The volume fraction of the solid and liquid phase of debris flows,which evolves simultaneously across terrains,largely determines the dynamic property of debris flows. The entrainment process significantly influences ...The volume fraction of the solid and liquid phase of debris flows,which evolves simultaneously across terrains,largely determines the dynamic property of debris flows. The entrainment process significantly influences the amplitude of the volume fraction. In this paper,we present a depth-averaged two-phase debris-flow model describing the simultaneous evolution of the phase velocity and depth,the solid and fluid volume fractions and the bed morphological evolution. The model employs the Mohr–Coulomb plasticity for the solid stress,and the fluid stress is modeled as a Newtonian viscous stress. The interfacial momentum transfer includes viscous drag and buoyancy. A new extended entrainment rate formula that satisfies the boundary momentum jump condition(Iverson and Ouyang,2015) is presented. In this formula,the basal traction stress is a function of the solid volume fraction and can take advantage of both the Coulomb and velocity-dependent friction models. A finite volume method using Roe's Riemann approximation is suggested to solve the equations. Three computational cases are conducted and compared with experiments or previous results. The results show that the current computational model and framework are robust and suitable for capturing the characteristics of debris flows.展开更多
With the increase in mining depth, mine heat harm has appeared to be more prominent. The mine heat harm could be resolvedor reduced by ice refrigeration. Thus, ice transportation through pipeline becomes a critical pr...With the increase in mining depth, mine heat harm has appeared to be more prominent. The mine heat harm could be resolvedor reduced by ice refrigeration. Thus, ice transportation through pipeline becomes a critical problem; typically flowresistance occurs in the elbow. In the present study, according to the analysis of the surface morphology of fish scale, abiomimetic functional surface structure for the interior wall of elbow is designed. Based on the theory of liquid-solid two phaseflow, a CFD numerical simulation of ice-water mixture flowing through the elbow is carried out using finite element method.Conventional experiments of pressure drop and flow resistance for both bionic and common elbows are conducted to test theeffect of the bionic elbow on flow resistance reduction. It is found that with the increase in the ice mass fraction in the ice-watermixture, the effect of bionic elbow on resistance reduction becomes more obvious.展开更多
This paper presents an experimental study of the physical characteristic effects of large particles on hydraulic transport in a horizontal pipe.The particles are spherical and are large with respect to the diameter of...This paper presents an experimental study of the physical characteristic effects of large particles on hydraulic transport in a horizontal pipe.The particles are spherical and are large with respect to the diameter of the pipe(8%,10%,16% and 25%).Experiments were done to test the important parameters in solid transport(pressure,velocity,etc.).As a result,the relationship between the pressure gradient forces and the mixture velocity was substantially different from the pure liquid flow.However,in a single-phase flow a monotonous behavior of the pressure drop curve is observed,and the curve of the solid particle flow attains its minimum at the critical velocity.The regimes are characterized with differential pressure measurements and visualizations.展开更多
The samples of La8/9Sr1/45Na4/45MnO3(LSNMO)/x2(Sb2O3) were prepared by the solid-state reaction method. The electric transport properties and the temperature stability of magnetoresistance(MR) of the samples were stud...The samples of La8/9Sr1/45Na4/45MnO3(LSNMO)/x2(Sb2O3) were prepared by the solid-state reaction method. The electric transport properties and the temperature stability of magnetoresistance(MR) of the samples were studied through the measurements of X-ray diffraction patterns, resistivity–temperature(q–T) curves, mass magnetization– temperature(r–T) curves, and magnetoresistance–temperature(MR–T) curves. The results indicate that the q–T curves of the original material LSNMO show two peaks, and the phenomenon of two peaks of q–T curves disappears for the composite samples, which can be explained by a competition between surface-phase resistivity induced by boundarydependent scattering and body-phase resistivity induced by paramagnetism–ferromagnetism transition. For all the samples in the low temperature range, MR increases continuously with the decrease of temperature, which shows a characteristic of low-field magnetoresistance. However, MR basically keeps the same in the high temperature range. The paramagnetism–ferromagnetism transition is observed in the high temperature range due to a composite between perovskite manganite and insulator, which can enhance the temperature of MR appearance in the high temperature range and make it to appear near room temperature. For the sample with x = 0.12, MR remains constant at the value of 7.5 % in the temperature range of 300–260 K, which achieves a temperature stability of MR near room temperature. In addition,for the sample with x = 0.16, MR is above 6.8 % in the high temperature range of 318–252 K(DT = 66 K). MR almost remains constant in this temperature range, which favors the practical application of MR.展开更多
The transport properties of gluon in color space in a system of coexistence of both hadronic and QGP phases are investigated from the quantum transport equation of gluon.
