The design of thermal conductivity enhancers(TCE) is quite critical to overcoming the disadvantage of the poor thermal conductivity of phase change materials(PCM).The main contribution of this study is firstly to disc...The design of thermal conductivity enhancers(TCE) is quite critical to overcoming the disadvantage of the poor thermal conductivity of phase change materials(PCM).The main contribution of this study is firstly to discuss how to actively enhance natural convection of the melted PCM in cellular structure by the fin formed in the structure under the condition of the same metal mass,apart from simultaneously improving heat conduction,which can boost the heat transfer performance.Also,a tailored hybrid fin-lattice structure(HFS) as TCE is designed and fabricated by additive manufacturing(AM).A two-equation numerical method is applied to study the heat transfer of the PCM,and its feasibility is validated with the experimental data.The numerical results indicate that enhanced natural convection and improved heat conduction can be obtained simultaneously when a well-designed fin is embedded into a lattice structure.The enhanced natural convection results in the improved melting rate and the decreased wall temperature;e.g.,the complete melting time and the wall temperature are reduced by 11.6% and 19.7%,respectively,because of the fin for metal aluminum.Moreover,the parameters of HFS including the porosity,pore density,and fin dimension have a great impact on the heat transfer.The enhancement effect of the fin for HFS on the melting rate of the PCM increases as the thermal conductivity of the base material decreases.For example,when the fin is introduced into the lattice structure,the complete melting time is reduced by 24.1% for metal titanium.In summary,this study enables us to obtain a good understanding of the mechanism of the heat transfer and provides necessary experimental data for the structural design of HFS fabricated by AM.展开更多
The crystal structure,mechanical stability,phonon dispersion,electronic transport properties and thermoelectric(TE)performance of the Bi_(2)Sn_(2)Te_(6)monolayer are assessed with the first-principles calculations and...The crystal structure,mechanical stability,phonon dispersion,electronic transport properties and thermoelectric(TE)performance of the Bi_(2)Sn_(2)Te_(6)monolayer are assessed with the first-principles calculations and the Boltzmann transport theory.The Bi_(2)Sn_(2)Te_(6)monolayer is an indirect semiconductor with a band gap of 0.91 eV using the Heyd-Scuseria-Ernzerhof(HSE06)functional in consideration of the spin-orbit coupling(SOC)effect.The Bi_(2)Sn_(2)Te_(6)monolayer is high thermodynamically and mechanically stable by the assessments of elastic modulus,phonon dispersion curves,and ab initio molecular dynamics(AIMD)simulations.The hybrid bonding characteristics are discovered in Bi_(2)Sn_(2)Te_(6)monolayer,which is advantageous for phonon scattering.The antibonding interactions near the Fermi level weaken the chemical bonding and reduce the phonon vibrational frequency.Due to the short phonon relaxation time,strong anharmonic scattering,large Grüneisen parameter,and small phonon group velocity,an ultralow lattice thermal conductivity(0.27 W/(m·K)@300 K)is achieved for the Bi_(2)Sn_(2)Te_(6)monolayer.The optimal dimensionless figure of merit(ZT)values for the n-type and p-type Bi_(2)Sn_(2)Te_(6)monolayers are 2.68 and 1.63 at 700 K,respectively,associated with a high TE conversion efficiency of 20.01%at the same temperature.Therefore,the Bi_(2)Sn_(2)Te_(6)monolayer emerges as a promising candidate for TE material with high conversion efficiency.展开更多
In this paper,three-dimensional(3D)novel hybrid lattice structures with exceptional mechanical properties and energy absorbing performances were proposed,and experimental and finite element simulation comparisons were...In this paper,three-dimensional(3D)novel hybrid lattice structures with exceptional mechanical properties and energy absorbing performances were proposed,and experimental and finite element simulation comparisons were performed to demonstrate their potential in mechanical application.First,different types of basic cubic unit cells were designed for constructing three types of novel hybrid metamaterials,in which stepped circulation of different unit cells was conceived to generate architected metamaterials.Afterwards,quasi-static compression experiments and finite element simulations were performed to study the deformation process and failure mechanisms of as-fabricated hybrid metamaterials.The energy absorption efficiency,specific energy absorption(SEA)indicators,and energy absorption capabilities of different hybrid lattice metamaterials were compared and analyzed.The results show that the deformation mechanisms of novel hybrid lattice were beneficial for generating remarkable elevated densification strain,and the energy absorption efficiency can be tailored by altering the types or sizes of basic unit cells.Strain-hardening and bilinear features were also obtained.展开更多
