Article
Nanoscience & Nanotechnology
Reza Karimi, Sajad Rezazadeh, Mohammad Raad
Summary: This paper presents a three-dimensional study of the nitrogen and oxygen mixing process in a T-type micromixer, and validates the improvement of mixing quality by introducing SAR structures. It is found that at low Reynolds numbers, the mixing quality is high, and increasing the cross-section area of mixing units can enhance mixing quality.
MICROFLUIDICS AND NANOFLUIDICS
(2021)
Article
Engineering, Electrical & Electronic
Guojun Liu, Meng Wang, Luntao Dong, Duanyi Zhu, Conghui Wang, Yanhui Jia, Xinbo Li, Jibo Wang
Summary: A novel Y-shaped split-and-recombine (SAR) micromixer is proposed, which demonstrates better mixing performance and smaller pressure loss due to its three-dimensional structure, splitting recombination, and chaotic convection mechanism. Simulation and experimental results show that the channel aspect ratio has a significant impact on the mixing performance and pressure loss of the micromixer. The micromixer has broad application prospects in chemical synthesis, biochemical analysis, and biomedicine.
SENSORS AND ACTUATORS A-PHYSICAL
(2022)
Article
Computer Science, Interdisciplinary Applications
Shang-Gui Cai, Johan Degrigny, Jean-Francois Boussuge, Pierre Sagaut
Summary: An improved coupling method of immersed boundary method and turbulence wall models on Cartesian grids is proposed to generate smooth wall surface pressure and skin friction at high Reynolds numbers. Various modifications are presented to enhance the near wall solution, and the validity of the method is demonstrated through numerical benchmark tests.
JOURNAL OF COMPUTATIONAL PHYSICS
(2021)
Article
Engineering, Multidisciplinary
Xueying Zhang, Yangjiong Wu
Summary: This paper proposes a high resolution strategy for the localized method of approximate particular solutions (LMAPS). The strategy aims to improve the accuracy and stability of numerical calculation by selecting upwind interpolation templates. Numerical results demonstrate that the proposed high-resolution LMAPS is effective and accurate, especially for solving the Navier-Stokes equations with high Reynolds number.
ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS
(2024)
Article
Mathematics, Applied
Elizabeth Carlson, Adam Larios
Summary: The well-posedness of the formal sensitivity equations with respect to viscosity for the 2D incompressible Navier-Stokes equations is rigorously proven in this study, showing convergence of difference quotients to the unique solution of the sensitivity equations. This proof method provides uniform bounds on difference quotients, indicating stable behavior of parameter recovery algorithms as the system evolves. Additionally, the analysis can be extended to the sensitivity of the 2D Euler equations to viscous regularization, marking a significant development in understanding the global existence and uniqueness of sensitivity equations in fluid dynamics.
JOURNAL OF NONLINEAR SCIENCE
(2021)
Article
Mathematics
Ercan Erturk, Tofigh Allahviranloo
Summary: This paper studies the bifurcations in the solution of the driven semi-elliptical cavity flow, and presents multiple solutions within a specific aspect ratio range. The bifurcation Reynolds numbers for different aspect ratios and multiple solutions at different Reynolds numbers are presented in detail.
Article
Energy & Fuels
Ekta Tripathi, Promod Kumar Patowari, Sukumar Pati
Summary: Numerical simulations in this paper analyze the mixing performance and pressure drop of water and ethyl alcohol in a spiral micromixer for different Reynolds numbers, showing that the spiral micromixer outperforms serpentine and straight micromixers at higher Reynolds numbers. The behavior of mixing index and pressure drop varies for different micromixers at different Reynolds numbers.
CHEMICAL ENGINEERING AND PROCESSING-PROCESS INTENSIFICATION
(2021)
Article
Engineering, Multidisciplinary
S. M. H. Mirkarimi, M. J. Hosseini, Y. Pahamli
Summary: In this study, four curved passive micromixers with different arrangements of cylindrical obstacles alongside with simple curved channel were considered and assessed. The results showed that the special arrangement of the obstacles led to an increase in mixing efficiency at low Reynolds numbers, with Case-B and Case-E performing the best among different configurations.
ALEXANDRIA ENGINEERING JOURNAL
(2023)
Article
Mechanics
Chuong V. Tran, Xinwei Yu, David G. Dritschel
Summary: Incompressible fluid flows are characterized by high correlations between velocity and pressure, as well as between vorticity and pressure. This correlation plays a significant role in maintaining regularity in Navier-Stokes flows. The study suggests that as long as global pressure minimum (or minima) and velocity maximum (or maxima) are mutually exclusive, regularity is likely to persist.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Chemistry, Analytical
Zhenghao Wang, Xingyang Yan, Qizhi Zhou, Qiaoyi Wang, Dongliang Zhao, Hongkai Wu
Summary: We reported a 3D PDMS micromixer based on the splitting-stretching-recombination (SSR) of streams, which can effectively and rapidly mix solutions with low Reynolds numbers. The micromixer is conveniently fabricated using two-photon polymerization (2PP) 3D printing and soft lithography, with high resolution, reproducibility, and ease of integration. It has better performance and higher chip miniaturization compared to other micromixers.
