The Experts below are selected from a list of 29361 Experts worldwide ranked by ideXlab platform

Ping Cheng - One of the best experts on this subject based on the ideXlab platform.

  • a new lattice boltzmann model for solid liquid phase change
    International Journal of Heat and Mass Transfer, 2013
    Co-Authors: Rongzong Huang, Ping Cheng
    Abstract:

    Abstract The solid–liquid phase change problems were solved by the lattice Boltzmann method in this paper. By modifying the Equilibrium Distribution Function for the temperature, a new approach was developed to treat the latent-heat source term. As compared with the previous work, the approach developed in this paper could avoid iteration steps or solving a group of linear equations, which guaranteed this approach’s high efficiency. The phase interface was traced by updating the total enthalpy, and the moving interface was treated by the immersed moving boundary scheme proposed by Noble and Torczynski for simulation of particulate suspensions. The approach was firstly validated by the problem of conduction-induced melting in a semi-infinite space, and good agreement with the analytical result was obtained. Then it was used to simulate melting problems coupled with natural convection, which demonstrated that the approach could produce consistent results as compared with other numerical method.

Dongliang Zhang - One of the best experts on this subject based on the ideXlab platform.

  • an improved lattice boltzmann method for solid liquid phase change in porous media under local thermal non Equilibrium conditions
    International Journal of Heat and Mass Transfer, 2017
    Co-Authors: Fangbao Tian, Zhenqian Chen, Dongliang Zhang
    Abstract:

    Abstract This paper presents an improved lattice Boltzmann (LB) method to simulate solid-liquid phase change with natural convection in porous media under local thermal non-Equilibrium (LTNE) conditions. In this method, three Distribution Functions are respectively adopted for flow field, and temperature field of the PCM and solid matrix. Different from previous models, the present model for temperature field incorporates the total enthalpy and a free parameter in the Equilibrium Distribution Function, and thus could have high computational efficiency by avoiding iteration procedure to deal with phase change. The present model is validated by the melting with natural convection in a square cavity filled with a metal foam. It is found that the numerical results are in good agreement with other numerical results, and the present method could preserve higher accuracy due to numerical diffusion reduction through keeping the relaxation time at around unity as well as tuning the free parameters properly.

Peter V Coveney - One of the best experts on this subject based on the ideXlab platform.

  • Mesoscopic dynamics of Voronoi fluid particles
    Journal of Physics A: Mathematical and General, 2002
    Co-Authors: Mar Serrano, Gianni De Fabritiis, Pep Español, Eirik Grude Flekkøy, Peter V Coveney
    Abstract:

    We compare and contrast two recently reported mesoscopic fluid particle models based on a two-dimensional Voronoi tessellation. Both models describe a Newtonian fluid at mesoscopic scales where fluctuations are important. From the requirement of thermodynamic consistency, the Equilibrium Distribution Function is given through the Einstein Distribution Function. We compute from the Einstein Distribution the Equilibrium Distribution Function for a single fluid particle. We observe excellent agreement between the simulation results for the proposed models and the theoretical Distribution Function.

  • inverse chapman enskog derivation of the thermohydrodynamic lattice bgk model for the ideal gas
    International Journal of Modern Physics C, 1998
    Co-Authors: Bruce M. Boghosian, Peter V Coveney
    Abstract:

    A thermohydrodynamic lattice-BGK model for the ideal gas was derived by Alexander et al. in 1993, and generalized by McNamara et al. in the same year. In these works, particular forms for the Equilibrium Distribution Function and the transport coefficients were posited and shown to work, thereby establishing the sufficiency of the model. In this paper, we rederive the model from a minimal set of assumptions, and thereby show that the forms assumed for the shear and bulk viscosities are also necessary, but that the form assumed for the thermal conductivity is not. We derive the most general form allowable for the thermal conductivity, and the concomitant generalization of the Equilibrium Distribution. In this way, we show that it is possible to achieve variable (albeit density-dependent) Prandtl number even within a single-relaxation-time lattice-BGK model. We accomplish this by demanding analyticity of the third moments and traces of the fourth moments of the Equilibrium Distribution Function. The method of derivation demonstrates that certain undesirable features of the model — such as the unphysical dependence of the viscosity coefficients on temperature — cannot be corrected within the scope of lattice-BGK models with constant relaxation time.

  • Inverse Chapman–Enskog Derivation of the Thermohydrodynamic Lattice-BGK Model for the Ideal Gas
    International Journal of Modern Physics C, 1998
    Co-Authors: Bruce M. Boghosian, Peter V Coveney
    Abstract:

    A thermohydrodynamic lattice-BGK model for the ideal gas was derived by Alexander et al. in 1993, and generalized by McNamara et al. in the same year. In these works, particular forms for the Equilibrium Distribution Function and the transport coefficients were posited and shown to work, thereby establishing the sufficiency of the model. In this paper, we rederive the model from a minimal set of assumptions, and thereby show that the forms assumed for the shear and bulk viscosities are also necessary, but that the form assumed for the thermal conductivity is not. We derive the most general form allowable for the thermal conductivity, and the concomitant generalization of the Equilibrium Distribution. In this way, we show that it is possible to achieve variable (albeit density-dependent) Prandtl number even within a single-relaxation-time lattice-BGK model. We accomplish this by demanding analyticity of the third moments and traces of the fourth moments of the Equilibrium Distribution Function. The method of derivation demonstrates that certain undesirable features of the model — such as the unphysical dependence of the viscosity coefficients on temperature — cannot be corrected within the scope of lattice-BGK models with constant relaxation time.

Rongzong Huang - One of the best experts on this subject based on the ideXlab platform.

  • a new lattice boltzmann model for solid liquid phase change
    International Journal of Heat and Mass Transfer, 2013
    Co-Authors: Rongzong Huang, Ping Cheng
    Abstract:

    Abstract The solid–liquid phase change problems were solved by the lattice Boltzmann method in this paper. By modifying the Equilibrium Distribution Function for the temperature, a new approach was developed to treat the latent-heat source term. As compared with the previous work, the approach developed in this paper could avoid iteration steps or solving a group of linear equations, which guaranteed this approach’s high efficiency. The phase interface was traced by updating the total enthalpy, and the moving interface was treated by the immersed moving boundary scheme proposed by Noble and Torczynski for simulation of particulate suspensions. The approach was firstly validated by the problem of conduction-induced melting in a semi-infinite space, and good agreement with the analytical result was obtained. Then it was used to simulate melting problems coupled with natural convection, which demonstrated that the approach could produce consistent results as compared with other numerical method.

Fangbao Tian - One of the best experts on this subject based on the ideXlab platform.

  • an improved lattice boltzmann method for solid liquid phase change in porous media under local thermal non Equilibrium conditions
    International Journal of Heat and Mass Transfer, 2017
    Co-Authors: Fangbao Tian, Zhenqian Chen, Dongliang Zhang
    Abstract:

    Abstract This paper presents an improved lattice Boltzmann (LB) method to simulate solid-liquid phase change with natural convection in porous media under local thermal non-Equilibrium (LTNE) conditions. In this method, three Distribution Functions are respectively adopted for flow field, and temperature field of the PCM and solid matrix. Different from previous models, the present model for temperature field incorporates the total enthalpy and a free parameter in the Equilibrium Distribution Function, and thus could have high computational efficiency by avoiding iteration procedure to deal with phase change. The present model is validated by the melting with natural convection in a square cavity filled with a metal foam. It is found that the numerical results are in good agreement with other numerical results, and the present method could preserve higher accuracy due to numerical diffusion reduction through keeping the relaxation time at around unity as well as tuning the free parameters properly.