2019 Volume 75 Issue 2 Pages I_269-I_276
The effects of time increments ∆t and mesh or cell sizes ∆xi are investigated in the computation methods to predict directly the fluid flows among many solid particles, such as some immersed boundary methods and phase-averaged models, in which no empirical formulations, like a permeability k, are needed. First it was pointed out that the fluid-solid interactive term included in the general form of the momentum equation is possibly affected by the time increments ∆t. Then, from the numerical investigations for the flows among solid particles, it was suggested that the reasonable results can be obtained when the diffusion number (ν∆t/∆x2i ) is less than 6.0 × 10−3 and the cell-size resolution against void volume Rs is larger than 5,000.
