The filling of a container with a free surface jet is an important step in many industries, such as the pharmaceutical or food industries. This process consists in delivering a given quantity of material in the shortest possible time. One of the challenges is to control the flow pattern to avoid overdosing, inclusion of air bubbles or the absence of flatness of the deposit’s free surface. This problem is even more accurate for semi-solid fluids, also known as yield stress fluid or viscoplastic fluids, which generate specific flow forms, particularly in relation to the presence of a yield stress.
In this paper, we propose to identify the different patterns, their characteristics and the effects of process parameters like the average velocity in the injection nozzle, the height between the nozzle and the bottom of the container, called “dosing height”, the nozzle diameter, the average velocity, the injected volume and the container width. These process parameters are the main ways to control industrial processes, since they are adaptable for a given material.
For this purpose, an experimental approach where the injection flows are visualized with a model yields stress fluid. The fluids used allow modulating the rheological properties of semi-solid products, such as yield stress, viscosity and shear-thinning. In addition, the experimental observations are compared to the numerical modelling of these flows by implementing an anelastic Hershel-Bulkley behavior to represent the rheological parameters.
The results show the main effects at work in the conditioning process, such as inertial, viscous, plastic and gravity. The flow patterns as well as the mapping of transitions between them are discussed in terms of the previously mentioned process parameters. The transitions are discussed in terms of the conservation of the mechanical energy of the jet and dimensionless numbers evaluating the ratio of the forces governing the physical phenomenon.
I passed my master’s degree of Research: Fluid Mechanics, in the University of Science and Technology of Lille, France (2019). I was hired by Fromageries Bel SA like Process Engineer. Thanks to several month of experience, I began a PhD in partnership with Fromageries Bel SA and the Laboratoire Rhéologie et Procédés (2020). The topic of the PhD is “Modélisations expérimentale et numérique des écoulements pour le conditionnement des fluids alimentaires”.