Article
Mechanics
P. W. Agostinelli, B. Rochette, D. Laera, J. Dombard, B. Cuenot, L. Gicquel
Summary: The study proposes a static mesh refinement strategy based on flow physical quantities, detecting areas of interest for flow physics and recommending grid adaptation to enhance the accuracy of large eddy simulations. The strategy is detailed on two reacting-flow problems and shown to significantly improve predictions of flame stabilization.
Article
Environmental Sciences
Hongying Luo, Ran Tao
Summary: The study investigates cavitation behavior using a twisted hydrofoil model at different altitude levels. It finds a relationship between cavitation volume and cavitation coefficient, where high altitude and fewer nuclei result in smaller cavitation size. Additionally, cavitation extends in different directions as the cavitation coefficient decreases.
Article
Construction & Building Technology
Yezhan Li, Wei Wang, Tsubasa Okaze
Summary: The urban heat island effect has become a noticeable issue in recent years. Research has been conducted to understand the thermal field around buildings and improve human comfort in urban areas. However, challenges remain regarding the accuracy and cost of transient simulations of the urban thermal environment.
BUILDING AND ENVIRONMENT
(2023)
Article
Mechanics
Ting-yun Yin, Giorgio Pavesi, Ji Pei, Shou-qi Yuan, Xing-cheng Gan
Summary: This study numerically investigates the unsteady cavitating flow around a trailing-truncated NACA 0009 hydrofoil using large eddy simulation. It identifies two types of cavitation morphologies: cloud cavitation and wake vortex cavitation. The study also discusses the shedding mechanisms of wake vortex cavitation based on finite-time Lyapunov exponent field.
JOURNAL OF HYDRODYNAMICS
(2022)
Article
Mechanics
Yuchang Zhi, Renfang Huang, Rundi Qiu, Yiwei Wang, Chenguang Huang
Summary: This study numerically investigates the unstable vaporous cavities around a surface-piercing hydrofoil. The effects of vaporous cavitation on vorticity generation are found, which is significant for hydrofoil design and flow control.
Article
Engineering, Chemical
Zhenlong Fang, Wenjiang Hou, Zhifan Xu, Xiaofeng Guo, Zenglei Zhang, Ruichao Shi, Yunan Yao, Yong Chen
Summary: High-speed water jets are widely used in deep mining to improve drilling efficiency, and studying the characteristics of these jets is crucial. This study used Three-dimensional Large Eddy Simulation to simulate turbulent flows generated by an organ-pipe nozzle. The results showed the correlation between fluid frequency, inlet pressure, divergence angle, and the occurrence of cavitation.
Article
Thermodynamics
Jiajun He, Qingsong An, Jiangshan Jin, Shuai Feng, Kemu Zhang
Summary: In this study, a visualization experiment and proper orthogonal decomposition (POD) method were used to study the variations in the cavitation shedding frequency and analyze the cavitation flow structure in a 3 mm square nozzle. Large eddy simulation (LES) was performed to explore the causes of cavitation shedding, and the relationship between cavitation and vortices. The re-entrant jet mechanism was found to be the main reason for the shedding of cavitation clouds.
JOURNAL OF THERMAL SCIENCE
(2023)
Article
Mechanics
Tiezhi Sun, Yanyi Ding, Huakun Huang, Bohan Xie, Guiyong Zhang
Summary: The study investigates the effects of modulated ventilation on cavity flows, shedding period, vortex structure, and noise characteristics. Modulated ventilation can change shedding period, improve lift and drag performance, promote hairpin vortices formation, and impose periodicity on vortex structure evolution. Although modulated ventilation enhances pressure fluctuations near the vent and increases self-noise of ventilation, it has little impact on far-field noise while reducing turbulence and total sound pressure level in the wake of the cavitator.
Article
Engineering, Marine
Innyoung Kim, Daegeun Yoon, Jaeyong Jeong, Sunghoon Kim, Donghyun You
Summary: A systematic domain reduction strategy is proposed to mitigate the high computational cost of performing a large-eddy simulation (LES) for predicting underwater radiated noise from a marine propeller. The strategy reduces the LES domain length by up to twice the propeller diameter, representing only 7% of the hull's total length. The effectiveness of the strategy is validated by comparing simulation results with experimental data.
Article
Engineering, Aerospace
Spencer Stebbins, Eric Loth, Andy Broeren, Mark Potapczuk, Christopher Porter
Summary: The study focused on the impact of ice accretion on three-dimensional lifting surfaces, particularly on the aerodynamic performance of the leading edge. The simulations were able to reasonably predict the aerodynamic behavior of the aircraft at high angles of attack, despite the complexity of the flow around the iced swept wing.
