We use non-equilibrium molecular dynamics simulations to calculate the self-diffusion coefficient, D, of a Lennard Jones fluid over a wide density and temperature range. The change in self-diffusion coefficient with t...
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We use non-equilibrium molecular dynamics simulations to calculate the self-diffusion coefficient, D, of a Lennard Jones fluid over a wide density and temperature range. The change in self-diffusion coefficient with temperature decreases by increasing density. For density ρ＊ = ρσ3 = 0.84 we observe a peak at the value of the self-diffusion coefficient and the critical temperature T＊ = kT/ε = 1.25. The value of the self-diffusion coefficient strongly depends on system size. The data of the self-diffusion coefficient are fitted to a simple analytic relation based on hydrodynamic arguments. This correction scales as N-α, where α is an adjustable parameter and N is the number of particles. It is observed that the values of a 〈 1 provide quite a good correction to the simulation data. The system size dependence is very strong for lower densities, but it is not as strong for higher densities. The self-diffusion coefficient calculated with non-equilibrium molecular dynamic simulations at different temperatures and densities is in good agreement with other calculations fronl the literature.
Boiling is a very complex and illusive process with very high efficiency of heat *** many sub-processes in boiling phenomenon,gravity can be involved and play much important *** reveal its influence,long-term,steady m...
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Boiling is a very complex and illusive process with very high efficiency of heat *** many sub-processes in boiling phenomenon,gravity can be involved and play much important *** reveal its influence,long-term,steady microgravity are ***,the opportunity is much ***,ground-based short-term microgravity experiment becomes an attractive alternative. Experiments of transient pool boiling of highly subcooled FC-72 on a smooth silicon chip with the dimensions of 10×10x0.5 mm3 were studied in short-term microgravity condition utilizing the drop tower *** heating currents were switched on near the release of the drop *** bubble behaviors and heat transfer of air-dissolved FC-72 on the silicon chip were obtained at the bulk
An empirical corrosion model for SS316L in simulated proton exchange membrane fuel cell (PEMFC) environments is developed based on systematic experimental data on the effects of various factors, such as acidity, fluor...
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Thermal impact of the parallel laying of gas and oil pipelines remains unclear though that of two oil pipelines has been relatively well studied. A numerical simulation method combined by finite volume and finite diff...
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Thermal impact of the parallel laying of gas and oil pipelines remains unclear though that of two oil pipelines has been relatively well studied. A numerical simulation method combined by finite volume and finite difference was used to investigate the complex heat transfer in three typical parallel laying patterns between gas and oil pipelines: hot oil pipeline with cold gas pipeline;cold oil pipeline with hot gas pipeline and hot oil pipeline with hot gas pipeline. In terms of these three different parallel laying cases, the present paper analyzed characteristics of the maximum differential temperature range and thermal distribution of oil/gas temperatures at different intervals along pipelines relative to the single laying. The numerical simulation results can provide some guidelines for designs and safe operations of the parallel laying of oil/gas pipelines.
In this paper, a coupling lattice Boltzmann (LB) model for simulating thermal flows on the standard two-dimensional nine-velocity (D2Q9) lattice is developed in the framework of the double-distribution-function (DDF) ...
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In this paper, a coupling lattice Boltzmann (LB) model for simulating thermal flows on the standard two-dimensional nine-velocity (D2Q9) lattice is developed in the framework of the double-distribution-function (DDF) approach in which the viscous heat dissipation and compression work are considered. In the model, a density distribution function is used to simulate the flow field, while a total energy distribution function is employed to simulate the temperature field. The discrete equilibrium density and total energy distribution functions are obtained from the Hermite expansions of the corresponding continuous equilibrium distribution functions. The pressure given by the equation of state of perfect gases is recovered in the macroscopic momentum and energy equations. The coupling between the momentum and energy transports makes the model applicable for general thermal flows such as non-Boussinesq flows, while the existing DDF LB models on standard lattices are usually limited to Boussinesq flows in which the temperature variation is small. Meanwhile, the simple structure and general features of the DDF LB approach are retained. The model is tested by numerical simulations of thermal Couette flow, attenuation-driven acoustic streaming, and natural convection in a square cavity with small and large temperature differences. The numerical results are found to be in good agreement with the analytical solutions and/or other numerical results reported in the literature.
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