The empirical rules for the prediction of solid solution formation proposed so far in the literature usually have very compromised predictability.Some rules with seemingly good predictability were,however,tested using...The empirical rules for the prediction of solid solution formation proposed so far in the literature usually have very compromised predictability.Some rules with seemingly good predictability were,however,tested using small data sets.Based on an unprecedented large dataset containing 1252 multicomponent alloys,machine-learning methods showed that the formation of solid solutions can be very accurately predicted(93%).The machine-learning results help identify the most important features,such as molar volume,bulk modulus,and melting temperature.展开更多
In this research,a Graphical Processing Unit(GPU)accelerated Discrete Element Method(DEM)code was developed and coupled with the Computational Fluid Dynamic(CFD)software MFiX to simulate granular and multiphase flows ...In this research,a Graphical Processing Unit(GPU)accelerated Discrete Element Method(DEM)code was developed and coupled with the Computational Fluid Dynamic(CFD)software MFiX to simulate granular and multiphase flows with heat transfers and chemical reactions.The Fortran-based CFD solver was coupled with the CUDA/C++based DEM solver through inter-process pipes.The speedup to the CPU version of MFiX-DEM is about 130-243 folds in the simulation of particle packings.In fluidized bed simulations,the DEM computation time is reduced from 91%to 17%with a speedup of 78 folds.The simulation of Geldart A particle fluidization revealed a similar level of importance of both fluid and particle coarse-graining.The filtered drag derived from the two-fluid model is suitable for Euler-Lagrangian simulations with both fluid and particle coarse-graining.It overcorrects the influence of sub-grid structures if used for simulations with only fluid coarse-graining.展开更多
Polysiloxane coatings on yttria stabilized zirconia(YSZ)microspheres of 500μm were simulated in a spout fluidized bed coater using Multiphase Flow with Interface Exchange-Discrete Element Modelling(MFiX-DEM).Two diff...Polysiloxane coatings on yttria stabilized zirconia(YSZ)microspheres of 500μm were simulated in a spout fluidized bed coater using Multiphase Flow with Interface Exchange-Discrete Element Modelling(MFiX-DEM).Two different coater configurations were developed to study the influence of gas velocity and its distribution on particle dynamics.The presence of the Wurster tube not only enhances the dis-tribution but also increases the overall residence time of the particles.Investigations were also carried out with different Wurster tube positions(normal,10%and 20%lowered from its initial position).Among these,20%lowered Wurster tube position demonstrated the most effective coating process.The effects of gas inlet pressure on the average gas velocity and the distribution of particles were analyzed.More than 97%of the particles can be retained.The derived results,including average gas velocity,particle retention percentage,and distribution of particles with gas velocity,are being used to guide the experimental work in obtaining defect-free coatings for YSZ microspheres.展开更多
This article presents the development and validation of the Superquadric Discrete Element Method(SuperDEM)for non-spherical particle simulation using a superquadric particle method in open-source CFD suite MFiX.A supe...This article presents the development and validation of the Superquadric Discrete Element Method(SuperDEM)for non-spherical particle simulation using a superquadric particle method in open-source CFD suite MFiX.A superquadric particle-particle contact algorithm with accelerating and stabilizing strategy was developed.A superquadric particle-arbitrary wall contact algorithm was developed,which enables the simulation in complex geometry.The solver was validated by comparing with experimental data generated in this study or available in the literature.Tests include cylinder contacting with a wall,static packing of M&M chocolate candies in a cylindrical container,static packing of cylinders in a cylindrical container,dynamic angle of repose of cylinders in a rotating drum,and discharging of chocolate candies from a hopper.Besides,MPI parallelization of the solver was implemented and the parallel performance of the solver using MPI was assessed through large-scale simulations of 1 million,10 million,and 100 million particles on up to 6800 cores,which demonstrates that the SuperDEM solver has great potential for industrial-scale systems simulation.展开更多
An unknown in coupled Eulerian-Lagrangian models for particle flow,such as CFD-DEM,which has received fairly little attention in the literature to date is the size of the filter width in the transfer kernel.This work ...An unknown in coupled Eulerian-Lagrangian models for particle flow,such as CFD-DEM,which has received fairly little attention in the literature to date is the size of the filter width in the transfer kernel.This work provides a preliminary glimpse at how this parameter can influence the solution in cold-flow,unbounded fluidization.Comparison to previously published direct numerical simulation data is used to suggest an appropriate range for this parameter.展开更多
A phase-field model is proposed to simulate coherency loss coupled with microstructure evolution.A special field variable is employed to describe the degree of coherency loss of each particle and its evolution is gove...A phase-field model is proposed to simulate coherency loss coupled with microstructure evolution.A special field variable is employed to describe the degree of coherency loss of each particle and its evolution is governed by a Ginzburg-Landau type kinetic equation.For the sake of computational efficiency,a flood-fill algorithm is introduced that can drastically reduce the required number of field variables,which allows the model to efficiently simulate a large number of particles sufficient for characterizing their statistical features during Ostwald ripening.The model can incorporate size dependence of coherency loss,metastability of coherent particles,and effectively incorporate the underlying mechanisms of coherency loss by introducing a so-called differential energy criterion.The model is applied to simulate coarsening of Al3Sc precipitates in aluminum alloy and comprehensively compared with experiments.Our results clearly show how the particle size distribution is changed during coherency loss and affects the coarsening rate.展开更多
