In the field of solid–liquid separation, numerous computer simulations have been carried out over the years to improve the understanding of filtration processes. In many cases, coupled CFD–DEM simulations are used to model cake-forming filtration processes [1]. A notable advantage of this approach lies in its ability to account for the complex interactions between the fluid and the particles, among the particles themselves, and between the particles and the filter medium. As the underlying models become increasingly complex and the range of possible adjustable parameters is nearly unlimited, the question arises as to how accurately such CFD–DEM simulations represent the real process.

Consequently, this contribution presents two experimental approaches that facilitate the validation of simulations through experiments. The objective is to establish confidence in the applied models through prior validation, particularly for subsequent simulation studies that cannot be experimentally validated. First, an experimental verification of interference resistance is demonstrated. The interference resistance is defined as the resistance of the first separated particle layers on the filter medium. Although CFD–DEM simulations can resolve interference resistance, it generally cannot be measured experimentally due to unavoidable sedimentation effects [2].

Therefore, an approach was developed to measure interference resistance for the first time using a transparent filter cell (Figure 1a). Since filtration experiments cannot be carried out without the influence of gravity, the possibility of preparing a suspension in which particle sedimentation is prevented by density matching was investigated. Spherical polystyrene beads with a density of 1.05 g/cm³ were used to prepare a suspension based on a water–glycerin mixture. Given the known densities of glycerin (1.26 g/cm³) and water (0.997 g/cm³), the density of the continuous phase of the suspension could be adjusted by varying the mixing ratio of water and glycerin.

The experimentally determined interference resistance (Figure 1b) was then compared with data obtained from CFD–DEM simulations. The second experimental approach presented in this contribution for simulation validation is the comparison of the porosities of real and simulated filter cakes. To determine ...