| The transport coefficient,which is frequently employed in engineering applications,is a crucial parameter to explain the material’s physical characteristics and characterize its macroscopic transport qualities.To reliably measure and identify certain new materials using experimental methods,it can be challenging to estimate the transport coefficient of a simple fluid or a complicated fluid.As a result,researchers’focus has shifted to figuring out the fluid’s transfer coefficient and researching the elements that affect it.An efficient and practical way for figuring out the transport coefficients of fluids in various states has been made possible in recent years by the widespread use of molecular dynamics modeling techniques.In order to investigate the diffusion behavior of basic fluids and examine the impact of density and temperature on fluid diffusion and viscosity,this research will use molecular dynamics simulation.Initially,using the Enskog theory,it is possible to determine how density and temperature affect the hard sphere fluid’s self-diffusion coefficient,although the hard sphere model only takes into account the immediate impact of atom collisions.In actuality,atoms engage in intricate interactions.In this study,the effect of the LJ potential on atomic collision is taken into account,and the relationship between temperature and atomic diameter is examined using the Virial theorem in conjunction with the energy equipartition theory.The system’s diffusion will be impacted by the reduction in atoms’effective diameter caused by a rise in temperature.As a result,the self-diffusion coefficient is inversely proportional to the temperature.Second,the self-diffusion coefficient of atoms falls as system density rises.Density and the self-diffusion coefficient have a complicated relationship,though.In this study,molecular dynamics simulation is used to produce a semi-empirical formula.The dependency of LJ fluid on self-diffusion coefficient may be accurately stated when the lowered temperature is larger than 1.33 and the reduced density is in the region of0.1194-1.1942.The atomic diffusion stops and the LJ fluid transitions to glass if the decreased density is higher than 1.298.Then,a simulation of molecular dynamics was used to determine the viscosity of LJ fluid.The SE link was confirmed since these state points individually correlate to the self-diffusion coefficient.The relationship between lnη~*and ln D~*n~*at various temperatures was discovered.Although the slope of the curve varies depending on the temperature,it often remains close to 1,which is consistent with the SE relationship.As a result of the simulation,it was discovered that viscosity rises as density rises.The system’s viscosity progressively rises when the lowered density is less than 0.8.The viscosity rises sharply and quickly when the lowered density exceeds 0.8,which also happens to be the density at which the fluid transitions to glass. |
