Numerical simulation of natural convection heat transfer in a horizontal annulus with discrete heating using mesh-free lattice-Boltzmann method

This study investigates the natural convection heat transfer in a horizontal annulus with discrete heating using a mesh-free lattice Boltzmann method. The lattice Boltzmann method has become an alternative to the conventional computational fluid dynamics methods for simulation of complex fluid flows. The major advantages of the lattice Boltzmann method are the explicit feature of the governing equation, easy for parallel computation, and simple implementation of boundary conditions on curved boundaries. Despite well viability of standard LBM for the uniform mesh, it cannot be directly applied to problems with complex geometry and non-uniform mesh. An efficient method for removing this limitation is to use Taylor series expansion and least squares-based LBM (TLLBM). The final form of the TLLBM is an algebraic formulation with no limitation on the mesh structure. This method can also be applied to any lattice velocity model. In the present work, the TLLBM with D2Q9 lattice model is used to simulate natural convection heat transfer in a horizontal annulus with discrete heating. The effects of Rayleigh number and different arrangement of two heat source-sink pairs on the fluid flow and heat transfer characteristics are investigated.