Dielectrophoresis （DEP） is one of the most popular techniques for bio-particle manipulation in microfluidic systems. Traditional calculation of dielectrophoretic forces of single particle based on the approximation ...Dielectrophoresis （DEP） is one of the most popular techniques for bio-particle manipulation in microfluidic systems. Traditional calculation of dielectrophoretic forces of single particle based on the approximation of equivalent dipole moment （EDM） cannot be directly applied on the dense particle interactions in an electrical field. The Maxwell stress tensor （MST） method is strictly accurate in the theory for dielectrophoretic forces of particle interaction, but the cumbersome and complicated numerical computation greatly limits its practical applications. A novel iterative dipole moment （IDM） method is pre- sented in this work for calculating the dielectrophoretic forces of particle-particle inter- actions. The accuracy, convergence, and simplicity of the IDM are confirmed by a series of examples of two-particle interaction in a DC/AC electrical field. The results indicate that the IDM is able to calculate the DEP particle interaction forces in good agreement with the MST method. The IDM is a purely analytical operation and does not require complicated numerical computation for solving the differential equations of an electrical field while the particle is moving.展开更多
The thermoelectric and the thermospin transport properties, including electrical conductivity, Seebeck coefficient, thermal conductivity, and thermoelectric figure of merit, of a parallel coupled double-quantum-dot Ah...The thermoelectric and the thermospin transport properties, including electrical conductivity, Seebeck coefficient, thermal conductivity, and thermoelectric figure of merit, of a parallel coupled double-quantum-dot Aharonov-Bohm interferometer are investigated by means of the Green function technique. The periodic Anderson model is used to describe the quantum dot system, the Rashba spin-orbit interaction and the Zeeman splitting under a magnetic field are considered. The theoretical results show the constructive contribution of the Rashba effect and the influence of the magnetic field on the thermospin effects. We also show theoretically that material with a high figure of merit can be obtained by tuning the Zeeman splitting energy only.展开更多
Polycrystalline diamond compact(PDC)bit is one of the most widely used drill bits for improving the rate of penetration in deep oil and gas well and geothermal well.However,the dynamic rock fragmentation mechanics cha...Polycrystalline diamond compact(PDC)bit is one of the most widely used drill bits for improving the rate of penetration in deep oil and gas well and geothermal well.However,the dynamic rock fragmentation mechanics characteristics of PDC bits are still unclearly.A coupled fragmentation mechanics model of PDC cutter-rock interaction is established by combining the mixed fragmentation modes with dynamic strength.The coupling influence laws of cutter angle,cutting depth,dynamic strength ratio,breaking modes on the horizontal force coefficient(HFC),vertical force coefficient(VFC)and specific energy are analyzed.The model of this paper can optimize cutter inclination angle,cutting depth and minimum specific energy.With the increase of the cutter inclination angle,the dynamic VFC changes into two modes.The definition of the dynamic modes depends on the dynamic strength ratio.As the cutting angle increases,the cutting force increases.The cutting force increases nonlinearly with increasing cutting depth.The specific energy of rock fragmentation increases nonlinearly with increasing cutting depth.With the increase of dynamic strength,the specific energy of rock fragmentation increases nonlinearly.When the input-energy increases,the rate of penetration response is divided into three stages.The results have important guiding significance for the PDC bit design and drilling parameters optimization to increase the rate of penetration and the efficiency of exploration and development.展开更多
Gao＇s viscous/in-viscid interacting shear flows （ISF） theory, proposed by professor Gao Zhi in Institute of Mechanics, China Academy of Science, and its inferences and their applications in computational fluid dyna...Gao＇s viscous/in-viscid interacting shear flows （ISF） theory, proposed by professor Gao Zhi in Institute of Mechanics, China Academy of Science, and its inferences and their applications in computational fluid dynamics （CFD） are reviewed and some subjects worthy to be studied are pro- posed in this paper. The flow-field and motion law of ISF, mathematics definition of strong viscous shear layer flow in ISF, ISF equations, wall-surface compatibility criteria （Gao＇s criteria ）, space scale variety law of strong viscous shear layer reveals flow mechanism and local space small scale triggered by strong interaction that cause some abnormal severe local pneumatic heating phenomenon in hypersonic flow. Gao＇s ISF theory was used in near wall flow, free ISF flow simulation and design of computing grids, Gao＇s wall-surface criteria were used to verify calculation reliability and accuracy of near wall flows, ISF theory approximate analytical result of shock waves-boundary layer interac- tion and ISF equations were used to obtain the numerical exact solution of local area flow （ such as stationary point flow）. Some new subjects, such as, improving near-wall turbulent models according to the turbulent flow simulation satisfying the wall-criteria and illustrating relation between grid-con- vergence based on the wall criteria and other convergence tactics, are suggested. The necessity of applying Gao＇s ISF theory and wall criteria is revealed. Difficulties and importance of hypersonic vis- cous/in-viscid interaction phenomenon were also emphasized.展开更多
基金Project supported by the National Natural Science Foundation of China(No.11172111)
文摘Dielectrophoresis （DEP） is one of the most popular techniques for bio-particle manipulation in microfluidic systems. Traditional calculation of dielectrophoretic forces of single particle based on the approximation of equivalent dipole moment （EDM） cannot be directly applied on the dense particle interactions in an electrical field. The Maxwell stress tensor （MST） method is strictly accurate in the theory for dielectrophoretic forces of particle interaction, but the cumbersome and complicated numerical computation greatly limits its practical applications. A novel iterative dipole moment （IDM） method is pre- sented in this work for calculating the dielectrophoretic forces of particle-particle inter- actions. The accuracy, convergence, and simplicity of the IDM are confirmed by a series of examples of two-particle interaction in a DC/AC electrical field. The results indicate that the IDM is able to calculate the DEP particle interaction forces in good agreement with the MST method. The IDM is a purely analytical operation and does not require complicated numerical computation for solving the differential equations of an electrical field while the particle is moving.