JOURNAL OF AIRCRAFT
(2021)
Article
Engineering, Aerospace
Andrey Garbaruk, Michael Strelets, Jeffrey D. Crouch
Summary: Global instability analysis is used to study the effects of extended regions of laminar flow on infinite-span wings. Results show that an extended region of laminar flow leads to a reduction in the critical angle of attack for buffet onset, enhanced growth of all modes of instability, and a higher lift coefficient at buffet onset as compared with fully turbulent conditions. The effects of laminar flow on buffet onset are linked to the suction-side laminar flow and are largely independent of the boundary-layer state on the pressure side of the wing.
Review
Construction & Building Technology
Ferenc Szodrai
Summary: Nowadays, computational fluid dynamics is helping ventilation system designers and architects understand the flow behavior in the indoor environment. Large-eddy simulation is a novel methodology used for these assessments. Adequate discretization of the computational domain and consideration of cell size requirements are key factors for successful simulations.
Article
Thermodynamics
James Slaughter, David Moxey, Spencer Sherwin
Summary: Due to the lack of relevant studies in scientific literature, an open-source geometry was used to analyze the flow physics of a multi-element aerofoil in motorsport. The study provided force data and identified transition mechanisms of each element. The results showed an in-phase relationship at a certain frequency and meandering wake due to instability. These findings will be useful for validating new methods in the field.
FLOW TURBULENCE AND COMBUSTION
(2023)
Article
Computer Science, Interdisciplinary Applications
Jeremy Ims, Z. J. Wang
Summary: We employ a discontinuous high-order method to assess three error indicators aimed at mesh adaptation in large eddy simulation (LES). These indicators are formulated based on specific physical and numerical reasoning. The first indicator is governed by the unsteady residual, the second indicator relies on a local smoothness indicator, and the third one is built upon an estimation for small scale turbulent kinetic energy. We examine the three error indicators by driving autonomous mesh refinement in implicit LES and evaluate their efficacy in reducing solution error by comparing them against direct numerical simulation (DNS) results in two commonly used benchmark simulations of T106 LP turbine cascade.
JOURNAL OF COMPUTATIONAL PHYSICS
(2023)
Article
Mechanics
Shan Gao, Yao Shi, Guang Pan, Xiaobo Quan
Summary: This paper presents refined wake simulations for underwater projectile launch, analyzing the flow fields and vortex structures in the wakes. The results show the presence of a complex vortical system, with the evolution of the vortex being influenced by transverse flow speed and Froude number.
Article
Mechanics
Essam Nabil Ahmed, Alessandro Bottaro
Summary: This study focuses on the fully developed, steady, incompressible, laminar flow in a channel with rough and/or permeable walls. The influence of micro-structured boundary surfaces on the flow behavior is simulated using high-order effective boundary conditions derived from homogenization theory without empirical parameters. A closed-form solution of the Navier-Stokes equations is obtained for the flow in the channel, incorporating slip velocities, shear stress, and streamwise pressure gradient at each virtual boundary. The accuracy and applicability of the model are validated against full feature-resolving simulations for different textures. The Stokes-based model used to identify slip and interface permeability coefficients in the effective boundary conditions is reliable and accurate up to a certain threshold, beyond which advective effects need to be considered.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)
Article
Mechanics
Mustafa Turkyilmazoglu, Faisal Z. Duraihem
Summary: Thermally-driven natural convection in a porous layer is explored theoretically in this work based on Darcy's law. The study focuses on the non-circulating basic cellular flow between two infinitely long horizontal plates and its instability onset. The results show that a circulatory flow and temperature variation along the horizontal axis govern the motion, and the instability can be determined through linear stability analysis and numerical calculations.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)
Article
Mechanics
P. Roca Ramis de Ayreflor, A. Viudez
Summary: In this study, the inelastic interactions between a small, intense dipole and a weak, neutral monopole in two-dimensional flows are examined. It is found that dipoles with small size but large amplitude can cross and scatter off the neutral vortex, while leaving the vortex stable.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)
Article
Mechanics
Nilanjan Mondal, Chirodeep Bakli
Summary: This study presents a micro-nanochannel junction with directional flow achieved by a combination of junction geometry and wall functionalization. The system acts as a fluid diode with asymmetric pressure drop and flow rate in the nanochannel. The directional junction transport can be tuned with slip length, providing a key parameter for engineering various applications. The findings contribute to the understanding of flow rectification systems in nanochannels and have implications for capillary blood flow, desalination systems, and energy storage devices.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)
Article
Mechanics
Ussama Ali, Anas Ghannam, Md Islam, Isam Janajreh
Summary: This study utilizes a passive flow control technique involving a slit through a circular structure to dampen flow-induced vibration. The results demonstrate that the presence of a slit can decrease lift and drag coefficients and suppress flow-induced vibration.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)
Article
Mechanics
Sebastian A. Altmeyer
