Simulation Of Nanofluids Heat Transfer Enhancement And Flow Characteristics With LBM

As an innovative heat transfer substance, nanofluid can effectively enhance the heat transfer performance of the device and make the device more compact with high efficiency. The conwection of nanofluid will be widely applied in the field of vehicle, spaceflight, voyage, shipping and electron。 The good performance of nanofluids makes it different from the large particle solid-liquid mixture, which makes nanofluids have broad prospects in the strengthening of the heat exchanger and practical application. The flow and heat transfer characteristics of nanofluids are simulated in this paper with two-component LBM method.As a mesoscopic method between the macroscopic fluid dynamics and the molecule dynamics, the method solve the problem of fluid flow by the migration and collision of particles based on the particles distribution function. Lattice Boltzmann method has many unique advantages compared to the traditional computational hydrodynamics methods, such as high efficiency, easily handle boundary condition and absolutely parallel computation. It is easy to understand and to write program. An important advantage of the Lattice Boltzmann method is that microscopic physical interactions between different phase particles can be conveniently incorporated into the numerical model, which is lacked in the conventional methods, so that it could supply an effective way to investigate multiphase flow and complex boundary condition problems. This article describes the basic theory of LBM and some boundary processing format which is commonly used and two-component LBM is presented in detail.Some basic characteristics of nanofluids are introduced. Such as gravitation force, Brownian force, dispersion force arising from the interaction potential which act on the nanoparticles. According to different theories, this paper analyzes the effect factors that caused the chang of the dynamics and stability of nanofluids. Some models for calculating the parameters of nanofluids such as thermal conductivity, viscosity are introduced and the effect of volume fraction, nanoparticle size and temperature of nanofluids that caused the chang of conductivity and viscosity are qualitatively analyzed.The nature convection flow and heat transfer of nanofluids are simulated by two-component LBM. Analyzed the temperature distribution and flow characteristics of natural convection of nanofluids in a square cavity with temperature difference, and compared the heat exchange characteristics with pure fluid. The average Nusselt number (Nu) changing with volume fraction at different Ra number is obtained.