ANALYTICAL CHEMISTRY
(2023)
Article
Mathematics, Applied
Yanqing Wang, Yulin Ye
Summary: In this paper, an energy conservation criterion is derived for weak solutions of both the incompressible and compressible Navier-Stokes equations. The criterion is based on a combination of velocity and its gradient. For the incompressible case, it extends known results on periodic domain, including the famous Lions' energy conservation criterion. For the compressible case, it improves recent results and extends criteria for energy conservation from incompressible to compressible flow.
MATHEMATICAL METHODS IN THE APPLIED SCIENCES
(2023)
Article
Mechanics
Fang Chen, Kun Liu, Ping Li, Lucheng Ji
Summary: This study investigates the non-equilibrium gas flow around a circular cylinder within a range of Knudsen number (Kn) and free-stream Mach number (Ma), using the unstructured grid unified gas kinetic scheme. The impact of Kn and Ma on flow patterns is examined and illustrated through flow pattern diagrams. The results provide insight into the relationship between Reynolds number (Re), Kn, and Ma, and highlight the critical values associated with flow separation, vortex shedding, and shock-wave formation in different flow regimes.
Article
Mechanics
Aditya Saini, Shreyas Narsipur, Ashok Gopalarathnam
Summary: Sensing vortex shedding in unsteady airfoil flows can improve aerodynamic performance, and the time variation of the leading-edge suction parameter can be used to deduce various events related to vortex shedding. The leading-edge flow sensing technique is adapted to deduce the variation of the leading-edge suction parameter during unsteady motion in incompressible flow. By studying the variations of the outputs and calculated parameters, guidelines are presented for detecting vortex shedding events.
Article
Mathematics, Applied
Wenju Zhao
Summary: This article introduces a high order weak Galerkin method for solving Navier-Stokes equations with large Reynolds numbers, demonstrating its efficiency and robustness through numerical testing. Comparisons of different weak Galerkin techniques were performed on benchmark tests such as the Taylor-Green vortex flow, lid-driven flow, and flow around a cylinder.
NUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS
(2022)
Article
Mechanics
Y. Marchenay, F. Chedevergne, M. Olazabal Loume
Summary: A new modeling strategy is proposed to predict the combined effects of roughness and blowing boundary conditions. Analysis of experimental data reveals deficiencies in existing roughness corrections when predicting the effect of blowing in the presence of surface roughness.
Article
Engineering, Chemical
Min-Cheol Park, Sang-Bum Ma, Kwang-Yong Kim
Summary: This study proposes a design and optimization method for a wavy microchannel heat sink, aiming to improve heat transfer and reduce pressure loss by adjusting geometric parameters. Optimization design was conducted using response surface approximation and a multi-objective genetic algorithm, resulting in significant improvements in thermal resistance and friction factor.
Article
Engineering, Aerospace
Tien-Dung Vuong, Kwang-Yong Kim, Cong-Truong Dinh
Summary: This paper investigates a novel casing treatment for an axial compressor that combines a circumferential casing groove with flow recirculation channels. The addition of recirculation channels improved the stall margin while mitigating the penalty in efficiency and pressure rise. Multi-objective optimization successfully improved both objective functions for all representative designs.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
Article
Energy & Fuels
Tien-Dung Vuong, Kwang-Yong Kim
Summary: A casing treatment using inclined oblique slots (INOS) was proposed to enhance the stability of a single-stage transonic axial compressor. Through parametric studies and optimization design, the stall margin was increased by 37.1% with little impact on efficiency and pressure ratio.
Article
Chemistry, Analytical
Toufik Tayeb Naas, Shakhawat Hossain, Muhammad Aslam, Arifur Rahman, A. S. M. Hoque, Kwang-Yong Kim, S. M. Riazul Islam
Summary: A comparative investigation of chaotic flow behavior inside multi-layer crossing channels was conducted in this study to select suitable micromixers. New micromixers were proposed and compared with an efficient passive mixer TLCCM. The results revealed that the new designs exhibited rapid mixing with lower pressure losses compared to the TLCCM configuration.
