Immersed boundary method for considering lubrication effects in the CFD-DEM simulations

Although the CFD-DEM simulations could predict the long-range hydrodynamic interaction with high accuracy, they face difficulty in the close distance between particles because mesh resolution is not fine enough to capture the lubrication effects. As a remedy, we used a variant of Immersed Boundary method in our CFD solver to model a problem as a fully resolved simulation. Then, we developed a second-order boundary layer reconstruction approach to increase the accuracy of the immersed boundary method. Furthermore, for the first time and in the present work, we considered how shared cells between the particles need to be treated in the simulation of two approaching particles. Moreover, we investigated the relationship between mesh resolution and time step size on the accuracy of the calculated force. We found a specific range for this ratio to capture the correct short-range hydrodynamic interactions.

Automated summary

Although CFD-DEM simulations can accurately predict long-range hydrodynamic interaction, they face challenges in capturing lubrication effects due to insufficient mesh resolution for close distance particle interactions. To address this, we used a variant of Immersed Boundary method in our CFD solver for fully resolved simulations. We also developed a second-order boundary layer reconstruction approach to improve accuracy. Additionally, we investigated the treatment of shared cells between particles and the impact of mesh resolution and time step size on force calculation accuracy, finding a specific ratio range for correct short-range hydrodynamic interaction capture.