The Hefei Advanced Light Facility(HALF)proposed by the National Synchrotron Radiation Laboratory is a green-field vacuum ultraviolet and soft X-ray diffraction-limited storage ring light source with a beam energy of 2...The Hefei Advanced Light Facility(HALF)proposed by the National Synchrotron Radiation Laboratory is a green-field vacuum ultraviolet and soft X-ray diffraction-limited storage ring light source with a beam energy of 2.2 GeV and emittance goal of less than 100 pm rad.Inspired by the ESRF-EBS hybrid multi-bend achromat(HMBA),SLS-2,and Diamond-II lattices,we have proposed and designed a modified H6BA lattice as the baseline lattice of the HALF storage ring with 20 identical cells and a natural emittance of approximately 86 pm rad.In this paper,three other types of HMBA lattices including two H7BA lattices and a H6BA lattice are designed for HALF with the same number of cells.The main storage ring proper-ties of these four HMBA lattices are compared.Because the intra-beam scattering(IBS)effect is significant in the HALF storage ring,we calculate and compare the equilibrium emittances of the four lattices with IBS included.These comparisons show that the present modified H6BA lattice,which has a relatively low equilibrium emittance and more straight sections,is preferred for the HALF storage ring after a comprehensive consideration.展开更多
In this paper,a hybrid lattice Boltzmann flux solver(LBFS)is proposed for simulation of viscous compressible flows.In the solver,the finite volume method is applied to solve the Navier-Stokes equations.Different from ...In this paper,a hybrid lattice Boltzmann flux solver(LBFS)is proposed for simulation of viscous compressible flows.In the solver,the finite volume method is applied to solve the Navier-Stokes equations.Different from conventional Navier-Stokes solvers,in this work,the inviscid flux across the cell interface is evaluated by local reconstruction of solution using one-dimensional lattice Boltzmann model,while the viscous flux is still approximated by conventional smooth function approximation.The present work overcomes the two major drawbacks of existing LBFS[28–31],which is used for simulation of inviscid flows.The first one is its ability to simulate viscous flows by including evaluation of viscous flux.The second one is its ability to effectively capture both strong shock waves and thin boundary layers through introduction of a switch function for evaluation of inviscid flux,which takes a value close to zero in the boundary layer and one around the strong shock wave.Numerical experiments demonstrate that the present solver can accurately and effectively simulate hypersonic viscous flows.展开更多
In recent years,a new generation of storage ring-based light sources,known as diffraction-limited storage rings(DLSRs),whose emittance approaches the diffraction limit for the range of X-ray wavelengths of interest to...In recent years,a new generation of storage ring-based light sources,known as diffraction-limited storage rings(DLSRs),whose emittance approaches the diffraction limit for the range of X-ray wavelengths of interest to the scientific community,has garnered significant attention worldwide.Researchers have begun to design and build DLSRs.Among various DLSR proposals,the hybrid multibend achromat(H-MBA)lattice enables sextupole strengths to be maintained at a reasonable level when minimizing the emittance;hence,it has been adopted in many DLSR designs.Based on the H-7BA lattice,the design of the Advanced Photon Source Upgrade Project(APS-U)can effectively reduce emittance by replacing six quadrupoles with anti-bends.Herein,we discuss the feasibility of designing an APS-U-type H-MBA lattice for the Southern Advanced Photon Source,a mid-energy DLSR light source with ultralow emittance that has been proposed to be built adjacent to the China Spallation Neutron Source.Both linear and nonlinear dynamics are optimized to obtain a detailed design of this type of lattice.The emittance is minimized,while a sufficiently large dynamic aperture(DA)and momentum acceptance(MA)are maintained.A design comprising 36 APS-U type H-7BAs,with an energy of 3 GeV and a circumference of 972 m,is achieved.The horizontal natural emittance is 20 pm·rad,with a horizontal DA of 5.8 mm,a vertical DA of 4.5 mm,and an MA of 4%,as well as a long longitudinal damping time of 120 ms.Subsequently,a few modifications are performed based on the APS-U-type lattice to reduce the maximum value of damping time from 120 to 44 ms while maintaining other performance parameters at the same level.展开更多
