A new dimensionless number is proposed for dynamic plastic deformation analysis of clamped circular plates under underwater explosion loads by introducing dimensional analysis method to the basic dynamical governing e...A new dimensionless number is proposed for dynamic plastic deformation analysis of clamped circular plates under underwater explosion loads by introducing dimensional analysis method to the basic dynamical governing equations of circular plates.The relation between dimensionless final plastic deformation of circular plates and the new dimensionless number is established based on massive underwater explosion test data.Meanwhile,comparative analysis was discussed with two other published dimensionless parameters which indicated the new dimensionless number proposed in this paper is more effective and extensive to predict the dynamic plastic response of circular plates under underwater explosion condition.展开更多
This study employs a data-driven methodology that embeds the principle of dimensional invariance into an artificial neural network to automatically identify dominant dimensionless quantities in the penetration of rod ...This study employs a data-driven methodology that embeds the principle of dimensional invariance into an artificial neural network to automatically identify dominant dimensionless quantities in the penetration of rod projectiles into semi-infinite metal targets from experimental measurements.The derived mathematical expressions of dimensionless quantities are simplified by the examination of the exponent matrix and coupling relationships between feature variables.As a physics-based dimension reduction methodology,this way reduces high-dimensional parameter spaces to descriptions involving only a few physically interpretable dimensionless quantities in penetrating cases.Then the relative importance of various dimensionless feature variables on the penetration efficiencies for four impacting conditions is evaluated through feature selection engineering.The results indicate that the selected critical dimensionless feature variables by this synergistic method,without referring to the complex theoretical equations and aiding in the detailed knowledge of penetration mechanics,are in accordance with those reported in the reference.Lastly,the determined dimensionless quantities can be efficiently applied to conduct semi-empirical analysis for the specific penetrating case,and the reliability of regression functions is validated.展开更多
Micromotors are widely used in cell operation,drug delivery and environmental decontamination due to their small size,low energy consumption and large propelling power.Compared to traditional Janus micromotor,the shel...Micromotors are widely used in cell operation,drug delivery and environmental decontamination due to their small size,low energy consumption and large propelling power.Compared to traditional Janus micromotor,the shell Janusmicromotor has better motion performance.However,the structural optimization of itsmotion performance is still unclear.The main factor restricting the motion performance of shell Janus micromotors is the drag forces.In the current work,theoretical analysis and numerical simulation were applied to analyze the drag forces of shell Janus micromotors.This study aims to design the optimum structure of shell Janus micromotors with minimum drag forces and obtain the magnitude of drag forces considering both the internal and external fluids of the shell Janus micromotors.Moreover,the influence of the motor geometry and Reynolds number on the drag coefficient was analyzed using numerical simulations.The results provide guidance for the optimum flow velocity,opening diameter and shell thickness to achieve minimum drag force.展开更多
By reduction to one dimensional, periodic as well as rotating pulse heat sources, investigation on heat transfer characteristics with rotating body is carried out. Similar to the fluid flow, a new set of dimensionless...By reduction to one dimensional, periodic as well as rotating pulse heat sources, investigation on heat transfer characteristics with rotating body is carried out. Similar to the fluid flow, a new set of dimensionless numbers, namely quasi-Peclet numbers Pe 1, Pe 2 and Biot number Bi composed of angular velocity ω , thermophysical parameter, and geometry size are proposed, and applied to the dimensionless equations. Simulation result shows that it plays a decisive role in the process of the heat transfer. However, more important is that the numerical simulation depicts the difference between microcosmic and macroscopic structures of the temperature distribution, and reveals the influence of the relative relation of the dimensionless criterion numbers upon heat transfer characteristics.展开更多
In contrast to classical dimensional analysis, discriminated dimensional analysis assumes that spatial coordinates are dimensionally independent of each other and allows other types of geometrical quantity to be used ...In contrast to classical dimensional analysis, discriminated dimensional analysis assumes that spatial coordinates are dimensionally independent of each other and allows other types of geometrical quantity to be used in the dimensional basis, such as surfaces and angles. As a consequence, discriminated dimensional analysis leads to a lower number of dimensional groups, which makes the solution more precise. Besides, these discriminated groups have a clear physical meaning in terms of force and energy balances. The paper introduces this technique and provides dimensional equations for the main quantities and physical parameters of the heat transfer and fluid flow fields. Two applications are presented to demonstrate the efficiency of this method.展开更多
