison with the WENO method.
基金Project supported by the National Key Research and Development Program of China(Grant No.2018YFC0308900)the National Natural Science Foundation of China(Grant Nos.51879050,51925904).
文摘In this paper,the dynamic characteristics of the bubble in a broken confined domain are studied.The broken confined domain is composed of a solid wall and a plate that has a hole.The axisymmetric numerical model is established by combining the Eulerian finite-element method with volume of fluid(VOF)method,and is validated by comparing the results with those from an experiment.Then the influences of the wall distance,plate distance and size of the hole are analyzed.The results show that cavity-attraction jet caused by the hole and annular jet caused by the upper solid wall compete with each other to dominate the bubble dynamics.The cavity-attraction jet develops earlier,but slower.Thus,jet load in the bubble stage is mainly generated by the annular jet with a higher impact speed.Within a certain range,the closer the hole is to the bubble or the smaller the hole,the longer the pulsation period of the bubble will be.
基金The authors would like to acknowledge the support of the National Natural Science Foundation of China(Grant 11672081)the Industrial Technology Development Program(Grants JCKY2018604C010 and JCKY2017604C002).Finally,Thanks for the help of Zu-Hui Li during writing the paper.
文摘n the area of naval architecture and ocean engineering,the research about the underwater xplosion problem is of great significance.To achieve prolonged simulation of near-free surface underwater explosion,the underwater explosion transient numerical model is established in this paper based on compressible Eulerian finite element method(EFEM).Compared with Geers Hunter formula,EFEM is availably validated by simulating the free-field underwater xplosion case.Then,the bubble pulsation and flow field dynamic characteristics of the cases with different underwater explosive depth are compared in this work.Lastly,the height of the water hump and the pressure of flow flied are analyzed quantitatively through the simulation results.
基金provided by West Virginia State Coal and Energy Research Bureau (CERB)the Department of Mining Engineering,West Virginia University
文摘The flotation process is a particle-hydrophobic surface-based separation technique. To improve the essential flotation steps of collision and attachment probabilities, and reduce the step of detachment probabilities between air bubbles and hydrophobic particles, a selectively designed cavitation venturi tube combined with a static mixer can be used to generate very high numbers of pico and nano bubbles in a flotation column. Fully embraced by those high numbers of tiny bubbles, hydrophobic particles readily attract the tiny bubbles to their surfaces. The results of column flotation of Pittsburgh No. 8 seam coal are obtained in a 5.08 cm ID and 162 cm height flotation column equipped with a static mixer and cavitation venturi tube, using kerosene as collector and MIBC as frother. Design of the experimental procedure is combined with a statistical two-stepwise analysis to determine the optimal operating conditions for maximum recovery at a specified grade. The effect of independent variables on the responses has been explained. Combustible material recovery of 85–90% at clean coal product of 10–11% ash is obtained from feed of 29.6% ash, with a much-reduced amount of frother and collector than that used in conventional column flotation. The column flotation process utilizing pico and nano bubbles can also be extended to the lower limit and upper limit of particle size ranges, minus 75 lm and 300–600 lm, respectively, for better recovery.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51661020,11504149,and 11364024)the Postdoctoral Science Foundation of China(Grant No.2014M560371)the Funds for Distinguished Young Scientists of Lanzhou University of Technology,China(Grant No.J201304)
文摘Based on the Cahn-Hilliard phase field model, a three-dimensional multiple-field coupling model for simulating the motion characteristics of a rising bubble in a liquid is established in a gas-liquid two-phase flow. The gas-liquid interface motion is simulated by using a phase-field method, and the effect of the electric field intensity on bubble dynamics is studied without electric field, or with vertical electric field or horizontal electric field. Through the coupling effect of electric field and flow field, the deformation of a single rising bubble and the formation of wake vortices under the action of gravity and electric field force are studied in detail. The correctness of the results is verified by mass conservation, and the influences of different electric field directions and different voltages on the movement of bubbles in liquid are considered. The results show that the ratio of the length to axis is proportional to the strength of the electric field when the air bubble is stretched into an ellipsoid along the electric field line under the action of electrostatic gravity and surface tension. In addition, the bubble rising speed is affected by the electric field, the vertical electric field accelerates the bubble rise, and the horizontal direction slows it down.
文摘为模拟生活中常见的流体现象,提出一种基于物理原理的气泡生成算法,并将应用于2种不可相溶流体模拟问题的VOF(volume of fluid)方法推广到任意多种不可相溶的流体模拟问题.在气泡生成算法中,通过调整模拟区域速度场的散度值,来模拟在气泡生成过程中由于液体和气体之间的状态转变导致的流体体积膨胀.在扩展的VOF方法中,使用物理学中的Skin-Onion方法将描述不同流体界面的多个VOF组合在一起,从而正确地描述任意多种流体问题.气泡生成和多种流体模拟的实验结果表明,采用文中方法可取得较好的视觉效果.