In this paper,the finite difference weighted essentially non-oscillatory (WENO) scheme is incorporated into the recently developed four kinds of lattice Boltzmann flux solver (LBFS) to simulate compressible flows,incl...In this paper,the finite difference weighted essentially non-oscillatory (WENO) scheme is incorporated into the recently developed four kinds of lattice Boltzmann flux solver (LBFS) to simulate compressible flows,including inviscid LBFS Ⅰ,viscous LBFS Ⅱ,hybrid LBFS Ⅲ and hybrid LBFS Ⅳ.Hybrid LBFS can automatically realize the switch between inviscid LBFS Ⅰ and viscous LBFS Ⅱ through introducing a switch function.The resultant hybrid WENO-LBFS scheme absorbs the advantages of WENO scheme and hybrid LBFS.We investigate the performance of WENO scheme based on four kinds of LBFS systematically.Numerical results indicate that the devopled hybrid WENO-LBFS scheme has high accuracy,high resolution and no oscillations.It can not only accurately calculate smooth solutions,but also can effectively capture contact discontinuities and strong shock waves.展开更多
We first construct the effective chiral Lagrangians tor the 1^-＋ exotic mesons.With the infrared regularization scheme,we derive the one-loop infrared singular chiral corrections to the π1（1600） mass explicitly.We...We first construct the effective chiral Lagrangians tor the 1^-＋ exotic mesons.With the infrared regularization scheme,we derive the one-loop infrared singular chiral corrections to the π1（1600） mass explicitly.We investigate the variation of the different chiral corrections with the pion mass under two schemes.Hopefully,the explicit non-analytical chiral structures will be helpful for the chiral extrapolation of lattice data from the dynamical lattice QCD simulation of either the exotic light hybrid meson or the tetraquark state.展开更多
A discontinuous Galerkin(DG)-based lattice Boltzmann method is employed to solve the Euler and Navier-Stokes equations.Instead of adopting the widely used local Lax-Friedrichs flux and Roe Flux etc.,a hybrid lattice B...A discontinuous Galerkin(DG)-based lattice Boltzmann method is employed to solve the Euler and Navier-Stokes equations.Instead of adopting the widely used local Lax-Friedrichs flux and Roe Flux etc.,a hybrid lattice Boltzmann flux solver(LBFS)is employed to evaluate the inviscid flux across the cell interfaces.The main advantage of the hybrid LBFS is its flexibility for capturing both strong shocks and thin boundary layers through introducing a function which varies from zero to one to control the artificial viscosity.Numerical results indicate that the hybrid lattice Boltzmann flux solver behaves very well combining with the high-order DG method when simulating both inviscid and viscous flows.展开更多
Based on the homogenous balance method and the trial function method, several trial function methods composed of exponential functions are proposed and applied to nonlinear discrete systems. With the.help of symbolic ...Based on the homogenous balance method and the trial function method, several trial function methods composed of exponential functions are proposed and applied to nonlinear discrete systems. With the.help of symbolic computation system, the new exact solitary wave solutions to discrete nonlinear mKdV lattice equation, discrete nonlinear （2 ＋ 1） dimensional Toda lattice equation, Ablowitz-Ladik-lattice system are constructed.The method is of significance to seek exact solitary wave solutions to other nonlinear discrete systems.展开更多
In this paper,a hybrid Lattice Boltzmann Flux Solver(LBFS)with an improved switch function is proposed for simulation of integrated hypersonic fluid-thermal-structural problems.In the solver,the macroscopic Navier–St...In this paper,a hybrid Lattice Boltzmann Flux Solver(LBFS)with an improved switch function is proposed for simulation of integrated hypersonic fluid-thermal-structural problems.In the solver,the macroscopic Navier–Stokes equations and structural heat transfer equation are discretized by the finite volume method,and the numerical fluxes at the cell interface are reconstructed by the local solution of the Boltzmann equation.To compute the numerical fluxes,two equilibrium distribution functions are introduced.One is the D1Q4 discrete velocity model for calculating the inviscid flux across the cell interface of Navier–Stokes equations,and the other is the D2Q4 model for evaluating the flux of structural energy equation.In this work,a new dual thermal resistance model is proposed to calculate the thermal properties at the fluid–solid interface.The accuracy and stability of the present hybrid solver are validated by simulating several numerical examples,including the fluid-thermal-structural problem of cylindrical leading edge.Numerical results show that the present solver can accurately predict the thermal properties of hypersonic fluid-thermalstructural problems and has the great potential for solving fluid-thermal-structural problems of long-endurance high-speed vehicles.展开更多
The hybrid lattice, known as a discrete Korteweg-de Vries (KdV) equation, is found to be a discrete modified Korteweg-de Vries (mKdV) equation in this paper. The coupled hybrid lattice, which is pointed to be a discre...The hybrid lattice, known as a discrete Korteweg-de Vries (KdV) equation, is found to be a discrete modified Korteweg-de Vries (mKdV) equation in this paper. The coupled hybrid lattice, which is pointed to be a discrete coupled KdV system, is also found to be discrete form of a coupled mKdV systems. Delayed differential reduction system and pure difference systems are derived from the coupled hybrid system by means of the symmetry reduction approach. Cnoidal wave, positon and negaton solutions for the coupled hybrid system are proposed.展开更多
