Article
Engineering, Mechanical
Thorben Helmers, Philip Kemper, Jorg Thoming, Ulrich Miessner
Summary: This study investigates the change of flow topology in Taylor flow and its relation to excess velocity. Experimental measurements show the momentum transport from the continuous phase to the droplets and how it affects the flow field and the position of the droplet's main vortex core.
EXPERIMENTS IN FLUIDS
(2022)
Article
Mechanics
Zhaokuan Lu, Eric D. Dupuis, Viral K. Patel, Ayyoub M. Momen, Shima Shahab
Summary: Experimental and numerical investigations were conducted to assess the transport behavior of ultrasonic oscillatory air-water two-phase flow in a microchannel, revealing its highly unsteady nature. By conducting parametric studies, key factors affecting flow rate were identified, leading to the determination of the optimal configuration.
Article
Multidisciplinary Sciences
Ranabir Dey, Carola M. Buness, Babak Vajdi Hokmabad, Chenyu Jin, Corinna C. Maass
Summary: Researchers demonstrate the regular, controllable, and reproducible oscillatory rheotaxis in artificial microswimmers. The oscillatory rheotaxis of a self-propelling droplet in a microchannel is primarily governed by shear flow characteristics and the interaction of the finite-sized microswimmer with microchannel walls. These findings provide a realistic understanding of the behavior of active particles in confined microflows, which is relevant in many biotechnology applications.
NATURE COMMUNICATIONS
(2022)
Article
Mathematics, Interdisciplinary Applications
Shuang Yi, Sheng Zheng, Shanshan Yang, Guangrong Zhou
Summary: This paper uses the capillary bundle model to study the flow in porous media and proposes a quantitative model based on fractal geometry to analyze the relationship between hydraulic roughness of capillaries and micro-flow properties. The results show that rough surfaces increase the tortuosity of flow while decreasing the permeability.
FRACTALS-COMPLEX GEOMETRY PATTERNS AND SCALING IN NATURE AND SOCIETY
(2022)
Article
Mechanics
Fahrettin Gokhan Ergin, Erkan Gunaydinoglu, Dilek Funda Kurtulus, Navish Wadhwa
Summary: In this study, the swimming kinematics and flow field characteristics of the zooplankton Acartia tonsa nauplius were investigated using Micro Particle Image Velocimetry (mu PIV). The results showed that A. tonsa has a distinct double peak in its swimming speed profile, and there are a pair of attached vortices in the flow field during the power strokes. The pressure force calculated from the flow fields correlated well with the vertical swimming speed.
FLUID DYNAMICS RESEARCH
(2023)
Article
Thermodynamics
Rituraj Saikia, Pinakeswar Mahanta, Hirakh Jyoti Das
Summary: Experimental investigation on the transient behavior of a PCFB unit during abrupt changes in operating pressure showed that drastic changes in voidage values were observed mostly in the upper region of the riser column for transient conditions in the operating parameters. The experiments demonstrated that heat transfer coefficient momentarily increased with a sudden drop in operating pressure and subsequently decreased steadily, with the reverse observed for a sudden increase in operating pressure.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2021)
Article
Engineering, Manufacturing
Durga Prasad Ghosh, Deepak Sharma, Bahman Abbasi
Summary: The study demonstrates that introducing an adaptive vapor venting strategy can effectively eliminate temperature fluctuations during flow boiling in microchannels, without the need for cooling overdesign, thus improving thermal management efficiency and reliability.