Modeling of ductile fracture in polycrystalline structures is challenging,since it requires integrated modeling of cracks,crystal plasticity,and grains.Here we extend the typical phase-field framework to the situation...Modeling of ductile fracture in polycrystalline structures is challenging,since it requires integrated modeling of cracks,crystal plasticity,and grains.Here we extend the typical phase-field framework to the situations with constraints on the order parameters,and formulate two types of phase-field models on ductile fracture.The Type-Ⅰ model incorporates three sets of order parameters,which describe the distributions of cracks,plastic strain,and grains,respectively.Crystal plasticity is employed within grain interiors accommodated by J_(2)plasticity at grain boundaries.The applications of the Type-Ⅰ model to single crystals and bicrystals demonstrate the influences of grain orientations and grain boundaries on crack growth.In the Type-Ⅱ model,J_(2)plasticity is assumed for the whole system and grain structures are neglected.Taking advantage of the efficiency of the fast Fourier transform,our Type-Ⅱ model is employed to study low cycle fatigue.Crack closure and striation-like patterning of plastic strain are observed in the simulations.Crack growth rate is analyzed as a function of the J-integral,and the simulated fatigue life as a function of plastic strain agrees with the Coffin–Manson relation without a priori assumption.展开更多
We study the K-state phenomenon in the NiCoCr medium-entropy alloy using first-principles techniques jointly with the efficient Wang–Landau Monte Carlo and simulated annealing algorithms.Our theoretical results succe...We study the K-state phenomenon in the NiCoCr medium-entropy alloy using first-principles techniques jointly with the efficient Wang–Landau Monte Carlo and simulated annealing algorithms.Our theoretical results successfully explain the existence of the peak around 940 K in the experimental specific heat curve that characterizes the K-state phenomenon and give a fine picture of its atomic origin.The peak is caused by the maximum change of the local configurations characterized by the short-range-order(SRO)parameters at that temperature.展开更多
基金Research performed by Leidos Research Support Team staff was conducted under the RSS contract 89243318CFE000003This research was supported in part by an appointment to the U.S.Department of Energy(DOE)Postgraduate Research Program at the National Energy Technology Laboratory(NETL)administered by the Oak Ridge Institute for Science and EducationThis research used resources of Oak Ridge National Laboratory’s Compute and Data Environment for Science(CADES)and the Oak Ridge Leadership Computing Facility,which is supported by the Office of Science of the U.S.Department of Energy under Contract No.DE-AC05-00OR22725.
文摘The empirical rules for the prediction of solid solution formation proposed so far in the literature usually have very compromised predictability.Some rules with seemingly good predictability were,however,tested using small data sets.Based on an unprecedented large dataset containing 1252 multicomponent alloys,machine-learning methods showed that the formation of solid solutions can be very accurately predicted(93%).The machine-learning results help identify the most important features,such as molar volume,bulk modulus,and melting temperature.
文摘In this research,a Graphical Processing Unit(GPU)accelerated Discrete Element Method(DEM)code was developed and coupled with the Computational Fluid Dynamic(CFD)software MFiX to simulate granular and multiphase flows with heat transfers and chemical reactions.The Fortran-based CFD solver was coupled with the CUDA/C++based DEM solver through inter-process pipes.The speedup to the CPU version of MFiX-DEM is about 130-243 folds in the simulation of particle packings.In fluidized bed simulations,the DEM computation time is reduced from 91%to 17%with a speedup of 78 folds.The simulation of Geldart A particle fluidization revealed a similar level of importance of both fluid and particle coarse-graining.The filtered drag derived from the two-fluid model is suitable for Euler-Lagrangian simulations with both fluid and particle coarse-graining.It overcorrects the influence of sub-grid structures if used for simulations with only fluid coarse-graining.
基金supported by the Office of Nuclear Energy of Department of Energy(grant No.DE-NE0008807).
文摘Polysiloxane coatings on yttria stabilized zirconia(YSZ)microspheres of 500μm were simulated in a spout fluidized bed coater using Multiphase Flow with Interface Exchange-Discrete Element Modelling(MFiX-DEM).Two different coater configurations were developed to study the influence of gas velocity and its distribution on particle dynamics.The presence of the Wurster tube not only enhances the dis-tribution but also increases the overall residence time of the particles.Investigations were also carried out with different Wurster tube positions(normal,10%and 20%lowered from its initial position).Among these,20%lowered Wurster tube position demonstrated the most effective coating process.The effects of gas inlet pressure on the average gas velocity and the distribution of particles were analyzed.More than 97%of the particles can be retained.The derived results,including average gas velocity,particle retention percentage,and distribution of particles with gas velocity,are being used to guide the experimental work in obtaining defect-free coatings for YSZ microspheres.
