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RISS 인기검색어
- 검색키워드
- 저자 : Hoe D. Nguyen (검색결과 4 건)
- 무료
- 기관 내 무료
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Numerical study of the indentation formation of a compound droplet in a constriction
Hoe D. Nguyen,Truong V. Vu,Phan H. Nguyen,Binh D. Pham,Nang X. Ho,Cuong T. Nguyen,Vinh T. Nguyen 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.4
A compound droplet deforming in a constricted tube widely appears in drug delivery and microfluidic devices. In such a constriction, an indentation can present at the trailing surface of the droplet. However, this aspect has not been fully investigated and understood so far. This study focuses on the effects of some dimensionless parameters on the negative curvature, i.e., indentation, at the trailing surface of a compound droplet moving through a constricted tube. The presence of the constriction at the middle of the tube length enhances the droplet indentation. Numerical results were obtained for the capillary number Ca (varied in range of 0.1 - 1.0), the inner-to-outer droplet radius ratio R 21 (varied in range of 0.2 - 0.9), the droplet-to-tube radius ratio R 10 (varied in range of 0.2 - 0.9), the inner-to-outer interfacial tension coefficient ratio σ 21 (varied in range of 0.1 - 6.4), and the normalized depth of the constriction d/R (varied in range of 0.0 - 0.8). The results reveal that the most influencing factor is Ca, increasing its value leads to the increment of the maximum indentation at the trailing surface of the inner and outer droplets. The indentation is also increased with increasing the value of R 10and d/R. In contrast, increasing R 21 results in a decrease in the indentation at the trailing surface of the outer droplet. When increasing σ 21 , the indentation at the trailing surface of the inner one is quickly suppressed, while the outer droplet is minorly affected. We also point out the patterns of the trailing surface of the inner and outer droplets and their transitions from one to the other patterns in the diagrams based on these parameters.
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Numerical study of collision modes of multi-core compound droplets in simple shear flow
Binh D. Pham,Truong V. Vu,Cuong T. Nguyen,Hoe D. Nguyen,Vinh T. Nguyen 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.5
Collisions of multi-core compound droplets have generated substantial interest in recent years because of their applications in the industry and academia. This study uses the front-tracking method to simulate the transition between the two collision modes of multi-core compound droplets in a simple shear flow. Compound droplets initially assumed identical have two sub-droplets of equal size. Given the shear flow, the droplets collide with one another and behave in two main modes, namely, passing-over and reversing. In the passing-over mode, the droplets pass over one another after coming into contact. The reversing mode appears with two compound droplets returning to their initial sides after the collision. During collision, the subdroplets circulate approximately at the center of their enclosing outer droplets. Some parameters, including capillary number Ca, viscosity ratios μ io and μ mo , radius ratio R io of the subdroplets to the outer droplets, and sub-droplet angle a 0 , are investigated to determine their impact on these modes of collisions. We find that the transition from a reversing to passingover mode occurs when we increase the value of Ca from 0.01 to 0.63, R io from 0.20 to 0.475, and μ io and μ mo in the range of 0.16-6.3. However, an increase in the value of a 0 between −75 oand 90 o leads to a change from a passing-over to reversing mode. Diagrams of the colliding modes are also presented in this research.
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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.
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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.
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