Comparison of Drag Force Models in Liquid–Solid Mixed Batch Simulations by Observing Off-Bottom Suspension Flow Patterns

The mixing of liquid–solid systems still poses a challenge in modern engineering. Numerical models often struggle to reliably describe the complex hydrodynamics in many aspects, such as the fundamental drag force model. In this article, an established experimental method is revisited. The method is newly modified through computer-aided image analysis for increased objectivity and repurposed for comparative experiments with numerical results to aid in model validation in practical engineering cases without the need for expensive equipment. The original method consists of measuring patterns forming in settled particles at impeller speeds below the just off-bottom suspension speed in a mixing tank with a flat transparent bottom. The use of mathematical p-norms to fully capture the emerging shapes is introduced here for the first time. Using this methodology, LES CFD results with different drag force models are quantitatively compared with the experimental findings.