The passage of a rising bubble through immiscible fluids is encountered in bath smelting.In order to investigate characteristics of bubble deformation in immiscible fluids,the bubble shape change at the interface and ...The passage of a rising bubble through immiscible fluids is encountered in bath smelting.In order to investigate characteristics of bubble deformation in immiscible fluids,the bubble shape change at the interface and the relationship between the bubble aspect ratio(E)and dimensionless number of forces were obtained.A three-dimensional model was established,and the free-floating behavior of a single bubble in immiscible fluids was numerically simulated by phase-field method.The simulation results are in good agreement with experimental results.The results indicate that when the bubble passes through the interface,the bubble shape is divided into four types in turn:“pear”,inverted“pear”,“convex”and“droplet”shape.In the lower liquid,the relationship of E to Weber number(We),Tadaki number(Ta),and Reynolds number(Re)is distributed between two intersecting lines.The relationship of E to Eötvös number(Eo),a dimensionless group,and Galilei number(Ga)is distributed near the lines with slopes of−3.325×10^(-5),−0.0855,and−8.73×10^(-4),respectively.In the upper liquid,the relationship of E to We,Ta,and Re is distributed between two parallel lines.Compared with gravity,the inertial force plays a leading role in the bubble shape in the lower and upper liquid.Compared with the viscous force,the surface tension dominates the bubble shape in the lower liquid.展开更多
Dynamic simulation of a double-skin façade(DSF)with computational fluid dynamics(CFD)can be challenging due to the lack of validated models and benchmarking datasets.Furthermore,there is a lack of consensus in th...Dynamic simulation of a double-skin façade(DSF)with computational fluid dynamics(CFD)can be challenging due to the lack of validated models and benchmarking datasets.Furthermore,there is a lack of consensus in the scientific community on what constitutes a successfully validated DSF model.The present review study identifies simulation trends and research gaps for DSFs simulated with CFD.Additionally,this article presents a series of CFD simulations in which key aspects of the DSF modelling are varied:2D or 3D modelling approaches,turbulence viscosity models(TVMs),radiation models,and wall function.These simulation results are compared to the empirical data(both temperature and velocity fields)of a benchmark test with laboratory-controlled boundary conditions.This analysis shows that using the k-εRNG model with enhanced wall treatment and surface-to-surface(S2S)radiation model yields the best results for the 2D case of natural convection flow.Moreover,it is shown that accounting for the velocity field in the validation process is essential to ensure the suitability of a model.Finally,the authors advocate for the use of selected dimensionless numbers to improve the comparability of the different DSF scientific studies.This would also help to identify relevant experimental datasets for validation and suitable CFD simulation settings for specific DSF cases.展开更多
A new neural network architecture,namely DimNet,was designed for correlating dimensionless quantities with power-law-like relations.Unlike common neural networks that are usually used as“black-boxes”,DimNet is inter...A new neural network architecture,namely DimNet,was designed for correlating dimensionless quantities with power-law-like relations.Unlike common neural networks that are usually used as“black-boxes”,DimNet is interpretable as it can be converted to an explicit algebraic piecewise power-law-like function.With DimNet,a data-driven,empirical model was developed to predict the pre-dryout heat transfer coefficient of flow boiling within microfin tubes.The model was trained on a database with 7349 experimental data points for 16 refrigerants,and then optimized by comparing different sets of dominant dimensionless quantities and by adjusting the network configuration.The model exhibits an overall mean-absolute-error of 13.8%and no systematic variation with respect to the salient parameters for most conditions.Besides being statistically accurate,the model captures parametric trends of the heat transfer coefficient.The excellent prediction performance of the model was attributed to the DimNet’s ability to automatically classify the data into optimal regions and simultaneously correlate the data of each region.Therefore,the DimNet architecture is inherently suitable for modeling complex heat transfer and flow problems where multiple distinct physical regimes exist,especially for problems where a power-law-like input–output relation is desired such as convective heat transfer.展开更多
The pyrolysis behaviors and temperature evolution history of lignocellulosic biomass(Beech,BH)were characterized using a novel pyrolysis model-C-DAEM.The simulation results were validated through corresponding experim...The pyrolysis behaviors and temperature evolution history of lignocellulosic biomass(Beech,BH)were characterized using a novel pyrolysis model-C-DAEM.The simulation results were validated through corresponding experimental data.Based on the simulation results,two distinct peaks were observed in the temperature difference between the surface and center(TDSC)curve,namely the thermal disturbance peak(TDP)and the pyrolysis reaction peak(PRP).The presence of TDP and PRP was confirmed by examining the heat flux ratio between the pyrolysis rate and the temperature rise rate.Moreover,the results indicated that three factors,namely heating temperature,particle size,and pyrolysis rate,influenced the relative intensity between TDP and PRP.By changing the values of each impact factor,conditions where TDP owns the same height with PRP were obtained under different working conditions.These findings have led to the development of a dimensionless number,naming the pyrolysis-heating surface-center number(PHSC number).This number could provide a comprehensive indication of the collective impact of the aforementioned factors when TDP and PRP exhibit equal peak heights.展开更多
基金supported by the National Natural Science Foundation of China(12402444)。
文摘A new dimensionless number is proposed for dynamic plastic deformation analysis of clamped circular plates under underwater explosion loads by introducing dimensional analysis method to the basic dynamical governing equations of circular plates.The relation between dimensionless final plastic deformation of circular plates and the new dimensionless number is established based on massive underwater explosion test data.Meanwhile,comparative analysis was discussed with two other published dimensionless parameters which indicated the new dimensionless number proposed in this paper is more effective and extensive to predict the dynamic plastic response of circular plates under underwater explosion condition.