IEEE TRANSACTIONS ON COMPONENTS PACKAGING AND MANUFACTURING TECHNOLOGY
(2021)
Article
Thermodynamics
Wenming Li, Jiaxuan Ma, Chen Li
Summary: The study introduces a new microchannel configuration by combining capillary micro-pinfin fences and multiple micro-nozzles to enhance flow boiling performance, achieving significant improvements in heat transfer on both DI-water and HFE-7100. Especially, a remarkable enhancement in critical heat flux (CHF) has been achieved, showing promising potential for high-power electronics cooling applications.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Mechanics
Olukayode T. Majekodunmi, Sara M. Hashmi
Summary: The study reveals that colloidal clogging behavior varies in different geometric pore structures, with tapered pores showing unique statistical distribution characteristics compared to traditional parallel or series structures. The coexistence of Poisson and lognormal processes in tapered microchannels suggests a complex transient Markov process where clogs can occur independently and dependently on one another. This highlights the importance of considering geometric factors in understanding clogging dynamics.
Article
Biology
Vincent Stin, Ramiro Godoy-Diana, Xavier Bonnet, Anthony Herrel
Summary: We present a method for measuring the 3D vortical structures generated by anguilliform swimmers using volumetric velocimetry. By quantifying the wake of freely swimming dice snakes (Natrix tessellata), we observed the formation of multiple vortices along the snake's body due to its undulation. These vortices typically consisted of paired vortex tubes, with some connected to form a hairpin structure.
JOURNAL OF EXPERIMENTAL BIOLOGY
(2023)
Article
Engineering, Marine
Anping Shu, Matteo Rubinato, Jiping Qin, Jiapin Zhu, Tao Sun, Wei Yang, Mengyao Wang, Ziyue Zhang
Summary: Artificial reefs are effective in improving marine ecological environment and fishery production. Different geometries and spacing configurations can have different effects on hydrodynamics. This study focused on M-Type artificial reefs in Liaodong Bay, China, showing that spacing of 1.25L had the best effects on upwelling and back vortex.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2021)
Article
Energy & Fuels
Jingyu Zhu, Conghui Shan, Keiya Nishida, Wuqiang Long, Dongsheng Dong
Summary: This study examines the two-phase flow characteristics of transient Diesel spray using optical diagnosis techniques and numerical simulation methods, providing insights into the spray structure and turbulent mixing features. Additionally, an improved velocity predicting model accounting for spatial variation is developed for enhanced understanding of the flow dynamics.
Article
Astronomy & Astrophysics
Gabriel S. Rocha, Gabriel S. Denicol
Summary: Matching conditions are crucial in determining the overall consistency properties of relativistic fluid dynamics. This paper derives transient fluid dynamics from kinetic theory without imposing a specific matching condition, and then examines how the choice of matching condition affects the equations of motion and transport coefficients.
Article
Chemistry, Multidisciplinary
Yanpeng Dong, Xingyu Xiang, Zhongdong Wang, Chunying Zhu, Youguang Ma, Taotao Fu
Summary: In this study, the distribution of fluid flow, as well as the uniformity and stability of droplets, in asymmetrical parallelized microchannels were explored using a high-speed camera. The effects of pressure difference fluctuation at the T-junction, hydrodynamic resistance in microchannels, and shear-thinning property of fluids on flow distribution and droplet formation were revealed. The uniformity and stability of droplets in microdevices with different cavity settings were compared, and an optimal configuration was proposed. Prediction models for the flow distribution of shear-thinning fluids in asymmetrical parallelized microchannels were also established.
Article
Multidisciplinary Sciences
Timofey Kozhukhov, Tyler N. Shendruk
Summary: Coarse-grained, mesoscale simulations are essential for studying soft condensed matter. We introduce an algorithm to simulate active nematics, which can model complex systems in an active medium. The method exhibits the key characteristics of active nematic turbulence and active particle models.
Article
Chemistry, Multidisciplinary
Hana Salati, Narinder Singh, Mehrdad Khamooshi, Sara Vahaji, David F. Fletcher, Kiao Inthavong
Summary: This study investigated the dispersion of liquid flow through altered nasal cavities following functional endoscopic sinus surgery (FESS) using Computational Fluid Dynamics (CFD). The results demonstrated the significant impact of postoperative nasal anatomy on the flow dynamics.
