Scaling of the bubble formation in a flow-focusing device: Role of the liquid viscosity

Yutao Lu (1) , Taotao Fu (1) , Chunying Zhu (1) , Youguang Ma (1) , Huai-Zhi Li (2)

1 State Key Lab Chem Engn, Sch Chem Engn & Technol, Tianjin
2 LRGP - Laboratoire Réactions et Génie des Procédés

The present work studies the bubble formation in viscous liquids with the viscosity ranging from 5 to 400 mPa s by using a high-speed digital camera. The experiment was carried out in a flow-focusing device with square cross-section of 600×600 μm. Results show that the viscous shear stress strongly influences the dynamics of bubble formation, including the shape and size of bubbles. The bubble size follows power-law relations with the gas flow rate, the flow rate and viscosity of the liquid phase respectively, indicating that bubbles formed in viscous fluids are controlled by a combination of squeezing mechanism and shearing mechanism. Therefore, the bubble size can be predicted by a power-law function depending on the flow rate ratio of gas and liquid phases φ representing the squeezing mechanism and capillary number Ca representing the shearing mechanism. In addition, the dynamics of bubble formation in viscous liquids in a flow-focusing device is also analyzed

Mots clés: Multiphase flow; Interface; Hydrodynamics; Complex fluids; Bubble

Domaines: Génie des procédés; Mécanique des fluides [physics.class-ph]

Yutao Lu, Taotao Fu, Chunying Zhu, Youguang Ma, Huai-Zhi Li. Scaling of the bubble formation in a flow-focusing device: Role of the liquid viscosity. Chemical Engineering Science, 2014, 105, pp.213-219. ⟨10.1016/j.ces.2013.11.017⟩. ⟨hal-02049957⟩