基金Financial support from NSFC(Grant No.41572303,4151001059,41101008)Key Projects in the National Science & Technology Pillar Program(2014BAL05B01)CAS "Light of West China" Program
文摘The volume fraction of the solid and liquid phase of debris flows,which evolves simultaneously across terrains,largely determines the dynamic property of debris flows. The entrainment process significantly influences the amplitude of the volume fraction. In this paper,we present a depth-averaged two-phase debris-flow model describing the simultaneous evolution of the phase velocity and depth,the solid and fluid volume fractions and the bed morphological evolution. The model employs the Mohr–Coulomb plasticity for the solid stress,and the fluid stress is modeled as a Newtonian viscous stress. The interfacial momentum transfer includes viscous drag and buoyancy. A new extended entrainment rate formula that satisfies the boundary momentum jump condition(Iverson and Ouyang,2015) is presented. In this formula,the basal traction stress is a function of the solid volume fraction and can take advantage of both the Coulomb and velocity-dependent friction models. A finite volume method using Roe's Riemann approximation is suggested to solve the equations. Three computational cases are conducted and compared with experiments or previous results. The results show that the current computational model and framework are robust and suitable for capturing the characteristics of debris flows.
基金supported bv the National Natural Science Foundation of China(Grant No.50975164)the Science and Technology Planning Project of Shandong Proyince(Grant No.J09LD05)the Foundation of Key LaboratOry of Mine Hazard Prevention and Control (Grant No.MDPC0810)
文摘With the increase in mining depth, mine heat harm has appeared to be more prominent. The mine heat harm could be resolvedor reduced by ice refrigeration. Thus, ice transportation through pipeline becomes a critical problem; typically flowresistance occurs in the elbow. In the present study, according to the analysis of the surface morphology of fish scale, abiomimetic functional surface structure for the interior wall of elbow is designed. Based on the theory of liquid-solid two phaseflow, a CFD numerical simulation of ice-water mixture flowing through the elbow is carried out using finite element method.Conventional experiments of pressure drop and flow resistance for both bionic and common elbows are conducted to test theeffect of the bionic elbow on flow resistance reduction. It is found that with the increase in the ice mass fraction in the ice-watermixture, the effect of bionic elbow on resistance reduction becomes more obvious.
基金the Dyn Fluid Laboratory at Arts et Métiers Paris Tech
文摘This paper presents an experimental study of the physical characteristic effects of large particles on hydraulic transport in a horizontal pipe.The particles are spherical and are large with respect to the diameter of the pipe(8%,10%,16% and 25%).Experiments were done to test the important parameters in solid transport(pressure,velocity,etc.).As a result,the relationship between the pressure gradient forces and the mixture velocity was substantially different from the pure liquid flow.However,in a single-phase flow a monotonous behavior of the pressure drop curve is observed,and the curve of the solid particle flow attains its minimum at the critical velocity.The regimes are characterized with differential pressure measurements and visualizations.
基金financially supported by the National Natural Science Foundation of China(No.19934003)the Natural Science Foundation of the Education Bureau of Anhui Province,China(Nos.KJ2011A259 and KJ2012Z404)+1 种基金Anhui Key Laboratory of Spintronics and Nano-materials Program(Nos.2010YKF01 and 2010YKF04)the Professors’and Doctors’ Research Startup Foundation of Suzhou University(Nos.2011jb01 and 2010jb02)
文摘The samples of La8/9Sr1/45Na4/45MnO3(LSNMO)/x2(Sb2O3) were prepared by the solid-state reaction method. The electric transport properties and the temperature stability of magnetoresistance(MR) of the samples were studied through the measurements of X-ray diffraction patterns, resistivity–temperature(q–T) curves, mass magnetization– temperature(r–T) curves, and magnetoresistance–temperature(MR–T) curves. The results indicate that the q–T curves of the original material LSNMO show two peaks, and the phenomenon of two peaks of q–T curves disappears for the composite samples, which can be explained by a competition between surface-phase resistivity induced by boundarydependent scattering and body-phase resistivity induced by paramagnetism–ferromagnetism transition. For all the samples in the low temperature range, MR increases continuously with the decrease of temperature, which shows a characteristic of low-field magnetoresistance. However, MR basically keeps the same in the high temperature range. The paramagnetism–ferromagnetism transition is observed in the high temperature range due to a composite between perovskite manganite and insulator, which can enhance the temperature of MR appearance in the high temperature range and make it to appear near room temperature. For the sample with x = 0.12, MR remains constant at the value of 7.5 % in the temperature range of 300–260 K, which achieves a temperature stability of MR near room temperature. In addition,for the sample with x = 0.16, MR is above 6.8 % in the high temperature range of 318–252 K(DT = 66 K). MR almost remains constant in this temperature range, which favors the practical application of MR.
基金National Natural Science Foundation of China，the Foundation of Harbin Institute of Technology
文摘The transport properties of gluon in color space in a system of coexistence of both hadronic and QGP phases are investigated from the quantum transport equation of gluon.
