NUMERICAL PROTOTYPING OF DROPLET GENERATORS

DAVID HARISPE; JORGE CARAM; RAUL URTEAGA; PABLO KLER

Bahía Blanca - Buenos Aires

Congreso; XXXVIII CONGRESO ARGENTINO DE MECÁNICA COMPUTACIONAL; 2022

Asociación Argentina de Mecánica Computacional

Computational mechanics allows the development of numerical prototypes that facilitate theprocess of designing and optimizing devices for microdroplet generation through different virtualexperiments. The formation of microdroplets from one fluid (dispersed phase) into another(continuous phase) can occur in a controlled manner in a discontinuous flow ('dripping'), or acontinuous jet ('jetting') which eventually breaks into droplets far downstream in an uncontrolledmanner. Although experimental systems that are able to produce droplets of up to three phases havebeen reported, the transition from dripping to jetting regime is not yet fully understood even for simpletwo-phase (co-flow) systems. Moreover, the operating conditions (flow ratio, surface tension,geometries) needed for microdroplets to be experimentally produced in two-phase systems are stillunder study. To achieve a model that facilitates the analysis of the conditions involved, resultsavailable in the literature will serve as a starting point while developing a numerical prototype thatcondenses the main characteristics of the co-flow. This will allow us to evaluate and adjust theconditions under which the dripping regime occurs, at a given frequency and droplet size. Thevalidation with experimental results, will allow the evolution of the numerical prototype to a morecomplex version involving the transport of reactive substances for synthesis simulation. For thecomputational model, Basilisk, a free software program for solving flow equations based on thevolume-of-fluid method, is used. Basilisk is designed to perform curvature and surface stresscalculations, efficiently and accurately, for these types of microfluidic applications. The resultsobtained in the computational study of a coaxial system, in the dripping regime, for a two-phase modelare presented and compared with experiments present in the literature.