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.

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.

Synthesis of Lignin-Based Thermoplastic Copolyester Using Kraft Lignin as a Macromonomer

Binh, N.T.T.,Luong, N.D.,Kim, D.O.,Lee, S.H.,Kim, B.J.,Lee, Y.S.,Nam, J.-D. V.S.P. 2009 Composite interfaces Vol.16 No.7

Beam production of ¹⁸Ne with in-flight method for alpha scattering at CRIB

Duy, N.N.,Chae, K.Y.,Cha, S.M.,Yamaguchi, H.,Abe, K.,Bae, S.H.,Binh, D.N.,Choi, S.H.,Hahn, K.I.,Hayakawa, S.,Hong, B.,Iwasa, N.,Kahl, D.,Khiem, L.H.,Kim, A.,Kim, D.H.,Kim, E.J.,Kim, G.W.,Kim, M.J.,Kwa Elsevier 2018 Nuclear Instruments & Methods in Physics Research. Vol.897 No.-

<P><B>Abstract</B></P> <P>We conducted a measurement of <SUP>18</SUP>Ne + α scattering in inverse kinematics, in order to search for experimental evidence of α -cluster structure in <SUP>22</SUP>Mg above the alpha threshold ( <SUB> E thr </SUB> = 8 . 14 MeV ) and determine the astrophysical rates of the <SUP>18</SUP>Ne( α , p)<SUP>21</SUP>Na reaction under the conditions of break-out from the Hot-CNO cycle. A high intensity <SUP>18</SUP>Ne beam at 2.54 AMeV was successfully produced at CRIB (CNS Radioactive Ion Beam separator) of the Center for Nuclear Study, the University of Tokyo. This paper presents the in-flight production of the radioactive <SUP>18</SUP>Ne beam by using the production reaction <SUP>3</SUP>He(<SUP>16</SUP>O, <SUP>18</SUP>Ne)n with a windowed cryogenic gas target, which was employed in the mentioned resonant α -scattering experiment.</P>

용액공정기반 산화니켈 박막을 이용한 다양한 도체/반도체 소자 제작

Vu Binh Nam,이대호(D. Lee) 한국생산제조학회 2017 한국생산제조시스템학회 학술발표대회 논문집 Vol.2017 No.4

Self-antibacterial chitosan/Aloe barbadensis Miller hydrogels releasing nitrite for biomedical applications

Thai Thanh Hoang Thi,Binh D.T. Trinh,Phuong Le Thi,Dieu Linh Tran,박기동,Dai Hai Nguyen 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.103 No.-

Because of the toxic glutaraldehyde, the chitosan-glutaraldehyde hydrogels are seriously limited inbiomedical applications. In this study, exploiting bioactive compounds of Aloe barbadensis Miller, the chitosan/Aloe barbadensis Miller-glutaraldehyde (CS/AV-GDA) hydrogels were fabricated with 4-fold lowerglutaraldehyde concentration without compromising hydrogel characteristics. The gelation time wascontrolled from a few seconds to several hours. The elastic modulus was varied from 483 to 99940 Pa. The CS/AV-GDA hydrogels could release the natural nitrite amount from 24.0 to 89.6 lM within the firsthour for antibacterial activity, then continuously deliver a few lM every next hour for cell activities. Theantibacterial test against Escherichia coli and Staphylococcus aureus revealed that the CS/AV-GDA hydrogelscould kill the planktonic bacteria 5-fold more highly than control and prevent bacteria attachmenton hydrogel surface effectively. Although the CS/AV-GDA hydrogels consumed only 0.25% glutaraldehydeconcentration, their antibacterial capacities were comparable to chitosan-only hydrogels with 2% glutaraldehyde. For cytotoxicity tests, the CS/AV-GDA hydrogels using 0.25% glutaraldehyde concentrationinduce the human dermal fibroblasts proliferation significantly. All CS/AV-GDA hydrogels with glutaraldehydecrosslinker less than 1% showed non-cytotoxicity. As a result, the new CS/AV-GDA hydrogelsmight become an attractive candidate for medicine regeneration and tissue engineering.

Design, synthesis and biological evaluation of novel hydroxamic acids bearing artemisinin skeleton

Ha, V.T.,Kien, V.T.,Binh, L.H.,Tien, V.D.,My, N.T.T.,Nam, N.H.,Baltas, M.,Hahn, H.,Han, B.W.,Thao, D.T.,Vu, T.K. Academic Press ; Academic Press 2016 Bioorganic chemistry Vol.66 No.-

<P>A series of novel hydroxamic acids bearing artemisinin skeleton was designed and synthesized. Some compounds in this series exhibited moderate inhibition against the whole cell HDAC enzymes. Especially, compound 6g displayed potent cytotoxicity against three human cancer cell lines, including HepG2 (liver cancer), MCF-7 ( breast cancer) and HL-60 (leukemia cancer), with IC50 values of 2.50, 2.62 and 1.28 mu g/mL, respectively. Docking studies performed with two potent compounds 6a and 6g using Autodock Vina showed that both compounds bound to HDAC2 with relatively high binding affinities from -7.1 to 7.0 kcal/mol compared to SAHA (-7.4 kcal/mol). It was found in this research that most of the target compounds seemed to be more cytotoxic toward blood cancer cells (HL-60) than liver (HepG2), and breast (MCF-7) cancer cells. (C) 2016 Elsevier Inc. All rights reserved.</P>

Numerical investigation of dynamic behavior of a compound drop in shear flow

Truong V. Vu,Luyen V. Vu,Binh D. Pham,Quan H. Luu 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.5

We present a numerical investigation of the deformation and breakup of a compound drop in shear flow. The numerical method used in this study is a two-dimensional front-tracking/finite difference technique for representing the interface separating two fluids by connected elements. The compound drop with the initially circular and concentric inner and outer fronts is placed at the center of a domain whose top and bottom boundaries move in the opposite direction. Because of the shear rate, the compound drop deforms and can break up into drops, depending on the flow conditions based on the Reynolds number Re, the Capillary number Ca and the interfacial tension ratio s 21 of the outer to inner interfaces. We vary Re in the range of 0.1-3.16, Ca in the range of 0.05-0.6 and s 21 in the range of 0.8-3.2 to reveal the transition from the non-breakup to breakup regimes. Numerical results indicate that the compound drop breaks up into drops when there's an increase in Re or Ca or a decrease in s 21 beyond the corresponding critical values. We also propose a phase diagram of Ca versus Re that shows the region in which the compound drop changes from the deformation mode to the breakup mode.

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.

Numerical simulation of the freezing process of a water drop attached to a cold plate

Truong V. Vu,Khoa V. Dao,Binh D. Pham 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.5

This paper presents a direct numerical work on the freezing process of a water drop that is either sessile on or pendant from a cold plate. The numerical technique used is an axisymmetric front-tracking method to represent interfaces that separate different phases. The sessile drop corresponds to positive Bond numbers Bo (i.e., Bo > 0), and the pendant drop represents the other values of Bo. Numerical results show that pendant drops break up into liquid drops when gravity dominates the force induced by surface tension at Bo < 0. That is, a decrease in Bo enhances the breakup of the freezing drop. The breakup also depends significantly on the initial shape of the drop in terms of the contact angle at the plate f 0 , that is, increasing f 0 induces breakup. In addition, the drop rapidly completes freezing due to breakup. In the case of non-breakup, the increase in Bo reduces the solidified drop height and decreases the time to complete solidification. The freezing process also consumes minimal time with small f 0 . The solidified drop after solidification has a cone near the axis of symmetry due to volume expansion of water upon solidification. This shape of the solidified drop is in accordance with the experimental observation.