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Deformation of a compound droplet in a wavy constricted channel
Hung V. Vu,Truong V. Vu,Binh D. Pham,Hoe D. Nguyen,Vinh T. Nguyen,Hoa T. Phan,Cuong T. Nguyen 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.1
Controlling and adjusting the size and shape of compound droplets is of increasing interest in manufacturing applications using microfluidic channels of complicated geometry. Using numerical simulation in the evolution of computer science with the ability to expand the scope of research and optimize costs is a current research trend. We here provide a numerical simulation analysis of the dynamics of a compound droplet travelling in a circular and sinusoidal-wave tube. The simulations were performed with variations of the Reynolds number, capillary number, droplet size, and channel geometry. It follows that the capillary number strongly impacts the dynamics of the droplet, and the alternation of breakup and finite deformation modes. The deformation increases and the droplet is stretched along the centerline of the channel as the Reynolds number increases. Increasing the length of the wavy region makes the droplet more deformed and enhance its breakup. Regime diagrams based on some of these parameters are also plotted.
A multi-core compound droplet passing through a diffuser channel
Dang T. Bui,Hung V. Vu,Quang D. Nguyen,Truong V. Vu 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.11
This study‘s aim is to improve the understanding of the dynamical behavior of a multi-core compound droplet traveling in an axisymmetric channel consisting of a diffuser element. The compound droplet typically consisting of two inner droplets distributed one after another is initially located at a certain distance from the entrance of the channel. A front-tracking method is used to handle the movement and deformation of the droplet. The numerical simulation results show that the compound droplet is stretched in the channel, and it takes a certain time,“the transit time”, to pass through the diffuser. The compound droplet has the largest deformation in the diffuser region and tends to return to its nearly original shape after leaving the diffuser. The deformation and transit time of the compound droplet are affected by some typical parameters, such as the capillary number and the diffuser angle. For small capillary numbers, the leading inner droplet takes a shorter transit time than the rear one does. The transit time also increases with an increase in the diffuser angle and the number of inner droplets enclosed in the compound droplet.
Thermocapillary migration of a fluid compound droplet
Vinh T. Nguyen,Truong V. Vu,Phan H. Nguyen,Nang X. Ho,Binh D. Pham,Hoe D. Nguyen,Hung V. Vu 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.9
Compound and simple droplets have been studied and appeared in many life applications, e.g., drug processing and microfluidic systems. Many studies have been conducted on the thermocapillary effects on simple droplets, but similar studies on compound droplets are quite rare. Filling this missing gap, this paper presents the front-tracking-based simulation results of the thermocapillary effects on compound droplets in a certain limited domain. The compound droplet consists of a single inner core that is initially concentric with the outer one. Various dimensionless parameters including Reynolds number from 1 to 50, Marangoni number from 1 to 100, droplet radius ratio from 0.3 to 0.8, and viscosity ratios from 0.1 to 6.4 are varied to reveal their influences on the migration of a compound droplet from cold to hot regions. Initially, the inner droplet moves faster than the outer one, and when the leading surface of the inner droplet touches the outer one, the inner and outer droplets migrate at the same speed. The effects of these parameters on the compound droplet eccentricity are also considered.