Numerical simulation of filtration processes is used to investigate and improve filtration characteristics especially on the microscale. Coupling of computational fluid dynamics (CFD) with the discrete element method (DEM) is a simulation approach which allows to model all essential microscale effects which occur in solid-liquid filtration processes. The software DNSlab® provides different numerical methods that can be used for such simulations, namely the Lattice Boltzmann Method (LBM) and Finite Differences (FD) methods for the fluid dynamics, coupled with the DEM for the particle modeling.

In previous research [Puderbach, 2021] the LBM was used to describe the filtration behavior of solid spheres in solid-liquid separation processes using 2-way coupling of fluid and particle interactions. The investigations show good agreement of the experimental and numerical results. The 2-way coupling with the LBM allows a very accurate simulation of the particle motion in the fluid, but due to the 2-way coupling it is a very computationally intensive and time-consuming method.

The new 1½-way coupling approach is a further development by omitting too detailed computations which have only a neglectable effect on the filtration characteristic [Schmidt, 2021]. Unlike as for the 2-way coupling, the CFD for the 1½-way coupling doesn’t have to be done by the LBM, the resource-saving FD method can also be used. The approach still allows to simulate the particle deposition and detachment, especially by backwashing the filter cake, but requires significantly less computing resources.

The following figure shows the comparison of simulation and measurement for the separation of glass particles from water at a metal wire mesh [Puderbach2021