PHARMACEUTICAL RESEARCH
(2022)
Article
Physics, Fluids & Plasmas
Xinying Liu, Simon M. Harrison, Paul W. Cleary, David F. Fletcher
Summary: Peristaltic flow plays a crucial role in biological processes such as digestion, making it an important component in stomach simulations. An analytical solution was identified to verify the simulations, providing an equation for net volumetric flow over a cycle with applied sinusoidal wall motion. The smooth particle hydrodynamics (SPH) code and Ansys Fluent Finite Volume Method (FVM) solver demonstrated excellent agreement with the analytic solution and produced similar velocity fields within a range of occlusion ratios. The study also examined parameters influencing solution stability and accuracy. The validation of the SPH model's moving wall capability ensures its reliable use in stomach simulations with wall motion.
Article
Engineering, Chemical
K. Foo, Y. Y. Liang, P. S. Goh, D. F. Fletcher
Summary: This paper reviews the computational parameters and boundary conditions involved in model simulations and discusses the transport mechanisms used for dense and porous gas separation membranes. The impacts of different operation parameters on membrane performance are evaluated, and the effect of obstacles and unsteady flow approaches for improving performance is described. Challenges and future perspectives in CFD simulation involving membrane gas separation are also provided.
CHEMICAL ENGINEERING RESEARCH & DESIGN
(2023)
Article
Engineering, Chemical
Vincent Ngu, David F. Fletcher, John M. Kavanagh, Yan Rafrafi, Claire Dumas, Jerome Morchaina, Arnaud Cockx
Summary: Biological methanation is a promising technology for storing renewable energy, but the scaling-up process faces challenges in H2 gas-liquid mass transfer. This study demonstrates the significant impact of H2 mass transfer on CH4 purity and productivity through analytical, experimental, and numerical approaches. The findings highlight the importance of sparger design in enhancing mass transfer efficiency and improving bioreactor performance.
CHEMICAL ENGINEERING SCIENCE
(2023)
Article
Engineering, Chemical
Y. Y. Liang, D. F. Fletcher
Summary: Forward osmosis (FO) has gained significant research attention for its potential application in seawater desalination. The advancements in FO experimental studies have been accompanied by an increase in computational fluid dynamics (CFD) studies over the past decade. Advanced CFD techniques have allowed for the study of complex flow patterns and the suggestion of solutions to existing problems in FO design and operations. The review of CFD methodology, assumptions, and mathematical models used for FO processes, as well as the discussion on verification and validation, provides insights into the current state of art and challenges in FO CFD studies.
Article
Mechanics
Hana Salati, Patrick Warfield-McAlpine, David F. F. Fletcher, Kiao Inthavong
Summary: Respirators protect against inhalation exposure to dangerous substances, but exhaling accumulates stale air in the mask. Adding a fan to the respirator significantly decreases temperature, humidity, and CO2 concentration inside the mask. Different fan locations have different effects, with the bottom location being the most efficient in removing the nostril jet gas mixture.
Article
Mechanics
Kendra Shrestha, James Van Strien, David F. Fletcher, Kiao Inthavong
Summary: This study used a 3D x-ray scanner to extract the geometry of a nasal spray nozzle and constructed a 3D computational model. A volume-of-fluid to discrete phase transition model was used to track the liquid phase and its transition into droplets based on their shape and size. The computational model was validated through qualitative and quantitative analyses, revealing the early and stable phases of spray plume development. This study provides valuable insights for future nasal spray device designs and techniques for more effective drug delivery.