In this paper, we have successfully extended the Jacobian elliptic function expansion approach to nonlinear differential-difference equations. The Hybrid lattice equation is chosen to illustrate this approach. As a co...In this paper, we have successfully extended the Jacobian elliptic function expansion approach to nonlinear differential-difference equations. The Hybrid lattice equation is chosen to illustrate this approach. As a consequence, twelve families of Jacobian elliptic function solutions with different parameters of the Hybrid lattice equation are obtained. When the modulus m → 1 or O, doubly-periodic solutions degenerate to solitonic solutions and trigonometric function solutions, respectively.展开更多
In the present study, pool boiling heat transfer performance and bubble behaviors of hybrid structures with metal foam and square column are investigated by lattice Boltzmann method. By using the vapor-liquid phase ch...In the present study, pool boiling heat transfer performance and bubble behaviors of hybrid structures with metal foam and square column are investigated by lattice Boltzmann method. By using the vapor-liquid phase change model of Gong-Cheng and Peng-Robinson equation of state, the effects of structural parameters, including metal foam thickness, porosity, column height and ratio of column width(W) to gap spacing(D) are investigated in details. The results show that hybrid structure performs better than pure columnar structure in pool boiling heat transfer. The hybrid structure accelerates bubble growth by fluid disturbance while metal skeletons prevent the bubble escaping. The optimum ratio of column width to gap spacing decreases with the increase of heat flux and HTC(heat transfer coefficient) can achieve an increase up to 25% when W/D change from 5/3 to 1/3. The increase of column height enhances heat transfer by expanding surface area and providing space for bubble motion. The metal foam thickness and porosity have a little influence on pool boiling heat transfer performance, but they have an important effect on bubble motion in the regime.展开更多
This paper presents a hybrid lattice Boltzmann solver for turbulent buoyancy-driven flow coupled with surface thermal radiation.The two-relaxation time scheme for the Boltzmann equation combined with the implicit fini...This paper presents a hybrid lattice Boltzmann solver for turbulent buoyancy-driven flow coupled with surface thermal radiation.The two-relaxation time scheme for the Boltzmann equation combined with the implicit finite difference scheme for the energy equation is implemented to compute the heat transfer and fluid flow characteristics.The accuracy and robustness of the hybrid approach proposed in this study are assessed in terms of the numerical and experimental data of other researchers.Upon performing the simulation,the Rayleigh number is ranged from 108 to 1010 whereas the surface emissivity is changed from zero to unity.During computations,it is found that the overall temperature of the cavity is increased as a result of enhancing the surface radiation.Convective plumes are formed both at the isothermal and the thermally-insulated walls with the Ra109 and#0.6.In the conditions under study,the overall heat transfer rate is raised by around 5%when taking into account the surface thermal radiation.展开更多
Hybrid lattice structures consisting of multiple microstructures have drawn much attention due to their excellent performance and extraordinary designability.This work puts forward a novel design scheme of lightweight...Hybrid lattice structures consisting of multiple microstructures have drawn much attention due to their excellent performance and extraordinary designability.This work puts forward a novel design scheme of lightweight hybrid lattice structures based on independent continuous mapping(ICM)method.First,the effective elastic properties of various microstructure configurations serve as a bridge between the macrostructure and the multiple microstructures by the homogenization theory.Second,a concurrent topology optimization model for seeking optimized macroscale topology and the specified microstructures is established and solved by a generalized multi-material interpolation formulation and sensitivity analysis.Third,several numerical examples show that hybrid lattice structures with different anisotropic configurations accomplish a better lightweight effect than those with various orthogonal configurations,which verifies the feasibility of the presented method.Hence,anisotropic configurations are more conducive to the sufficient utilization of constitutive material.The proposed scheme supplies a reference for the design of hybrid lattice structures and extends the application field of the ICM method.展开更多
