More than half a century after its first formulation by Reiss, Frisch and Lebowitz in 1959, scaled particle theory(SPT) has proven its immense usefulness and has become one of the most successful theories in liquid ph...More than half a century after its first formulation by Reiss, Frisch and Lebowitz in 1959, scaled particle theory(SPT) has proven its immense usefulness and has become one of the most successful theories in liquid physics. In recent years, we have strived to extend SPT to fluids confined in a variety of random porous matrices. In this article, we present a timely review of these developments. We have endeavored to present a formulation that is pedagogically more accessible than those presented in various original papers, and we hope this benefits newcomers in their research work. We also use more consistent notations for different cases. In addition, we discuss issues that have been scarcely considered in the literature, e.g., the one-fluid structure of SPT due to the isomorphism between the equation of state for a multicomponent fluid and that for a one-component fluid or the pure-confinement scaling relation that provides a connection between a confined and a bulk fluid.展开更多
Nonequilibrium molecular dynamics(NEMD) simulations have provided unique insights into the nanoscale behaviour of lubricants under shear. This review discusses the early history of NEMD and its progression from a tool...Nonequilibrium molecular dynamics(NEMD) simulations have provided unique insights into the nanoscale behaviour of lubricants under shear. This review discusses the early history of NEMD and its progression from a tool to corroborate theories of the liquid state, to an instrument that can directly evaluate important fluid properties, towards a potential design tool in tribology. The key methodological advances which have allowed this evolution are also highlighted. This is followed by a summary of bulk and confined NEMD simulations of liquid lubricants and lubricant additives, as they have progressed from simple atomic fluids to ever more complex, realistic molecules. The future outlook of NEMD in tribology, including the inclusion of chemical reactivity for additives, and coupling to continuum methods for large systems, is also briefly discussed.展开更多
The existence of confining walls limits the prediction accuracy of nanoconfined fluids using macroscopic equations of state(EOSs);moreover,appropriate EOSs for multicomponent mixture fluids in nanoconfined spaces are ...The existence of confining walls limits the prediction accuracy of nanoconfined fluids using macroscopic equations of state(EOSs);moreover,appropriate EOSs for multicomponent mixture fluids in nanoconfined spaces are missing.Here,we derive the EOS of multicomponent mixture fluids confined in nanospaces at high temperatures and pressures,mainly considering the nanoconfinement effect and the competitive adsorption effect between different components.Then,the EOSs are validated through comparison with the molecular dynamics-simulated Pv T data of CO_(2)/H_(2)O mixtures in graphite nanoslits.To consider the above effects,we derive two EOSs via two modeling methods:EOS I is obtained through modification of the actual component occupation volume in the Peng-Robinson equation of state(PR EOS)by fitting the binary component interaction coefficient and the number of adsorbed molecules according to a selectivity coefficient,while EOS II is obtained by considering the decreased pressure of the fluids in PR EOS by adding an attractive term between components and walls.With the simulation results as a benchmark,the two EOSs exhibited good prediction accuracies under low CO_(2) concentrations,and generally,EOS II was more accurate than EOS I.This study fills the gap in the EOSs of nanoconfined mixture fluids,and the obtained equations can help to further describe the thermodynamic properties of confined mixture fluids.展开更多
文摘More than half a century after its first formulation by Reiss, Frisch and Lebowitz in 1959, scaled particle theory(SPT) has proven its immense usefulness and has become one of the most successful theories in liquid physics. In recent years, we have strived to extend SPT to fluids confined in a variety of random porous matrices. In this article, we present a timely review of these developments. We have endeavored to present a formulation that is pedagogically more accessible than those presented in various original papers, and we hope this benefits newcomers in their research work. We also use more consistent notations for different cases. In addition, we discuss issues that have been scarcely considered in the literature, e.g., the one-fluid structure of SPT due to the isomorphism between the equation of state for a multicomponent fluid and that for a one-component fluid or the pure-confinement scaling relation that provides a connection between a confined and a bulk fluid.
基金the Engineering and Physical Sciences Research Council (EPSRC) for financial support through a Doctoral Prize Fellowship
文摘Nonequilibrium molecular dynamics(NEMD) simulations have provided unique insights into the nanoscale behaviour of lubricants under shear. This review discusses the early history of NEMD and its progression from a tool to corroborate theories of the liquid state, to an instrument that can directly evaluate important fluid properties, towards a potential design tool in tribology. The key methodological advances which have allowed this evolution are also highlighted. This is followed by a summary of bulk and confined NEMD simulations of liquid lubricants and lubricant additives, as they have progressed from simple atomic fluids to ever more complex, realistic molecules. The future outlook of NEMD in tribology, including the inclusion of chemical reactivity for additives, and coupling to continuum methods for large systems, is also briefly discussed.
基金supported by the National Natural Science Foundation of China for the Basic Science Center Program for Ordered Energy Conversion(Grant Nos.51888103,and 52222606)。
文摘The existence of confining walls limits the prediction accuracy of nanoconfined fluids using macroscopic equations of state(EOSs);moreover,appropriate EOSs for multicomponent mixture fluids in nanoconfined spaces are missing.Here,we derive the EOS of multicomponent mixture fluids confined in nanospaces at high temperatures and pressures,mainly considering the nanoconfinement effect and the competitive adsorption effect between different components.Then,the EOSs are validated through comparison with the molecular dynamics-simulated Pv T data of CO_(2)/H_(2)O mixtures in graphite nanoslits.To consider the above effects,we derive two EOSs via two modeling methods:EOS I is obtained through modification of the actual component occupation volume in the Peng-Robinson equation of state(PR EOS)by fitting the binary component interaction coefficient and the number of adsorbed molecules according to a selectivity coefficient,while EOS II is obtained by considering the decreased pressure of the fluids in PR EOS by adding an attractive term between components and walls.With the simulation results as a benchmark,the two EOSs exhibited good prediction accuracies under low CO_(2) concentrations,and generally,EOS II was more accurate than EOS I.This study fills the gap in the EOSs of nanoconfined mixture fluids,and the obtained equations can help to further describe the thermodynamic properties of confined mixture fluids.
