Prediction of Cleaning by Means of Computational Fluid Dynamics: Implication of the Pre‐wetting of a Swellable Soil

The cleaning behavior of a pre-wetted soil is studied experimentally and modeled numerically for the prototypical case of plane channel flow. One of the channel walls is soiled with a food-based model soil containing luminescent tracer particles to perform space- and time-resolved investigations of the cleaning process. Pre-wetting is applied for a few minutes before the soil removal is started with flow of Reynolds number up to 20,000. Physical model and simulation are based on a transient boundary condition to represent the behavior of the soil. Pre-wetting is taken into account by an initial removal of a certain amount of soil due to cohesive separation and the subsequent cleaning modeled as being limited by a diffusive process. Compared to a conventional multiphase simulation, the computation time is lowered by about three orders of magnitude. The results obtained with this elementary approach match the experiments astonishingly well.