Summary: This article investigates how an alternating magnetic field can restrict and suppress the generation of vortices in ferrofluidic Couette flow. It finds that when the initially rotating outer cylinder is suddenly stopped, more complex vortex dynamics are generated in the system, and the presence of an alternating magnetic field can modify these dynamics, mainly depending on the modulation amplitude of the field.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)
Article
Mechanics
Pradeep, L. P. Singh
Summary: This study focuses on the analytical solution to the Riemann problem for a 1-D non-ideal flow of dusty gas with external force. The elementary wave curves, including rarefaction wave, shock wave, and contact discontinuity, were obtained and their implications on density, velocity of flow, and shock speed were examined. The addition of external force results in non-self-similar solutions.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)
Article
Mechanics
Meng Fan, Antoine Dazin, Gerard Bois, Francesco Romano
Summary: This study investigates the prominent features of the primary instabilities of a turbulent source flow between finite-span parallel rings with spatially modulated inflow conditions rotating at angular rate n. Two different two-dimensional instabilities that occur at large and low flow rates have been traced back to two different physical mechanisms related to jet-wake and mean-core flow, respectively. The effect of the radial aspect ratios on the instability characteristics of the flow between parallel rings is also considered.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)
Article
Mechanics
Yasmin Hengster, Martin Lellep, Julian Weigel, Matthew Bross, Johannes Bosbach, Daniel Schanz, Andreas Schroder, Florian Huhn, Matteo Novara, Daniel Garaboa Paz, Christian J. Kahler, Moritz Linkmann
Summary: Using curvature and torsion to describe Lagrangian trajectories provides insights into small and large time scales. Probability density functions (PDFs) of curvature and torsion were calculated for experimental Lagrangian trajectories in different flows, and were compared with experimental and numerical simulation results. The effect of anisotropy on geometry or tracer particle trajectories was quantified using the curvature vector, which was found to be related to velocity fluctuations.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)
Article
Mechanics
Nang X. Ho, Truong V. Vu
Summary: The present paper reports numerical results on the solidification process of a hollow drop on an inclined surface. The drop undergoes deformation and forms an asymmetric tip as the surface angle increases. The solidification time, however, is not affected by the surface angle. The fluid accumulates at the bottom of the drop and the bubble moves upwards before being trapped by solidification. A larger bubble reduces the tip shift. The effect of Bond number and Stefan number on solidification is also considered.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)
Article
Mechanics
Idalia Jagodzinska, Bartosz Olszanski, Konrad Gumowski, Slawomir Kubacki
Summary: This study investigates the characteristics of high subsonic and transonic flows through a linear cascade using experimental investigations and numerical simulations. The experiments measured static pressure, flow field, and turbulent intensity, and provided inlet conditions for the numerical simulations. The simulations validated the experimental data and tested the applicability of the turbulence models.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)
Article
Mechanics
Kun Sung Park, Ali Zamiri, Minsuk Choi, Byung Ju Lee, Jin Taek Chung
Summary: In this study, the stator geometry of a single-stage transonic fan was optimized to improve its aerodynamic performance and stall margin. Steady and unsteady simulations were conducted to analyze the impact of shock waves generated by the rotor blade on the stator inlet flow. Using a design of experiment and response surface method, an optimal geometry of the stator blade was obtained to increase the fan's efficiency and stall margin.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)
Article
Mechanics
Yuanzhao Zhang, Bo Li
Summary: This study investigated the effects of longitudinal and lateral spacing on the aerodynamic drag characteristics of the whole team and each member in speed skating team pursuit competition. The results showed that decreasing the longitudinal spacing resulted in greater drag reduction for the whole team and individual skaters. Furthermore, lateral movement of the leading skater also led to additional drag reduction for the team. Computational fluid dynamics simulations revealed differences in drag distribution between the leading skater and the middle and last skaters.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)
Article
Mechanics
Sichang Xu, Chris Peirone, Eugene Ryzer, Gary W. Rankin
Summary: This paper presents a study of a special bistable load-type supersonic fluidic oscillator capable of producing self-sustained oscillations in two gas pressure chambers. The experimental portion verifies the robust nature of the device performance and shows distinct differences compared to a similar prototype. A three-dimensional computational fluid dynamics model is required to accurately simulate the transient filling process, leading to an unaffordable computational cost. To address this issue, a low-order fluid circuit model is developed, which provides an accurate and rapid prediction of the transient performance.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)
Article
Mechanics
Sampson Davis, Eli Shellabarger, James Miller, Thomas Ward
Summary: The present work focuses on studying the effects of shock wave - boundary layer interaction in 2D hypersonic flow at the sharp leading edge of a flat plate and a flat plate followed by a compression ramp. A key parameter, the hypersonic interaction parameter x, is defined and analyzed using a semi-analytic reduced-order model. The study aims to improve on existing methods by characterizing the viscous boundary layer and investigating the upstream influence resulting from the compression ramp.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)