Research On Complex Fluids By Energy Conservative Dissipative Particle Dynamics In The Meso-scale

With the development of science and technology,micro-electronic mechanical systems and other micro-devices have been widely used in many ways.The design and manufacture of micro-devices put forward higher requirements.Study of microelectromechanical system internal liquid flow with heat transfer mechanism has great academic value.However,the internal scale of the microelectromechanical system is mesoscopic.The macroscopic numerical simulation method based on continuous mechanics cannot simulate the problem accurately in this scale.The computational scale of the microcosmic method,such as molecular dynamics,is difficult to achieve this scale.Energy conservation dissipation particle dynamics(eDPD)is a coarse-grained molecular dynamics method.It not only studies complex fluid behavior at mesoscale scale,but also simulates complex heat transfer problems.It is an ideal method to study the complex fluid behavior with heat transfer at mesoscopic scale.This paper systematically illustrates the energy conservation dissipative particle dynamics method,and points out the main characteristics of the method,and analyzes its advantages in dealing with complex fluids.In this paper,we use eDPD to study the flow field and temperature field distribution of the rectangular array of circular flow around the channel.The distribution of the flow field and temperature field under different Reynolds numbers is analyzed.It is found that when the Reynolds number increases with the velocity of liquid flow increases the flow of heat more obvious.With the Reynolds number increasing,the fluid flows through the cylinder when there are different degrees of vortex,in the vortex zone to reduce the convective heat transfer rate decreases the local temperature peak.The eDPD was used to simulate the macromolecular chain of the microchannel.The velocity distribution,the stress distribution,the temperature distribution,the centroid distribution of the polymer chains and the instantaneous position of the polymer chains were analyzed under different polymer chain concentration,temperature and driving force.It is found that the polymer chain is far from the wall distribution,and the temperature difference between the polymer chain and the surrounding temperature is the result.The distribution of the polymer chain will change under the action of the floating force.With the increase of the driving force in the channel,the impact is gradually reduced.In the channel due to the speed distribution of uneven velocity of the local temperature distribution changes significantly,convective heat transfer phenomenon is obvious.The change of temperature and the concentration of polymer chains have little effect on the shear stress distribution,which has a great influence on the normal stress in the flow direction.