Article
Mechanics
Jordi Pallares, Alexandre Fabregat, Akim Lavrinenko, Hadifathul Akmal bin Norshamsudin, Gabor Janiga, David F. Fletcher, Kiao Inthavong, Marina Zasimova, Vladimir Ris, Nikolay Ivanov, Robert Castilla, Pedro Javier Gamez-Montero, Gustavo Raush, Hadrien Calmet, Daniel Mira, Jana Wedel, Mitja Strakl, Jure Ravnik, Douglas Fontes, Francisco Jose de Souza, Cristian Marchioli, Salvatore Cito
Summary: This paper discusses the results of the 2022 International Computational Fluid Dynamics Challenge on violent expiratory events and evaluates the ability of different computational codes and turbulence models to reproduce the flow and dispersion of aerosol cloud. 7 research teams from different countries performed 11 numerical simulations using different techniques. The models predicted the shape and range of the buoyant thermal cloud generated by warm exhalation accurately, but underestimated the vertical turbulent mixing and overpredicted the horizontal range covered by the small particle cloud.
Article
Engineering, Chemical
Xinying Liu, Chao Zhong, David F. F. Fletcher, Timothy A. G. Langrish
Summary: In this study, a computational fluid dynamics (CFD) model was used to investigate mass transfer in the dissolution process of tablets in an in vitro beaker and stirrer system. The predicted mass transfer coefficients from the simulation matched well with experimental values. The study also examined the effects of stirrer type and rotation speed on mass transfer.
Article
Biology
S. Schoenborn, T. Lorenz, K. Kuo, D. F. Fletcher, M. A. Woodruff, S. Pirola, M. C. Allenby
Summary: Vascular compliance, both a cause and consequence of cardiovascular disease, is important in the patency of vascular grafts. However, studying the biomechanical effects of localized changes in compliance has been challenging due to limited medical imaging technologies and surgical simulation materials. To address this, a coupled silico-vitro platform was developed to validate numerical fluid-structure interaction results with physical prototypes. The results of this study provide insights into the mechanical behavior of arterial phantoms and have promising applications in studying diseases and optimizing vascular prostheses.
COMPUTERS IN BIOLOGY AND MEDICINE
(2023)
Article
Thermodynamics
F. J. Garcia-Picazo, D. F. Fletcher, G. A. Fimbres-Weihs
Summary: This study investigates the effect of the characteristics of an oscillating flow (i.e., frequency and amplitude) on the occurrence of vortex shedding in membrane channels using CFD simulations. The results show that the resonant frequency for the perpendicular velocity component does not maximize mass transfer, but it significantly increases it. A normalized amplitude of 0.01 appears as a balanced trade-off between mass transfer and pressure drop. The location of onset of vortex shedding moves upstream as the amplitude increases, and mass transfer reaches an upper limit when the onset reaches the first filament.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Engineering, Multidisciplinary
Xinying Liu, Simon M. Harrison, David F. Fletcher, Paul W. Cleary
Summary: This study investigates the buoyancy effects of a mixture of fat and aqueous liquid in the stomach using Smoothed Particle Hydrodynamics (SPH) and Finite Volume Method (FVM). The results show that fat quickly rises to the top layer and liquid sinks to the bottom layer in the curved geometry of the stomach. These buoyancy-driven flow effects occur on a much shorter timescale (6 s) than peristaltic (20 - 60 s) and digestion timescales (hours), and may have implications for understanding digestive processes and guiding food and drug design.
APPLIED MATHEMATICAL MODELLING
(2023)
Article
Computer Science, Interdisciplinary Applications
Xinying Liu, David F. Fletcher
Summary: This paper presents a verification study of wave propagation in fluid-filled elastic tubes using a coupled numerical simulation method by comparing the simulation results with analytical solutions. A three-dimensional fluid-structure interaction numerical model is built using Ansys software. The speed of the pressure wave and the radial displacement of the tube are simulated and compared with theoretical values. Simulation results yield a high level of accuracy. Different structural elements are used to represent the tube, and their impact on the results is discussed. The effects of tube material, tube constraints, and fluid properties are also investigated in this study.