Editorial Material
Chemistry, Analytical
Kwang-Yong Kim
Review
Energy & Fuels
Muhammad Tanveer, Kwang-Yong Kim
Summary: Membraneless microfluidic fuel cells (MMFCs) are being extensively studied as an alternative to batteries and conventional membrane fuel cells due to their simple functioning and lower manufacturing cost. This review article summarizes different flow configurations of MMFCs reported between 2002 and 2020, focusing on how they improve power density output by reducing or modifying diffusive mixing and depletion zones. Opportunities for research and challenges in improving MMFC performance are also discussed.
Article
Energy & Fuels
Ji-Hyun Oh, Tien-Dung Vuong, Kwang-Yong Kim
Summary: This work conducted a design optimization study to improve the performance of a membraneless microfluidic fuel cell with a double-bridge cross-section of the flow channel. The governing equations were solved numerically to analyze the electrochemical phenomena and evaluate the performance of the fuel cells. Optimization was performed using a genetic algorithm combined with a surrogate model to maximize the peak power density. The optimal design showed a 57.6% increase in peak power density compared to the reference design.
Article
Energy & Fuels
Tien-Dung Vuong, Kwang-Yong Kim
Summary: This study investigated the effects of a dual-bleeding port recirculation channel on the aerodynamic performance of a single-stage transonic axial compressor and optimized its configuration to enhance operating stability. The addition of the bleeding channel increased its stabilizing effect compared to a single-bleeding channel. Optimization resulted in a 51.36% increase in stall margin with only slight reductions in peak adiabatic efficiency and maximum pressure ratio.
Article
Engineering, Mechanical
Nam-Hun Kim, Kwang-Yong Kim
Summary: This study proposes a novel fluidic oscillator shape with a tapered outlet and numerically evaluates its performance parameters. The results show that the tapered outlet improves the overall performance of the fluidic oscillator without a significant increase in pressure drop.
TRANSACTIONS OF THE KOREAN SOCIETY OF MECHANICAL ENGINEERS B
(2022)
Article
Thermodynamics
Hyeon-Seok Shim, Kwang-Yong Kim
Summary: The study investigates the effects of the number of blades on the impeller-volute interaction and flow instability in a centrifugal pump. Numerical simulations and experimental data are used to analyze the fluctuations in performance parameters and local pressure caused by different blade numbers.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART A-JOURNAL OF POWER AND ENERGY
(2022)
Article
Engineering, Mechanical
Ji-Hyun Oh, Tien-Dung Vuong, Kwang-Yong Kim
Summary: In this study, design optimization was performed to improve the performance of a membraneless microfluidic fuel cell. The optimal shape demonstrated a peak power density that was 252% higher than that of the reference shape.
TRANSACTIONS OF THE KOREAN SOCIETY OF MECHANICAL ENGINEERS B
(2022)
Article
Chemistry, Analytical
Naas Toufik Tayeb, Shakhawat Hossain, Abid Hossain Khan, Telha Mostefa, Kwang-Yong Kim
Summary: This study conducted three-dimensional numerical investigations of a novel passive micromixer to analyze the hydrodynamic and thermal behaviors of Nano-Non-Newtonian fluids. The research found that for high nanofluid concentrations, a strong chaotic flow significantly enhances the hydrodynamic and thermal performances at all Reynolds numbers. The proposed micromixer showed comparable mixing energy cost to a recent micromixer in terms of fluid homogenization.
Article
Thermodynamics
Khanh-Duy Cong Do, Duy-Hung Chung, Dang-Quoc Tran, Cong-Truong Dinh, Quang-Hai Nguyen, Kwang-Yong Kim
Summary: Effective cooling structure design is crucial in modern jet engines for improving turbine efficiency and maintaining structural integrity. This study investigates the flow-field and heat transfer characteristics of pin-fin arrays with roughed endwalls, and proposes optimized endwall configurations to enhance heat transfer capacity.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Chemistry, Analytical
Telha Mostefa, Aissaoui Djamel Eddine, Naas Toufik Tayeb, Shakhawat Hossain, Arifur Rahman, Bachiri Mohamed, Kwang-Yong Kim
Summary: In this study, a numerical investigation is conducted to study the unsteady laminar flow of high viscosity fluid in a twisted double planetary mixer. The results show that through the modulation of rotational velocities, chaotic advection can be achieved, enhancing fluid mixing efficiency under low Reynolds and high Peclet numbers.
Editorial Material
Chemistry, Analytical
Kwang-Yong Kim
Article
Engineering, Chemical
Andrea Coletto, Pietro Poesio
Summary: Experiments and simulations were conducted to study the air volume fraction and hold-up in a bubble channel reactor. A new signal processing method was proposed to avoid the loss of bubble residence time. The results were in agreement with previous studies and a bubble-scale model was developed to explain the relationship between hold-up and air superficial velocity.
CHEMICAL ENGINEERING RESEARCH & DESIGN
(2024)
