Resonance of droplets in constricted capillary tubes responding to external vibratory excitation can be theoretically characterized by the abstract coefficients such as resonant frequency and rate of damping. A physically sound model, however, is needed to relate these abstract coefficients to the fluid properties of two-phase fluid, geometric properties of tube, and features of excited waves. A hydrodynamic model, based on the moving-boundary control volume concept and the transient oscillatory velocity profile, was developed to characterize the resonance of droplets. This model was validated against computational fluid dynamics simulation results expressed in both time and frequency domains. Dominant factors including Ohnesorge number, viscosity ratio, density ratio, and aspect ratio which control resonance were systematically investigated for their influences on the resonance of droplets. The nonlinearity in light of the initial position of front droplet meniscus and the amplitude of oscillation was distinguished and validated by the theoretical model.


Civil, Architectural and Environmental Engineering

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Article - Journal

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Final Version

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Publication Date

12 Aug 2020