On the finite-volume Lattice Boltzmann modeling of thermo-hydrodynamics

AbstractIn this paper, Thermal Finite-Volume Lattice Boltzmann Method is developed. To demonstrate the temperature field, the Double Distribution Function (DDF) of thermal lattice Boltzmann equation is used. The upwind biasing factors based on pressure and temperature are defined and applied as flux corrector in the thermo-hydrodynamic lattice Boltzmann equations. A consistent open and solid boundary treatment of flow is also addressed. The unknown energy distribution at the boundary cells are decomposed into its equilibrium and non-equilibrium parts. Then the non-equilibrium part is approximated with extrapolation of the non-equilibrium part of the populations at the neighboring nodes. This treatment enlarges the domain stability and led up to faster convergence. Two test cases namely, thermo-hydrodynamic in a backward-facing step and around a circular cylinder inserted within a backward-facing step are carried out. The results are compared with the available solutions in the technical literature

Numerical Nanofluid Simulation with Finite Volume Lattice-Boltzmann Enhanced Approach

In this paper, the finite volume Lattice-Boltzmann method is used to model the thermo-fluid behavior of nanofluid, in which nanoparticles are dispersed. The major internal and external forces including Brownian, repulsion and attracting DLVO, drag and buoyancy acting on nanoparticles are taken into account. All these forces make the thermal and dynamic mechanism inside the nanofluid improved. These models are established to simulate and enhance the heat transfer properties of nanoparticles in the CuO-H2O nanofluid as a test case. Also, convective heat transfer coefficient of the nanofluid is computed in different Reynolds numbers. The numerical approach is based on a modified and robust finite volume method

Simulating two-dimensional thermal channel flows by means of a lattice Boltzmann method with new boundary conditions

Thermal boundary conditions for a doubled-populations BGK model are introduced and numerically demonstrated. The unknown thermal distribution functions at the boundary are assumed to be equilibrium distribution functions, with a counter-slip internal energy density which is determined consistently with Dirichlet and/or Neumann boundary constraints. The hydrodynamic boundary conditions are adapted to situations of engineering interest, and viscous heating effects are taken in account. The method is used to simulate channel flows; numerical results and theoretical solutions are found in satisfactory agreement for both hydrodynamic and thermal fields. © 2003 Elsevier B.V. All rights reserved

Lattice Boltzmann methods for multiphase flow and phase-change heat transfer

Over the past few decades, tremendous progress has been made in the development of particle-based discrete simulation methods versus the conventional continuum-based methods. In particular, the lattice Boltzmann (LB) method has evolved from a theoretical novelty to a ubiquitous, versatile and powerful computational methodology for both fundamental research and engineering applications. It is a kinetic-based mesoscopic approach that bridges the microscales and macroscales, which offers distinctive advantages in simulation fidelity and computational efficiency. Applications of the LB method are now found in a wide range of disciplines including physics, chemistry, materials, biomedicine and various branches of engineering. The present work provides a comprehensive review of the LB method for thermofluids and energy applications, focusing on multiphase flows, thermal flows and thermal multiphase flows with phase change. The review first covers the theoretical framework of the LB method, revealing certain inconsistencies and defects as well as common features of multiphase and thermal LB models. Recent developments in improving the thermodynamic and hydrodynamic consistency, reducing spurious currents, enhancing the numerical stability, etc., are highlighted. These efforts have put the LB method on a firmer theoretical foundation with enhanced LB models that can achieve larger liquid-gas density ratio, higher Reynolds number and flexible surface tension. Examples of applications are provided in fuel cells and batteries, droplet collision, boiling heat transfer and evaporation, and energy storage. Finally, further developments and future prospect of the LB method are outlined for thermofluids and energy applications