An improved ghost cell Immersed Boundary Method for conjugate mass and heat transport in fluid-particle systems

Computational Fluid Dynamics (CFD) is a powerful tool for in-depth studies of multiphase systems, such as packed bed reactors. However, the packed particles create computational challenges near the contact points due to limited resolution or low-quality cells. This study employs a structured Cartesian mesh with a ghost cell Immersed Boundary Method (IBM) to avoid the typical meshing problems for body-conforming meshes. This work compares a traditional IBM with two new approaches for conjugate heat transfer. Considering the analogy between mass and heat transport, our approach can readily be extended to mass transport. The traditional IBM gives reasonable results only with comparable fluid-solid properties but fails to predict temperature profiles near contact points accurately when typical resolutions are used (20 cells per radius). Our enhancements, utilizing immersed boundary surface values or effective flux, achieve accurate predictions for both conduction and Reynolds numbers from 10 to 200.