基金the National Natural Science Foundation of China (Grant No.11972105,U1808215 and 11821202)the 111 Project (B14013)the Fundamental Research Funds for the Central Universities of China。
文摘The design of thermal conductivity enhancers(TCE) is quite critical to overcoming the disadvantage of the poor thermal conductivity of phase change materials(PCM).The main contribution of this study is firstly to discuss how to actively enhance natural convection of the melted PCM in cellular structure by the fin formed in the structure under the condition of the same metal mass,apart from simultaneously improving heat conduction,which can boost the heat transfer performance.Also,a tailored hybrid fin-lattice structure(HFS) as TCE is designed and fabricated by additive manufacturing(AM).A two-equation numerical method is applied to study the heat transfer of the PCM,and its feasibility is validated with the experimental data.The numerical results indicate that enhanced natural convection and improved heat conduction can be obtained simultaneously when a well-designed fin is embedded into a lattice structure.The enhanced natural convection results in the improved melting rate and the decreased wall temperature;e.g.,the complete melting time and the wall temperature are reduced by 11.6% and 19.7%,respectively,because of the fin for metal aluminum.Moreover,the parameters of HFS including the porosity,pore density,and fin dimension have a great impact on the heat transfer.The enhancement effect of the fin for HFS on the melting rate of the PCM increases as the thermal conductivity of the base material decreases.For example,when the fin is introduced into the lattice structure,the complete melting time is reduced by 24.1% for metal titanium.In summary,this study enables us to obtain a good understanding of the mechanism of the heat transfer and provides necessary experimental data for the structural design of HFS fabricated by AM.
基金supported by the National Natural Science Foundation of China(Grant No.21503039)Department of Science and Technology of Liaoning Province(Grant No.2019MS164)+1 种基金Department of Education of Liaoning Province(Grant Nos.LJ2020JCL034,JYTQN2023209)Discipline Innovation Team of Liaoning Technical University(Grant No.LNTU20TD-16)。
文摘The crystal structure,mechanical stability,phonon dispersion,electronic transport properties and thermoelectric(TE)performance of the Bi_(2)Sn_(2)Te_(6)monolayer are assessed with the first-principles calculations and the Boltzmann transport theory.The Bi_(2)Sn_(2)Te_(6)monolayer is an indirect semiconductor with a band gap of 0.91 eV using the Heyd-Scuseria-Ernzerhof(HSE06)functional in consideration of the spin-orbit coupling(SOC)effect.The Bi_(2)Sn_(2)Te_(6)monolayer is high thermodynamically and mechanically stable by the assessments of elastic modulus,phonon dispersion curves,and ab initio molecular dynamics(AIMD)simulations.The hybrid bonding characteristics are discovered in Bi_(2)Sn_(2)Te_(6)monolayer,which is advantageous for phonon scattering.The antibonding interactions near the Fermi level weaken the chemical bonding and reduce the phonon vibrational frequency.Due to the short phonon relaxation time,strong anharmonic scattering,large Grüneisen parameter,and small phonon group velocity,an ultralow lattice thermal conductivity(0.27 W/(m·K)@300 K)is achieved for the Bi_(2)Sn_(2)Te_(6)monolayer.The optimal dimensionless figure of merit(ZT)values for the n-type and p-type Bi_(2)Sn_(2)Te_(6)monolayers are 2.68 and 1.63 at 700 K,respectively,associated with a high TE conversion efficiency of 20.01%at the same temperature.Therefore,the Bi_(2)Sn_(2)Te_(6)monolayer emerges as a promising candidate for TE material with high conversion efficiency.
基金supported by the National Natural Science Foundation of China(Grant Nos.11702023,11972081,51305223).
文摘In this paper,three-dimensional(3D)novel hybrid lattice structures with exceptional mechanical properties and energy absorbing performances were proposed,and experimental and finite element simulation comparisons were performed to demonstrate their potential in mechanical application.First,different types of basic cubic unit cells were designed for constructing three types of novel hybrid metamaterials,in which stepped circulation of different unit cells was conceived to generate architected metamaterials.Afterwards,quasi-static compression experiments and finite element simulations were performed to study the deformation process and failure mechanisms of as-fabricated hybrid metamaterials.The energy absorption efficiency,specific energy absorption(SEA)indicators,and energy absorption capabilities of different hybrid lattice metamaterials were compared and analyzed.The results show that the deformation mechanisms of novel hybrid lattice were beneficial for generating remarkable elevated densification strain,and the energy absorption efficiency can be tailored by altering the types or sizes of basic unit cells.Strain-hardening and bilinear features were also obtained.
