Experimental observation of von Kármán vortices during drop impact

The observation of von Kármán type vortices during the impact of water droplets onto a pool of water is reported. Shadowgraph imaging and laser-sheet visualization are used to document these events. The appearance of these vortices occurs within theoretically predicted regions in a Reynolds-splash number parameter space. In addition, and also in agreement with theoretical predictions, smooth splashing, with vortices absent, is found for smaller Reynolds number. © 2012 American Physical Society.

CFD modeling of single-phase flow in a packed bed with MRI validation

Computational fluid dynamics (CFD) simulations are becoming increasingly widespread with the advent of more powerful computers and more sophisticated software. The aim of these developments is to facilitate more accurate reactor design and optimization methods compared to traditional lumped-parameter models. However, in order for CFD to be a trusted method, it must be validated using experimental data acquired at sufficiently high spatial resolution. This article validates an in-house CFD code by comparison with flow-field data obtained using magnetic resonance imaging (MRI) for a packed bed with a particle-to-column diameter ratio of 2. Flows characterized by inlet Reynolds numbers, based on particle diameter, of 27, 55, 111, and 216 are considered. The code used employs preconditioning to directly solve for pressure in low-velocity flow regimes. Excellent agreement was found between the MRI and CFD data with relative error between the experimentally determined and numerically predicted flow-fields being in the range of 3-9%. © 2012 American Institute of Chemical Engineers (AIChE).

Experimental observation of von Kármán vortices during drop impact.

The observation of von Kármán type vortices during the impact of water droplets onto a pool of water is reported. Shadowgraph imaging and laser-sheet visualization are used to document these events. The appearance of these vortices occurs within theoretically predicted regions in a Reynolds-splash number parameter space. In addition, and also in agreement with theoretical predictions, smooth splashing, with vortices absent, is found for smaller Reynolds number.