基金supported by the National Natural Science Foundation of China(Grant Nos.12272257,12102292,12032006)the special fund for Science and Technology Innovation Teams of Shanxi Province(Nos.202204051002006).
文摘This study employs a data-driven methodology that embeds the principle of dimensional invariance into an artificial neural network to automatically identify dominant dimensionless quantities in the penetration of rod projectiles into semi-infinite metal targets from experimental measurements.The derived mathematical expressions of dimensionless quantities are simplified by the examination of the exponent matrix and coupling relationships between feature variables.As a physics-based dimension reduction methodology,this way reduces high-dimensional parameter spaces to descriptions involving only a few physically interpretable dimensionless quantities in penetrating cases.Then the relative importance of various dimensionless feature variables on the penetration efficiencies for four impacting conditions is evaluated through feature selection engineering.The results indicate that the selected critical dimensionless feature variables by this synergistic method,without referring to the complex theoretical equations and aiding in the detailed knowledge of penetration mechanics,are in accordance with those reported in the reference.Lastly,the determined dimensionless quantities can be efficiently applied to conduct semi-empirical analysis for the specific penetrating case,and the reliability of regression functions is validated.
基金the Fundamental Research Funds for the Central Universities(WUT:2019III075GX)the Open Foundation of Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics(Grant No.TAM201813).
文摘Micromotors are widely used in cell operation,drug delivery and environmental decontamination due to their small size,low energy consumption and large propelling power.Compared to traditional Janus micromotor,the shell Janusmicromotor has better motion performance.However,the structural optimization of itsmotion performance is still unclear.The main factor restricting the motion performance of shell Janus micromotors is the drag forces.In the current work,theoretical analysis and numerical simulation were applied to analyze the drag forces of shell Janus micromotors.This study aims to design the optimum structure of shell Janus micromotors with minimum drag forces and obtain the magnitude of drag forces considering both the internal and external fluids of the shell Janus micromotors.Moreover,the influence of the motor geometry and Reynolds number on the drag coefficient was analyzed using numerical simulations.The results provide guidance for the optimum flow velocity,opening diameter and shell thickness to achieve minimum drag force.
文摘By reduction to one dimensional, periodic as well as rotating pulse heat sources, investigation on heat transfer characteristics with rotating body is carried out. Similar to the fluid flow, a new set of dimensionless numbers, namely quasi-Peclet numbers Pe 1, Pe 2 and Biot number Bi composed of angular velocity ω , thermophysical parameter, and geometry size are proposed, and applied to the dimensionless equations. Simulation result shows that it plays a decisive role in the process of the heat transfer. However, more important is that the numerical simulation depicts the difference between microcosmic and macroscopic structures of the temperature distribution, and reveals the influence of the relative relation of the dimensionless criterion numbers upon heat transfer characteristics.
文摘In contrast to classical dimensional analysis, discriminated dimensional analysis assumes that spatial coordinates are dimensionally independent of each other and allows other types of geometrical quantity to be used in the dimensional basis, such as surfaces and angles. As a consequence, discriminated dimensional analysis leads to a lower number of dimensional groups, which makes the solution more precise. Besides, these discriminated groups have a clear physical meaning in terms of force and energy balances. The paper introduces this technique and provides dimensional equations for the main quantities and physical parameters of the heat transfer and fluid flow fields. Two applications are presented to demonstrate the efficiency of this method.
基金The research is supported by Yunnan Fundamental Research Projects(No.202101AT070120)National Natural Science Foundation of China(No.51966005).