基金the Fundamental Research Funds for the Central Universities(No.WK2310000107)the National Key Research and Development Program of China(No.2016YFA0402000)National Natural Science Foundation of China(Nos.12205299,11875259,12105284).
文摘The Hefei Advanced Light Facility(HALF)proposed by the National Synchrotron Radiation Laboratory is a green-field vacuum ultraviolet and soft X-ray diffraction-limited storage ring light source with a beam energy of 2.2 GeV and emittance goal of less than 100 pm rad.Inspired by the ESRF-EBS hybrid multi-bend achromat(HMBA),SLS-2,and Diamond-II lattices,we have proposed and designed a modified H6BA lattice as the baseline lattice of the HALF storage ring with 20 identical cells and a natural emittance of approximately 86 pm rad.In this paper,three other types of HMBA lattices including two H7BA lattices and a H6BA lattice are designed for HALF with the same number of cells.The main storage ring proper-ties of these four HMBA lattices are compared.Because the intra-beam scattering(IBS)effect is significant in the HALF storage ring,we calculate and compare the equilibrium emittances of the four lattices with IBS included.These comparisons show that the present modified H6BA lattice,which has a relatively low equilibrium emittance and more straight sections,is preferred for the HALF storage ring after a comprehensive consideration.
基金supported by the State Key Laboratory of Aerodynamics of China(No.SKLA201401).
文摘In this paper,a hybrid lattice Boltzmann flux solver(LBFS)is proposed for simulation of viscous compressible flows.In the solver,the finite volume method is applied to solve the Navier-Stokes equations.Different from conventional Navier-Stokes solvers,in this work,the inviscid flux across the cell interface is evaluated by local reconstruction of solution using one-dimensional lattice Boltzmann model,while the viscous flux is still approximated by conventional smooth function approximation.The present work overcomes the two major drawbacks of existing LBFS[28–31],which is used for simulation of inviscid flows.The first one is its ability to simulate viscous flows by including evaluation of viscous flux.The second one is its ability to effectively capture both strong shock waves and thin boundary layers through introduction of a switch function for evaluation of inviscid flux,which takes a value close to zero in the boundary layer and one around the strong shock wave.Numerical experiments demonstrate that the present solver can accurately and effectively simulate hypersonic viscous flows.
基金Project supported by the Natural Science Foundation of China(10461006)the Natural Science Foundation of Inner Mongolia(2004080201103)the High Education Science Research Programof Inner Mongolia(NJ02035)
基金This work was supported by the National Natural Science Foundation of China(No.11922512)the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.Y201904)the Guangdong Basic and Applied Basic Research Foundation—Guangdong Dongguan Joint Foundation(No.2019B1515120069).
文摘In recent years,a new generation of storage ring-based light sources,known as diffraction-limited storage rings(DLSRs),whose emittance approaches the diffraction limit for the range of X-ray wavelengths of interest to the scientific community,has garnered significant attention worldwide.Researchers have begun to design and build DLSRs.Among various DLSR proposals,the hybrid multibend achromat(H-MBA)lattice enables sextupole strengths to be maintained at a reasonable level when minimizing the emittance;hence,it has been adopted in many DLSR designs.Based on the H-7BA lattice,the design of the Advanced Photon Source Upgrade Project(APS-U)can effectively reduce emittance by replacing six quadrupoles with anti-bends.Herein,we discuss the feasibility of designing an APS-U-type H-MBA lattice for the Southern Advanced Photon Source,a mid-energy DLSR light source with ultralow emittance that has been proposed to be built adjacent to the China Spallation Neutron Source.Both linear and nonlinear dynamics are optimized to obtain a detailed design of this type of lattice.The emittance is minimized,while a sufficiently large dynamic aperture(DA)and momentum acceptance(MA)are maintained.A design comprising 36 APS-U type H-7BAs,with an energy of 3 GeV and a circumference of 972 m,is achieved.The horizontal natural emittance is 20 pm·rad,with a horizontal DA of 5.8 mm,a vertical DA of 4.5 mm,and an MA of 4%,as well as a long longitudinal damping time of 120 ms.Subsequently,a few modifications are performed based on the APS-U-type lattice to reduce the maximum value of damping time from 120 to 44 ms while maintaining other performance parameters at the same level.
