The Theory And Application Of Dissipative Particle Dynamics With Energy Conservation

Dissipative particle dynamics(DPD),a particle-based meshless numerical simulation method,has a natural advantage for simulating flow phenomena at mesoscale scales.Compared with molecular dynamics(MD),DPD is a coarse-grained method.DPD has a higher computational efficiency as each DPD particle contains a group of actual atoms or molecules,so it can simulate the fluid in a larger space-time scale.In the traditional DPD method,the total energy of the system is not conserved after the collision,so that only the isothermal system is available during the simulating.Later,the energy of the particles is realized by introducing the internal energy of the particles,thus energy transfer between particles is realized.The dissipative particle dynamics with energy conservation is simply referred to as eDPD in the literatures.The main works are as follows:In this paper,the dissipative particle dynamics with energy conservation method is used to simulate the flow of poiseuille and the thermal conductivity in two-dimensional cavity.The kinematic viscosity and the thermal diffusivity are set to verify the accuracy of the algorithm and prove that it has high accuracy.Then,the thermal conductivity in the fins is simulated by the newly established eDPD model,and the temperature distribution in the fins under three different boundary conditions is obtained.In this paper,then,the natural convection problem in the cavity and the concentric ring is simulated by introducing the Bussianzque hypothesis to calculate the buoyancy force of the particle.The results are compared with the results obtained by the FV method,and it is found that the results are in good agreement.It is proved that the eDPD algorithm can correctly simulate the natural convection problem in different geometric models and has high precision.At the same time,this paper also simulates the natural convection problem in the back cavity,and analyzes the influence of the Rayleigh number and the position of the inner cavity on the convective heat transfer in the cavity.In this paper,the mixed convection problem driven by shear force and floating force is also studied.The eDPD method is used to simulate the flow and heat transfer in the cavity with moving wall and different temperature walls.It is found that the eDPD method can accurately capture the mixture convective flow details,it can reflect the different sizes and intensities of the circulation areas.In this paper,we study the influence of Richardson number and the position of low temperature wall on heat transfer.It can be seen from the simulation that the position of Richardson number and low temperature wall has a great influence on the flow and heat transfer in the cavity.