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DY: Fachverband Dynamik und Statistische Physik

DY 45: Wetting, Fluidics and Liquids at Interfaces and Surfaces (joint session CPP/DY)

DY 45.1: Talk

Thursday, March 21, 2024, 15:00–15:15, H 0107

Dynamic wetting of concentrated granular suspensions — •Reza Azizmalayeri, Peyman Rostami, and Günter K. Auernhammer — Leibniz-Institut für Polymerforschung, Dresden, Germany

Concentrated granular suspensions are employed in a variety of applications in which the contact line dynamics and internal structure of the suspension interact. The process can be characterized using individual particle analysis and average suspension descriptions. There is a markedly high shear rate at the droplet's contact line. This localized shear rate profoundly affects the suspension's non-Newtonian rheological behaviour. Recent researches have affirmed the applicability of hydrodynamic solutions like Cox-Voinov relation to granular suspensions. Despite these efforts, the impact of particles on the overall flow field and microstructure of densely packed granular systems along the contact line remains unexplored. In this study, a configuration consisting of a pinned droplet on a moving substrate is utilized. Using astigmatism particle tracking velocimetry (APTV), we precisely track the 3D motion of tracer particles within the suspension. Near the advancing contact line, we observe distinct behaviours based on the interaction between particles. A concentrated suspension of low interacting particles violates the Cox-Voinov relationship with particle friction becoming a significant factor. Meanwhile, when strong particle interactions are present the suspension exhibits a yield stress behaviour. The receding contact line exhibits a dynamic curvature that undergoes a transient phase before reaching a stationary state. The results of this study are supported by rheology measurements.

Keywords: Dynamic wetting; Granular suspensions; Rheology