Towards new contact-less techniques for the control of inertial particles dispersed in a fluid

Lappa, Marcello; (2019) Towards new contact-less techniques for the control of inertial particles dispersed in a fluid. In: 12th International Conference on Thermal Engineering: Theory and Applications, February 23-26, 2019, Gandhinagar , India. ICTEA/Ryerson University, IND.

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Abstract

To achieve success in small-scale manufacturing processes and lab on chip applications new techniques and control principles are necessary. A promising technology to meet these objectives can emerge from improved understanding of induced particle self-organization mechanisms. Controlling the state of aggregation and properties of structures formed by particles immersed in a fluid is a subject of crucial importance at several scales. Practical applications range from the synthesis of advanced alloys to the crystallization of protein substances. Lack of adequate control in these processes is a fundamental methodological and theoretical shortcoming that limits applicability. Here we report on our recent discoveries about the possibility to use thermogravitational, thermocapillary or thermovibrational flows to force dispersed particles, regardless of their nature or type, to self-assemble and produce a variety of highly ordered, reproducible, high resolution structures. We show that the existence of these structures (also known as “attractors”) is due to the delicate interplay of different effects, which involve (but are not limited to) the inertial nature of the particles (i.e. their finite size and mass) and the existence of “waves” travelling in the considered fluid as a result of fluid-dynamic (Hopf) bifurcations or imposed (periodic) forcing. Some effort is also devoted to describe the topology and morphology of these attractors, which range from 1D helical curves to complex 3D surfaces depending on the specific conditions considered.