An Improved Lattice Boltzmann Method for Simulating High-Conductivity-Ratio Conjugate Heat Transfer

This paper presents an improved lattice Boltzmann method for simulating conjugate heat transfer. In conventional lattice Boltzmann methods, the coupling between thermal conductivity and relaxation time limits numerical stability for high-conductivity solids. To address this challenge, the proposed model introduces a correction source term to decouple the physical thermal conductivity from the relaxation parameter. The method is validated through representative test cases including heat conduction in a two-layered annulus, conjugate heat transfer in a layered channel, and natural convection in a square enclosure with discrete solid blocks. Numerical results demonstrate that the algorithm possesses second-order spatial accuracy. Moreover, the results show good agreement with the literature benchmarks at low thermal conductivity ratios and confirm the capability of the method to simulate conjugate heat transfer at high thermal conductivity ratios up to 1000.