TY  - JOUR
AU  - Zahoor, Rizwan
AU  - Bajt, Saša
AU  - Šarler, Božidar
TI  - A Numerical Study of Double Flow Focusing Micro-Jets
JO  - International journal of numerical methods for heat & fluid flow
VL  - 35
IS  - 6
SN  - 0961-5539
CY  - Bradford
PB  - MCB Univ. Press
M1  - PUBDB-2024-04885
SP  - 1983 - 2003
PY  - 2024
AB  - Purpose: Double flow focusing nozzles (DFFN) form a coaxial flow of primary liquid with micro-crystalline samples, surrounded by secondary liquid and focusing gas. The paper aims to develop an experimentally validated numerical model and assess the performance of micro-jets from a DFFN as a function of various operating parameters for the water-ethanol-helium system, revealing the jet's stability, diameter, length, and velocity.Design/methodology/approach: The physical model is formulated in the mixture-continuum formulation, which includes coupled mass, momentum, and species transport equations. The model is numerically formulated within the FVM-VOF approach and implemented in OpenFOAM to allow for a non-linear variation of the fluid's material properties as a function of the mixture concentration. The numerical results are compared with the experimental data.Findings: A sensitivity study of jets with Reynolds numbers between 12 and 60, Weber numbers between 4 and 120, and capillary numbers between 0.2 and 2.0 was performed. It was observed that jet diameters and lengths get larger with increased primary and secondary fluid flow rates. Increasing gas flow rates produces thinner, shorter, and faster jets. Previously considered pre-mixed and linear mixing models substantially differ from the accurate representation of the water-ethanol mixing dynamics in DFFNs. We demonstrated that Jouyban-Acree mixing model fits the experimental data much better.Originality: The mixing of primary and secondary liquids in the jet produced by DFFN is numerically modelled for the first time. This study provides novel insights into mixing dynamics in such micro-jets, which can be used to improve the design of DFFN nozzles.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:001336341500001
DO  - DOI:10.1108/HFF-07-2024-0480
UR  - https://bib-pubdb1.desy.de/record/611278
ER  -