文摘The passage of a rising bubble through immiscible fluids is encountered in bath smelting.In order to investigate characteristics of bubble deformation in immiscible fluids,the bubble shape change at the interface and the relationship between the bubble aspect ratio(E)and dimensionless number of forces were obtained.A three-dimensional model was established,and the free-floating behavior of a single bubble in immiscible fluids was numerically simulated by phase-field method.The simulation results are in good agreement with experimental results.The results indicate that when the bubble passes through the interface,the bubble shape is divided into four types in turn:“pear”,inverted“pear”,“convex”and“droplet”shape.In the lower liquid,the relationship of E to Weber number(We),Tadaki number(Ta),and Reynolds number(Re)is distributed between two intersecting lines.The relationship of E to Eötvös number(Eo),a dimensionless group,and Galilei number(Ga)is distributed near the lines with slopes of−3.325×10^(-5),−0.0855,and−8.73×10^(-4),respectively.In the upper liquid,the relationship of E to We,Ta,and Re is distributed between two parallel lines.Compared with gravity,the inertial force plays a leading role in the bubble shape in the lower and upper liquid.Compared with the viscous force,the surface tension dominates the bubble shape in the lower liquid.
文摘Dynamic simulation of a double-skin façade(DSF)with computational fluid dynamics(CFD)can be challenging due to the lack of validated models and benchmarking datasets.Furthermore,there is a lack of consensus in the scientific community on what constitutes a successfully validated DSF model.The present review study identifies simulation trends and research gaps for DSFs simulated with CFD.Additionally,this article presents a series of CFD simulations in which key aspects of the DSF modelling are varied:2D or 3D modelling approaches,turbulence viscosity models(TVMs),radiation models,and wall function.These simulation results are compared to the empirical data(both temperature and velocity fields)of a benchmark test with laboratory-controlled boundary conditions.This analysis shows that using the k-εRNG model with enhanced wall treatment and surface-to-surface(S2S)radiation model yields the best results for the 2D case of natural convection flow.Moreover,it is shown that accounting for the velocity field in the validation process is essential to ensure the suitability of a model.Finally,the authors advocate for the use of selected dimensionless numbers to improve the comparability of the different DSF scientific studies.This would also help to identify relevant experimental datasets for validation and suitable CFD simulation settings for specific DSF cases.
文摘A new neural network architecture,namely DimNet,was designed for correlating dimensionless quantities with power-law-like relations.Unlike common neural networks that are usually used as“black-boxes”,DimNet is interpretable as it can be converted to an explicit algebraic piecewise power-law-like function.With DimNet,a data-driven,empirical model was developed to predict the pre-dryout heat transfer coefficient of flow boiling within microfin tubes.The model was trained on a database with 7349 experimental data points for 16 refrigerants,and then optimized by comparing different sets of dominant dimensionless quantities and by adjusting the network configuration.The model exhibits an overall mean-absolute-error of 13.8%and no systematic variation with respect to the salient parameters for most conditions.Besides being statistically accurate,the model captures parametric trends of the heat transfer coefficient.The excellent prediction performance of the model was attributed to the DimNet’s ability to automatically classify the data into optimal regions and simultaneously correlate the data of each region.Therefore,the DimNet architecture is inherently suitable for modeling complex heat transfer and flow problems where multiple distinct physical regimes exist,especially for problems where a power-law-like input–output relation is desired such as convective heat transfer.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA29020600)the Special Research Assistant Project of the Chinese Academy of Sciences.
文摘The pyrolysis behaviors and temperature evolution history of lignocellulosic biomass(Beech,BH)were characterized using a novel pyrolysis model-C-DAEM.The simulation results were validated through corresponding experimental data.Based on the simulation results,two distinct peaks were observed in the temperature difference between the surface and center(TDSC)curve,namely the thermal disturbance peak(TDP)and the pyrolysis reaction peak(PRP).The presence of TDP and PRP was confirmed by examining the heat flux ratio between the pyrolysis rate and the temperature rise rate.Moreover,the results indicated that three factors,namely heating temperature,particle size,and pyrolysis rate,influenced the relative intensity between TDP and PRP.By changing the values of each impact factor,conditions where TDP owns the same height with PRP were obtained under different working conditions.These findings have led to the development of a dimensionless number,naming the pyrolysis-heating surface-center number(PHSC number).This number could provide a comprehensive indication of the collective impact of the aforementioned factors when TDP and PRP exhibit equal peak heights.
