This study investigates the effect of nonuniform heating and temperature-dependent viscosity on transient free convective flow in a porous material adjacent to a semi-infinite upright plate.Such scenarios are relevant...This study investigates the effect of nonuniform heating and temperature-dependent viscosity on transient free convective flow in a porous material adjacent to a semi-infinite upright plate.Such scenarios are relevant to applications such as the cooling of electronic devices,solar energy systems,and geophysical processes.The governing equations are transformed into dimensionless form and subsequently solved using the CrankNicolson technique.The results reveal that velocity increases with increasing viscosity parameter(ζ=0,2,4)at all cross-sections,while the temperature decreases at x=0.25 and 0.5,but rises at x=0.75,with the maximum free-stream velocity occurring at x=0.75 forζ=2.Additionally,velocity and temperature attain their highest values near the plate,with the boundary layers growing over time.Eventually,both velocity and temperature stabilize,signifying the attainment of a steady-state condition.The local Nusselt number exhibits an increasing trend with increasing Darcy,Prandtl,and Grashof numbers,indicating improved heat transfer,while increasing viscosity contributes to a reduction in local skin friction.Moreover,nonuniform heating leads to the highest temperature at x=0.5,which decreases at x=0.75,and reaches its lowest value at x=0.25.展开更多
CONSPECTUS:Additive Manufacturing(AM)technology produces three-dimensional components in a layer-by-layer fashion and offers numerous advantages over conventional manufacturing processes.Driven by the growing needs of...CONSPECTUS:Additive Manufacturing(AM)technology produces three-dimensional components in a layer-by-layer fashion and offers numerous advantages over conventional manufacturing processes.Driven by the growing needs of diverse industrial sectors,this technology has seen significant advances on both scientific and engineering fronts.Fusion-based processes are the mainstream techniques for AM of metallic materials.As the metals go through melting and solidification during the printing processes,the final microstructure and hence the properties of the printed components are highly sensitive to the printing conditions and can be very different from those of the feedstock.It is critical to understand the process-microstructure-property relationship for the accelerated optimization of the processing conditions and certification of the printed components.While experimentation has been used widely to acquire a mechanistic understanding of this subject matter,numerical modeling has become increasingly helpful in achieving the same purpose.In this Account,the authors review their ongoing collaborative effort to establish a multiphysics modeling framework to predict the process-microstructure-property relationship in fusion-based metal AM processes.The framework includes three individual modules to simulate the dominating physics that dictate the process dynamics and microstructure evolution during printing as well as the responses of the printed microstructure to specific mechanical loadings.The process model uses the material properties and processing conditions as the inputs and simulates the laser-material interaction,multiphase thermo-fluid flow,and fluid-driven powder motion.It has successfully revealed the physical causes of depression zone shape variation as well as powder motion during the laser powder bed fusion process.The microstructure model uses the thermal history of the printing process and the material chemistry as the inputs and predicts the nucleation and growth of multiple grains in the multipass and multilayer printing processes.It has been used to understand the effects of inoculation and thermal conditions on grain texture evolution.The property models use microstructure data from simulations,experimental measurements,or statistical analyses as the inputs and leverage various computational tools to predict the mechanical response of the AM materials.These models have been used to quantitatively evaluate the effects of grain structure,residual strain,and pore and void defects on their properties and performance.While this and many other modeling works have significantly grown our collective knowledge of the process-microstructure-property relationship in fusion-based metal AM processes,efforts should be further invested in developing advanced theories and algorithms for the governing physics,leveraging data-driven approaches,accelerating simulation speed,and calibrating/validating models with controlled experimental measurements,among other aspects.展开更多
文摘This study investigates the effect of nonuniform heating and temperature-dependent viscosity on transient free convective flow in a porous material adjacent to a semi-infinite upright plate.Such scenarios are relevant to applications such as the cooling of electronic devices,solar energy systems,and geophysical processes.The governing equations are transformed into dimensionless form and subsequently solved using the CrankNicolson technique.The results reveal that velocity increases with increasing viscosity parameter(ζ=0,2,4)at all cross-sections,while the temperature decreases at x=0.25 and 0.5,but rises at x=0.75,with the maximum free-stream velocity occurring at x=0.75 forζ=2.Additionally,velocity and temperature attain their highest values near the plate,with the boundary layers growing over time.Eventually,both velocity and temperature stabilize,signifying the attainment of a steady-state condition.The local Nusselt number exhibits an increasing trend with increasing Darcy,Prandtl,and Grashof numbers,indicating improved heat transfer,while increasing viscosity contributes to a reduction in local skin friction.Moreover,nonuniform heating leads to the highest temperature at x=0.5,which decreases at x=0.75,and reaches its lowest value at x=0.25.
基金support provided by the National Science Foundation under Grant No.CMMI-2119671.
文摘CONSPECTUS:Additive Manufacturing(AM)technology produces three-dimensional components in a layer-by-layer fashion and offers numerous advantages over conventional manufacturing processes.Driven by the growing needs of diverse industrial sectors,this technology has seen significant advances on both scientific and engineering fronts.Fusion-based processes are the mainstream techniques for AM of metallic materials.As the metals go through melting and solidification during the printing processes,the final microstructure and hence the properties of the printed components are highly sensitive to the printing conditions and can be very different from those of the feedstock.It is critical to understand the process-microstructure-property relationship for the accelerated optimization of the processing conditions and certification of the printed components.While experimentation has been used widely to acquire a mechanistic understanding of this subject matter,numerical modeling has become increasingly helpful in achieving the same purpose.In this Account,the authors review their ongoing collaborative effort to establish a multiphysics modeling framework to predict the process-microstructure-property relationship in fusion-based metal AM processes.The framework includes three individual modules to simulate the dominating physics that dictate the process dynamics and microstructure evolution during printing as well as the responses of the printed microstructure to specific mechanical loadings.The process model uses the material properties and processing conditions as the inputs and simulates the laser-material interaction,multiphase thermo-fluid flow,and fluid-driven powder motion.It has successfully revealed the physical causes of depression zone shape variation as well as powder motion during the laser powder bed fusion process.The microstructure model uses the thermal history of the printing process and the material chemistry as the inputs and predicts the nucleation and growth of multiple grains in the multipass and multilayer printing processes.It has been used to understand the effects of inoculation and thermal conditions on grain texture evolution.The property models use microstructure data from simulations,experimental measurements,or statistical analyses as the inputs and leverage various computational tools to predict the mechanical response of the AM materials.These models have been used to quantitatively evaluate the effects of grain structure,residual strain,and pore and void defects on their properties and performance.While this and many other modeling works have significantly grown our collective knowledge of the process-microstructure-property relationship in fusion-based metal AM processes,efforts should be further invested in developing advanced theories and algorithms for the governing physics,leveraging data-driven approaches,accelerating simulation speed,and calibrating/validating models with controlled experimental measurements,among other aspects.