JOURNAL OF ALGORITHMS & COMPUTATIONAL TECHNOLOGY
(2023)
Article
Physics, Fluids & Plasmas
Xinying Liu, Chao Zhong, David F. Fletcher, Timothy A. G. Langrish
Summary: This study designed a new thermoplastic polyurethane (TPU) intestine model and compared it with Fluid Structure Interaction (FSI) simulation. The experimental work provided direct measurement of mixing, while the simulation helped understand the impact of different parameters on the experimental results.
Article
Thermodynamics
Kendra Shrestha, Eugene Wong, Hana Salati, David F. Fletcher, Narinder Singh, Kiao Inthavong
Summary: Increasing irrigation volume and squeeze force improves mucosal irrigation coverage and shear force, enhancing the therapeutic benefit of lavage and distribution of topical medications.
EXPERIMENTAL AND COMPUTATIONAL MULTIPHASE FLOW
(2022)
Article
Thermodynamics
Cong Li, Jiali Wang, Chenhui Wang, Yanke Jin, Yina Yao, Rui Yang
Summary: This study investigates the impact of NaCl water droplets with various concentrations on a heated surface. The results show that the impact patterns can be categorized into different types, and models are established to predict the spreading behavior of droplets with different concentrations. Additionally, high concentration droplets exhibit more violent boiling and have lower residual energy and rebound time.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
C. Barrera, V. Castro, F. Escudero, J. J. Cruz, I. Verdugo, J. Yon, A. Fuentes
Summary: This study focuses on the characterization of soot maturity and sooting propensity of anisole fuel in a controlled laminar coflow diffusion flame. The results show that the spatial distribution of soot volume fraction is enhanced near the flame centerline, while soot production is promoted near the flame wings. The temperature increase also affects the maturity of soot particles.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Roman W. Morse, Jason Chan, Tiago A. Moreira, Jared J. Valois, Evan T. Hurlburt, Jean-Marie Le Corre, Arganthael Berson, Kristofer M. Dressler, Gregory F. Nellis
Summary: This study investigates the dryout of liquid film and the role of disturbance wave frequency. Experimental results indicate that the heat transfer coefficient associated with optimal boiling conditions is maximized when the surface is dry 5% of the time, independent of pulse amplitude and frequency. Liquid-film measurements, dryout statistics, and direct observation suggest that disturbance-wave frequency can be manipulated by density-wave oscillations in the flow field.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
E. J. Vega, J. M. Montanero
Summary: In this study, we experimentally investigated the bursting of a bubble covered with a surfactant. We found that the bubble bursting time is longer compared to a surfactant-free bubble due to interfacial elasticity. Furthermore, the Marangoni stress drives liquid flow that allows the jet to escape from the end-pinching mechanism within a certain surfactant concentration range.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Guofu Sun, Yi Zhan, Tomio Okawa, Mitsuhiro Aoyagi, Akihiro Uchibori, Yasushi Okano
Summary: Experiments were conducted on liquid jets ejected from oval nozzles to investigate the effects of nozzle orifice shape on jet behavior. The study found that the liquid jet exhibited different characteristics at different liquid flow rates. Correlations were established to predict the liquid jet state and characteristics of the secondary droplets produced during jet impact onto a solid surface. This research extended the available knowledge on liquid jet behavior.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Jeonghoon Lee, Laurent Zimmer, Takeshi Saito, Shinji Nakaya, Mitsuhiro Tsue
Summary: This study investigates the effects of spatial resolution on DMD amplitudes and spatial mode strengths, and proposes scaling factors to correct for the resolution differences. The results show that the proposed scaling factors successfully normalize the amplitudes and spatial modes, allowing for quantitative comparison of data obtained with different spatial resolutions. This study is significant for analyzing spatiotemporal data in various fields.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Yanli Zhao, Shibing Kuang, Xiaoliang Zhang, Mingjun Xu
Summary: This study experimentally investigates the dynamic process of water droplet impacting different wood surfaces and analyzes and discusses the impacting phenomena, phenomena distribution, droplet spreading dynamics, and maximum spread factor. The results show that the impacting process can be distinguished by Weber numbers and Reynolds numbers, and can be predicted by mathematical expressions.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Aakhash Sundaresan, Atul Srivastava, Callum Atkinson