文摘This article presents the development and validation of the Superquadric Discrete Element Method(SuperDEM)for non-spherical particle simulation using a superquadric particle method in open-source CFD suite MFiX.A superquadric particle-particle contact algorithm with accelerating and stabilizing strategy was developed.A superquadric particle-arbitrary wall contact algorithm was developed,which enables the simulation in complex geometry.The solver was validated by comparing with experimental data generated in this study or available in the literature.Tests include cylinder contacting with a wall,static packing of M&M chocolate candies in a cylindrical container,static packing of cylinders in a cylindrical container,dynamic angle of repose of cylinders in a rotating drum,and discharging of chocolate candies from a hopper.Besides,MPI parallelization of the solver was implemented and the parallel performance of the solver using MPI was assessed through large-scale simulations of 1 million,10 million,and 100 million particles on up to 6800 cores,which demonstrates that the SuperDEM solver has great potential for industrial-scale systems simulation.
文摘An unknown in coupled Eulerian-Lagrangian models for particle flow,such as CFD-DEM,which has received fairly little attention in the literature to date is the size of the filter width in the transfer kernel.This work provides a preliminary glimpse at how this parameter can influence the solution in cold-flow,unbounded fluidization.Comparison to previously published direct numerical simulation data is used to suggest an appropriate range for this parameter.
基金This technical effort was performed in support of the Cross-Cutting Technologies Program of the National Energy Technology Laboratory(NETL)under the RSS contract 89243318CFE000003The research was executed through NETL Research&Innovation Center’s project coordinated by David E.Alman and was specifically under the advanced alloy development FWP led by Drs.David Alman and Jeffrey A.Hawk and in part through the XMAT project.This work partially used the Extreme Science and Engineering Discovery Environment(XSEDE),which is supported by National Science Foundation grant number ACI-1548562.
文摘A phase-field model is proposed to simulate coherency loss coupled with microstructure evolution.A special field variable is employed to describe the degree of coherency loss of each particle and its evolution is governed by a Ginzburg-Landau type kinetic equation.For the sake of computational efficiency,a flood-fill algorithm is introduced that can drastically reduce the required number of field variables,which allows the model to efficiently simulate a large number of particles sufficient for characterizing their statistical features during Ostwald ripening.The model can incorporate size dependence of coherency loss,metastability of coherent particles,and effectively incorporate the underlying mechanisms of coherency loss by introducing a so-called differential energy criterion.The model is applied to simulate coarsening of Al3Sc precipitates in aluminum alloy and comprehensively compared with experiments.Our results clearly show how the particle size distribution is changed during coherency loss and affects the coarsening rate.
文摘Modeling of ductile fracture in polycrystalline structures is challenging,since it requires integrated modeling of cracks,crystal plasticity,and grains.Here we extend the typical phase-field framework to the situations with constraints on the order parameters,and formulate two types of phase-field models on ductile fracture.The Type-Ⅰ model incorporates three sets of order parameters,which describe the distributions of cracks,plastic strain,and grains,respectively.Crystal plasticity is employed within grain interiors accommodated by J_(2)plasticity at grain boundaries.The applications of the Type-Ⅰ model to single crystals and bicrystals demonstrate the influences of grain orientations and grain boundaries on crack growth.In the Type-Ⅱ model,J_(2)plasticity is assumed for the whole system and grain structures are neglected.Taking advantage of the efficiency of the fast Fourier transform,our Type-Ⅱ model is employed to study low cycle fatigue.Crack closure and striation-like patterning of plastic strain are observed in the simulations.Crack growth rate is analyzed as a function of the J-integral,and the simulated fatigue life as a function of plastic strain agrees with the Coffin–Manson relation without a priori assumption.
基金This research used resources of the Oak Ridge Leadership Computing Facility,which is supported by the Office of Science of the U.S.Department of Energy under Contract No.DE-AC05-00OR22725M.C.G.acknowledges the support of the US Department of Energy’s Fossil Energy Crosscutting Technology Research Program at National Energy Technology Laboratory under the RSS contract 89243318CFE000003.
文摘We study the K-state phenomenon in the NiCoCr medium-entropy alloy using first-principles techniques jointly with the efficient Wang–Landau Monte Carlo and simulated annealing algorithms.Our theoretical results successfully explain the existence of the peak around 940 K in the experimental specific heat curve that characterizes the K-state phenomenon and give a fine picture of its atomic origin.The peak is caused by the maximum change of the local configurations characterized by the short-range-order(SRO)parameters at that temperature.