基金Project supported by the Natural Science Foundation of Heilongjiang Province,China (Grant No. F200939)
文摘The thermoelectric and the thermospin transport properties, including electrical conductivity, Seebeck coefficient, thermal conductivity, and thermoelectric figure of merit, of a parallel coupled double-quantum-dot Aharonov-Bohm interferometer are investigated by means of the Green function technique. The periodic Anderson model is used to describe the quantum dot system, the Rashba spin-orbit interaction and the Zeeman splitting under a magnetic field are considered. The theoretical results show the constructive contribution of the Rashba effect and the influence of the magnetic field on the thermospin effects. We also show theoretically that material with a high figure of merit can be obtained by tuning the Zeeman splitting energy only.
基金work is supported by the project funded by China Post-doctoral Science Foundation(2020M683357)Sichuan Science and Technology Program(2022NSFSC0975)+1 种基金CNPC-SWPU innovation alliance(2020CX040202)Open Fund(PLN2021-19)of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Southwest Petroleum University).
文摘Polycrystalline diamond compact(PDC)bit is one of the most widely used drill bits for improving the rate of penetration in deep oil and gas well and geothermal well.However,the dynamic rock fragmentation mechanics characteristics of PDC bits are still unclearly.A coupled fragmentation mechanics model of PDC cutter-rock interaction is established by combining the mixed fragmentation modes with dynamic strength.The coupling influence laws of cutter angle,cutting depth,dynamic strength ratio,breaking modes on the horizontal force coefficient(HFC),vertical force coefficient(VFC)and specific energy are analyzed.The model of this paper can optimize cutter inclination angle,cutting depth and minimum specific energy.With the increase of the cutter inclination angle,the dynamic VFC changes into two modes.The definition of the dynamic modes depends on the dynamic strength ratio.As the cutting angle increases,the cutting force increases.The cutting force increases nonlinearly with increasing cutting depth.The specific energy of rock fragmentation increases nonlinearly with increasing cutting depth.With the increase of dynamic strength,the specific energy of rock fragmentation increases nonlinearly.When the input-energy increases,the rate of penetration response is divided into three stages.The results have important guiding significance for the PDC bit design and drilling parameters optimization to increase the rate of penetration and the efficiency of exploration and development.
基金Supported by the National Natural Science Foundation(10702009)
文摘Gao＇s viscous/in-viscid interacting shear flows （ISF） theory, proposed by professor Gao Zhi in Institute of Mechanics, China Academy of Science, and its inferences and their applications in computational fluid dynamics （CFD） are reviewed and some subjects worthy to be studied are pro- posed in this paper. The flow-field and motion law of ISF, mathematics definition of strong viscous shear layer flow in ISF, ISF equations, wall-surface compatibility criteria （Gao＇s criteria ）, space scale variety law of strong viscous shear layer reveals flow mechanism and local space small scale triggered by strong interaction that cause some abnormal severe local pneumatic heating phenomenon in hypersonic flow. Gao＇s ISF theory was used in near wall flow, free ISF flow simulation and design of computing grids, Gao＇s wall-surface criteria were used to verify calculation reliability and accuracy of near wall flows, ISF theory approximate analytical result of shock waves-boundary layer interac- tion and ISF equations were used to obtain the numerical exact solution of local area flow （ such as stationary point flow）. Some new subjects, such as, improving near-wall turbulent models according to the turbulent flow simulation satisfying the wall-criteria and illustrating relation between grid-con- vergence based on the wall criteria and other convergence tactics, are suggested. The necessity of applying Gao＇s ISF theory and wall criteria is revealed. Difficulties and importance of hypersonic vis- cous/in-viscid interaction phenomenon were also emphasized.