Summary: This study presents the first-ever application of an advanced methodology, combining two-color laser-induced phosphorescence and particle image velocimetry, to investigate the heat transfer mechanisms on the surface of a cylinder placed inside a confined square duct. The technique allows for simultaneous measurement of velocity and temperature fields, reducing the complexity and costs associated with separately measuring temperature distributions. Experimental observations show that increasing the mass flow rate enhances heat removal from the cylinder surface, and increasing the cylinder heat input enhances heat transfer in the rear portion of the cylinder.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Harish K. Patel, Sukhjeet Arora, Rutuja Chavan, Bimlesh Kumar
Summary: This study experimentally analyzed the multiscale statistical assessment of scour depth surrounding spur dikes with downward seepage. The research found that seepage affects the morphological behavior and hydrodynamic characteristics of the channel bed, leading to changes in scour formation. The rate of scour depth changes initially increases with higher seepage velocity but eventually becomes constant over time.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Justas Sereika, Paulius Vilkinis, Gediminas Skarbalius, Algis Dziugys, Nerijus Pedisius
Summary: This study experimentally investigated the pulsatile flow structure based on a transitional-type cavity. It was found that the pulsation amplitude has a more significant effect on the dynamics of recirculation zone than the pulsation frequency. Pulsatile flow can reduce the size of the recirculation zone.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Merav Arogeti, Eran Sher, Tali Bar-Kohany
Summary: This study provides a detailed exploration of the events that occur when a droplet hits a dry solid surface of various small sizes, with a focus on the deposition, receding breakup, and prompt splash phases. By utilizing non-dimensional analysis and graphical representation, the boundaries between different events are defined, and criteria for differentiation based on target-to-drop ratio, Reynolds, and Webber numbers are presented.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Tianxiong Li, Fei Wen, Yingchun Wu, Botong Wen, Lei Wang, Jinxin Guo, Xuecheng Wu
Summary: This study investigates the structure of the flow field induced by a strut in a scramjet and its influence on flame stabilization. Experimental and numerical analyses reveal that the flow field exhibits features beneficial for flame stabilization, but the asymmetry of the flow poses a challenge to flame establishment.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Syed Ehtisham Gillani, Yasir M. Al-Abdeli
Summary: This study investigates the asymmetry in bluff-body stabilised annular jets and finds that swirl can significantly mitigate the asymmetry and restore the symmetry of the jets. Moreover, increasing the Reynolds number and the swirl intensity can both decrease the asymmetry of the jets.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Utsav Bhardwaj, Rabindra Kumar, Shyama Prasad Das
Summary: This study presents an experimental investigation on flooding phenomenon in a pulsating heat pipe (PHP) unit cell, and analyzes the impact of flooding on the performance of PHP. The study recognizes three different flooding mechanisms and finds that currently accepted correlations for predicting flooding velocity are inaccurate. The study emphasizes the need for further research on flooding in PHPs.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Yunpeng Xue, Yongling Zhao, Shuo-Jun Mei, Yuan Chao, Jan Carmeliet
Summary: This study investigates the impact of building morphology on local climate, air quality, and urban microclimate. The researchers conducted an experimental investigation in a large-scale water tunnel, analyzing heat and flow fields using Laser-induced Fluorescence (LIF) and Particle Image Velocimetry (PIV). The findings show that factors such as canyon configuration, buoyant force, and approaching flow magnitude significantly influence fluid flow in street canyons, and the morphology of the street canyon dominates ventilation rate and heat flux. For example, changing the aspect ratio of a street canyon can lead to a significant change in air ventilation rate, ranging from 0.02 to 1.5 under the same flow conditions.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
