Experimental study of a suspension of non-Brownian particles in an oscillating flow

GARCIA, A. A.; ROHT, Y. L.; HULIN, J. P.; SALIN, D.; GAUTHIER, G.; IPPOLITO, I.

Cordoba

Congreso; II Brazil Argentine Microfluidics Congress V Congreso de Microfluídica Argentina; 2019

We study experimentally the behavior of an isodense suspension of non-Brownian particles in an oscillating flow in a Hele-Shaw cell of gap H.The experiments are carried out with a Newtonian fluid and spherical PMMA particles with a diameter of 40 μm, that have the same refractive index of light. A laser sheet is used to illuminate only a section of the width of the cell for the entire thickness. We work with concentrations of particles (φ) between 20 and 40% in volume and colored between 1 and 3% of the particles using Rhodamine and in this way we were able to visualize them.We use a symmetrical square wave variation of the flow rate, with amplitude q and period T. The oscillating flow was generated from a programmable pump with a high precision syringe.After carrying out the individual tracking of the colored particles, we obtain the velocity profiles of the particles in the thickness of the cell as a function of the flow parameters (q, T) and the different particle concentrations (φ). We find that they do not correspond to the velocity profile of the fluid alone but they present a blunted area in the center of the gap, typical of non-Newtonian fluids.