Molecular Dynamics Simulation Of Thermal Conduction Strengthening And Flow Characteristics Of Cu-Ar Nanofluids

Nanofluid is a kind of solid-liquid suspension formed by adding nano crystalline or amorphous solid particles into water,heat transfer oil,glycol and other liquid heat transfer media.Its excellent heat transfer effect makes it one of the hot spots in the past 15 years.Because the size of nanoparticles is very close to the level of atoms and molecules,van der Waals force,electrostatic force and Brownian force can not be ignored.Molecular dynamics simulation has become an important method to study nano scale problems.In this paper,argon based nanofluids are used as the main research object,and the L-J potential energy function is used to build the Cu ar nanofluid model.In this paper,the variation of thermal conductivity and shear viscosity of Cu ar nanofluids is studied.Thermal conductivity is one of the important factors affecting the enhanced heat transfer of fluids,and shear viscosity mainly reflects the rheological properties of fluids.This paper uses molecular dynamics simulation methods to establish a corresponding model,focusing on the enhancement of nano-fluid thermal conductivity and The relationship between the volume fraction and particle size change of nanoparticles;the effects of temperature,particle size and volume fraction of nano particles on the rheological properties of nanofluids were studied,from the diffusion coefficient,mean square displacement,and radial distribution of the particles Function and other micro-angles analyze the reasons that affect the macro-physical properties of nanofluids.After conducting a simulation study on the thermal conductivity of Cu-Ar nanofluids,it was found that the changes in the volume fraction and particle size of Cu nanoparticles changed the interaction between Cu nanoparticles and Cu nanoparticles,as well as the base liquid Ar and Cu nanoparticles.To some extent,the process of energy transfer in nanofluids has been changed.The larger the volume fraction of nanoparticles,the higher the thermal conductivity of the nanofluid,and the growth trend tends to be linear;the larger the particle size,the lower the thermal conductivity of the nanofluid,and the growth trend becomes non-linear.The simulation of the shear viscosity of Cu-Ar nanofluids shows that as the volume fraction increases,the shear viscosity of the nanofluid graduallyincreases,and the magnitude of the increase in shear viscosity becomes higher and higher.In the following,the relative viscosity obtained by the NEMD method is more consistent with the classic suspension model than the results obtained by the EMD method.As the volume fraction increases,the simulation results change more significantly than the predicted value of the model.Temperature is one of the main factors affecting the rheological properties of nanofluids.As the temperature increases,the shear viscosity of nanofluids gradually decreases,and the trend of change gradually becomes non-linear.The increase of temperature makes the movement of atoms inside the nanofluid more frequent.For a nanofluid with a volume fraction of 3%,the diffusion coefficient at the temperature of 105 K is increased by about 34% compared to 85 K.Combined with molecular dynamics theory,the effects of temperature,volume fraction and particle size on the thermal conductivity and rheological properties of nanofluids are analyzed,which is of certain guiding significance for the development of nanofluids with good thermodynamic and rheological properties.