Natural Convection from Inclined Square Cylinder Using Novel Flexible Forcing IB-LBM Approach

Abstract

A novel flexible forcing immersed boundary (IB) – lattice Boltzmann method (LBM) – is introduced in this article to simulate a complex natural convection phenomenon. In the conventional IB-LBM schemes, the explicit computation of force density may not ensure the exact no-slip velocity/no-jump temperature boundary condition. This produces unphysical streamline/isotherm penetration into the solid object. In the proposed formulation, an implicit approach is suggested to calculate the force density. Using a single Lagrangian correction term, the velocity and temperature boundary condition is accurately satisfied. The developed numerical scheme is applied to analyze a thermal flow situation in an annulus, formed by a hot inclined square cylinder and a cold enclosure. Flow pattern and heat transfer rate at different inclination angles (0<θ<45 deg) are investigated for a wide range of Rayleigh numbers (Ra) (103 – 106). The observed results confirm that the local heat transfer rate is influenced by θ and Ra.