基金This study was supported by the National Natural Science Foundation of China(Grants 11372168,11772179).
文摘In this paper,the finite difference weighted essentially non-oscillatory (WENO) scheme is incorporated into the recently developed four kinds of lattice Boltzmann flux solver (LBFS) to simulate compressible flows,including inviscid LBFS Ⅰ,viscous LBFS Ⅱ,hybrid LBFS Ⅲ and hybrid LBFS Ⅳ.Hybrid LBFS can automatically realize the switch between inviscid LBFS Ⅰ and viscous LBFS Ⅱ through introducing a switch function.The resultant hybrid WENO-LBFS scheme absorbs the advantages of WENO scheme and hybrid LBFS.We investigate the performance of WENO scheme based on four kinds of LBFS systematically.Numerical results indicate that the devopled hybrid WENO-LBFS scheme has high accuracy,high resolution and no oscillations.It can not only accurately calculate smooth solutions,but also can effectively capture contact discontinuities and strong shock waves.
基金Supported by National Natural Science Foundation of China(11222547,11175073,11575008)and 973 Programsupported by the National Youth Top-Level Talent Support Program(“Thousand Talents Scheme”)
文摘We first construct the effective chiral Lagrangians tor the 1^-＋ exotic mesons.With the infrared regularization scheme,we derive the one-loop infrared singular chiral corrections to the π1（1600） mass explicitly.We investigate the variation of the different chiral corrections with the pion mass under two schemes.Hopefully,the explicit non-analytical chiral structures will be helpful for the chiral extrapolation of lattice data from the dynamical lattice QCD simulation of either the exotic light hybrid meson or the tetraquark state.
文摘A discontinuous Galerkin(DG)-based lattice Boltzmann method is employed to solve the Euler and Navier-Stokes equations.Instead of adopting the widely used local Lax-Friedrichs flux and Roe Flux etc.,a hybrid lattice Boltzmann flux solver(LBFS)is employed to evaluate the inviscid flux across the cell interfaces.The main advantage of the hybrid LBFS is its flexibility for capturing both strong shocks and thin boundary layers through introducing a function which varies from zero to one to control the artificial viscosity.Numerical results indicate that the hybrid lattice Boltzmann flux solver behaves very well combining with the high-order DG method when simulating both inviscid and viscous flows.
基金the National Natural Science Foundation of China (10461006)the Science Research Foundation of Institution of Higher Education of Inner Mongolia Autonomous Region (NJZZ07031)+1 种基金the Natural Science Foundation of Inner Mongolia Autonomous Region (200408020103)the Natural Science Research Program of Inner Mongolia Normal University (QN005023)
文摘Based on the homogenous balance method and the trial function method, several trial function methods composed of exponential functions are proposed and applied to nonlinear discrete systems. With the.help of symbolic computation system, the new exact solitary wave solutions to discrete nonlinear mKdV lattice equation, discrete nonlinear （2 ＋ 1） dimensional Toda lattice equation, Ablowitz-Ladik-lattice system are constructed.The method is of significance to seek exact solitary wave solutions to other nonlinear discrete systems.
基金co-supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province of China(No.KYCX17_0235)Nanjing University of Aeronautics and Astronautics Ph D Short-term Visiting Scholar Project(No.180602DF01)National Numerical Wind Tunnel Project(Nos.NNW2018-ZT3B08 and NNW2019-ZT7B30)。
文摘In this paper,a hybrid Lattice Boltzmann Flux Solver(LBFS)with an improved switch function is proposed for simulation of integrated hypersonic fluid-thermal-structural problems.In the solver,the macroscopic Navier–Stokes equations and structural heat transfer equation are discretized by the finite volume method,and the numerical fluxes at the cell interface are reconstructed by the local solution of the Boltzmann equation.To compute the numerical fluxes,two equilibrium distribution functions are introduced.One is the D1Q4 discrete velocity model for calculating the inviscid flux across the cell interface of Navier–Stokes equations,and the other is the D2Q4 model for evaluating the flux of structural energy equation.In this work,a new dual thermal resistance model is proposed to calculate the thermal properties at the fluid–solid interface.The accuracy and stability of the present hybrid solver are validated by simulating several numerical examples,including the fluid-thermal-structural problem of cylindrical leading edge.Numerical results show that the present solver can accurately predict the thermal properties of hypersonic fluid-thermalstructural problems and has the great potential for solving fluid-thermal-structural problems of long-endurance high-speed vehicles.
基金Supported by the Natural Science Foundation of Guangdong Province of China under Grant No. 10452840301004616the National Natural Science Foundation of China under Grant No. 61001018the Scientific Research Foundation for the Doctors of University of Electronic Science and Technology of China Zhongshan Institute under Grant No. 408YKQ09
文摘The hybrid lattice, known as a discrete Korteweg-de Vries (KdV) equation, is found to be a discrete modified Korteweg-de Vries (mKdV) equation in this paper. The coupled hybrid lattice, which is pointed to be a discrete coupled KdV system, is also found to be discrete form of a coupled mKdV systems. Delayed differential reduction system and pure difference systems are derived from the coupled hybrid system by means of the symmetry reduction approach. Cnoidal wave, positon and negaton solutions for the coupled hybrid system are proposed.
文摘In this paper, we have successfully extended the Jacobian elliptic function expansion approach to nonlinear differential-difference equations. The Hybrid lattice equation is chosen to illustrate this approach. As a consequence, twelve families of Jacobian elliptic function solutions with different parameters of the Hybrid lattice equation are obtained. When the modulus m → 1 or O, doubly-periodic solutions degenerate to solitonic solutions and trigonometric function solutions, respectively.
基金supported by the National Natural Science Foundation of China(Grant No.52276075)。
文摘In the present study, pool boiling heat transfer performance and bubble behaviors of hybrid structures with metal foam and square column are investigated by lattice Boltzmann method. By using the vapor-liquid phase change model of Gong-Cheng and Peng-Robinson equation of state, the effects of structural parameters, including metal foam thickness, porosity, column height and ratio of column width(W) to gap spacing(D) are investigated in details. The results show that hybrid structure performs better than pure columnar structure in pool boiling heat transfer. The hybrid structure accelerates bubble growth by fluid disturbance while metal skeletons prevent the bubble escaping. The optimum ratio of column width to gap spacing decreases with the increase of heat flux and HTC(heat transfer coefficient) can achieve an increase up to 25% when W/D change from 5/3 to 1/3. The increase of column height enhances heat transfer by expanding surface area and providing space for bubble motion. The metal foam thickness and porosity have a little influence on pool boiling heat transfer performance, but they have an important effect on bubble motion in the regime.
文摘This paper presents a hybrid lattice Boltzmann solver for turbulent buoyancy-driven flow coupled with surface thermal radiation.The two-relaxation time scheme for the Boltzmann equation combined with the implicit finite difference scheme for the energy equation is implemented to compute the heat transfer and fluid flow characteristics.The accuracy and robustness of the hybrid approach proposed in this study are assessed in terms of the numerical and experimental data of other researchers.Upon performing the simulation,the Rayleigh number is ranged from 108 to 1010 whereas the surface emissivity is changed from zero to unity.During computations,it is found that the overall temperature of the cavity is increased as a result of enhancing the surface radiation.Convective plumes are formed both at the isothermal and the thermally-insulated walls with the Ra109 and#0.6.In the conditions under study,the overall heat transfer rate is raised by around 5%when taking into account the surface thermal radiation.
基金This work was supported by the Beijing Natural Science Foundation(No.3192005)National Natural Science Foundation of China(No.11872080)Taishan University Youth Teacher Science Foundation(No.QN-01-201901).
文摘Hybrid lattice structures consisting of multiple microstructures have drawn much attention due to their excellent performance and extraordinary designability.This work puts forward a novel design scheme of lightweight hybrid lattice structures based on independent continuous mapping(ICM)method.First,the effective elastic properties of various microstructure configurations serve as a bridge between the macrostructure and the multiple microstructures by the homogenization theory.Second,a concurrent topology optimization model for seeking optimized macroscale topology and the specified microstructures is established and solved by a generalized multi-material interpolation formulation and sensitivity analysis.Third,several numerical examples show that hybrid lattice structures with different anisotropic configurations accomplish a better lightweight effect than those with various orthogonal configurations,which verifies the feasibility of the presented method.Hence,anisotropic configurations are more conducive to the sufficient utilization of constitutive material.The proposed scheme supplies a reference for the design of hybrid lattice structures and extends the application field of the ICM method.
