Article
Multidisciplinary Sciences
Umberto Ciri, Ruth L. Bennett, Rita Bhui, David S. Molony, Habib Samady, Clark A. Meyer, Heather N. Hayenga, Stefano Leonardi
Summary: This study conducted numerical simulations of coupled hemodynamics and leukocyte transport and adhesion inside coronary arteries, showing good correlation with clinical data. The research revealed that artery geometry, particularly the tortuosity of the centerline, plays a key role in determining the spatial distribution of wall-shear stress and leukocyte adhesion patterns. The findings are encouraging towards establishing a predictive methodology for atherosclerosis progress.
SCIENTIFIC REPORTS
(2021)
Article
Mechanics
Masato Nagata, Baofang Song, Darren P. Wall
Summary: The study reveals the presence of tilted-vortex flow and periodic-vortex flow at the onset of instability in rotating plane Couette flow, challenging the previously established understanding of bifurcations at the transition from laminar to turbulent flow.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Physics, Mathematical
Weizhang Huang, Weishi Liu, Yufei Yu
Summary: Ionic flow is crucial for cell communication, with permanent charge and boundary conditions affecting flow properties. Analytical and numerical studies reveal complex phenomena of permanent charge effects and transitions between small and large charges.
COMMUNICATIONS IN COMPUTATIONAL PHYSICS
(2021)
Article
Mechanics
Sojwal Manoorkar, Jeffrey F. Morris
Summary: Particle motion in pressure-driven suspension flow through a bifurcating channel of square cross-section is studied, with experiments showing deviations in flow behavior compared to pure fluid flow at high solid volume fractions. Vortex formation is suppressed in suspension with an effective viscosity of around 200, indicating strong energy dissipation from particle-wall and particle-particle interactions.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2021)
Article
Thermodynamics
Yu-Jie Chen, Kong Ling, Hao Ding, Yun Wang, Shu-Qi Jin, Wen-Quan Tao
Summary: A three-dimensional conjugated numerical simulation is conducted using the interface capturing method to investigate subcooled flow boiling in a horizontal rectangular mini-channel. The simulation successfully captures hundreds of bubbles with different sizes and reproduces the typical processes and flow boiling patterns. The effects of heat flux and vapor fraction on heat transfer coefficient are discussed, and the heat transfer mechanisms of subcooled flow boiling at different heat flux in the present mini-channel are explored.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Yu-Jie Chen, Kong Ling, Shu-Qi Jin, Wei Lu, Bo Yu, Dongliang Sun, Wei Zhang, Wen-Quan Tao
Summary: In this study, the VOSET method is used to investigate the critical heat flux (CHF) of subcooled flow boiling in a vertical rectangular mini-channel. The relationship between boiling crisis and dry patch is demonstrated, and a new triggering mechanism is proposed. The results show that the appearance of an almost permanent dry patch with high local wall superheating is caused by the continuous coalescence of elongated bubbles midstream and downstream.
APPLIED THERMAL ENGINEERING
(2023)
Article
Mechanics
Yajun Fan, Vladimir Parezanovic, Olivier Cadot
Summary: The paper experimentally investigates the sensitivity of aerodynamic force and body pressure distribution when the flow passes a flat-back, taller than wide Ahmed body in the context of ground vehicle aerodynamics. The study reveals significant non-trivial transitions and sharp base pressure gradients in the parameter spaces, which have important implications for the vehicle's performance. Furthermore, the steady near wake z-instability can be suppressed by using a rear cavity.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Suryadev Pratap Singh, Manojit Ghosh, Meheboob Alam
Summary: Inertial transitions in a suspension Taylor-Couette flow are explored for the first time via experiments. Different vortex states can coexist under different particle loadings, and the particle loading affects the amplitude and wavelength of the vortices as well as the rotation frequency of the spiral vortices.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Gen Wu, Le Fang, Jin Zhang
Summary: This paper introduces a new synthetic turbulence method called AEM and applies it to generate inlet conditions in the open-source software code_saturne. By comparing with direct numerical simulation and synthetic eddy method, the ability of AEM to accurately predict turbulent kinetic energy profiles is validated. Parametric analysis is also conducted to discuss the specific effect of each factor.
Article
Multidisciplinary Sciences
Vikram Rathee, Joia Miller, Daniel L. Blair, Jeffrey S. Urbach
Summary: We directly measured the stress at the boundary of a shear-thickening cornstarch suspension and found persistent regions of high local stress propagating in the flow direction. The structure of these propagating fronts was determined, including the profile of boundary stress and the nonaffine velocity of particles. We also measured the relative flow between the particle phase and the suspending fluid and found it to be highly localized to the fronts and changing direction across the front. These fronts are composed of a localized region of high dilatant pressure and low particle concentration.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Mechanics
J. S. Kern, M. Beneitez, A. Hanifi, D. S. Henningson
Summary: This study investigates the transient and time-asymptotic linear stability of pulsating Poiseuille flow using the optimally time-dependent (OTD) modes framework, revealing that structures akin to Tollmien-Schlichting waves are dominant over a wide range of pulsation frequencies but disappear at low pulsation frequencies. Additionally, the existence of subharmonic perturbation cycles compared to the base flow pulsation is documented for the first time in pulsating Poiseuille flow.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
J. S. Kern, A. Hanifi, D. S. Henningson
Summary: Exceptional points, where eigenvalues and eigenvectors coalesce, lead to resonances and algebraic growth in parallel shear flows. However, the development of non-modal stability theory has reduced interest in spectral degeneracies. The appearance of subharmonic eigenvalue orbits in the periodic spectrum of pulsating Poiseuille flow is related to the coalescence of eigenvalues at exceptional points.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Junbo Lv, Yongming Zhang
Summary: The natural transition of water boundary layers on heated/cooled flat plates is investigated using numerical methods. The influences of wall temperature, oncoming flow velocity, and oncoming flow temperature on the transition are studied. The results show that the heated wall delays transition and produces a fuller velocity profile and a thinner boundary layer for the laminar flow, while a cooled wall advances transition and causes the opposite effects. The oncoming flow temperature has a strong influence on the non-dimensional transition position.
Article
Engineering, Civil
Cristiana Di Cristo, Michele Iervolino, Tommaso Moramarco, Andrea Vacca
Summary: The study investigated the applicability conditions of the Diffusive Wave Model (DWM) for predicting shear-thinning fluid mud-flows, finding that DWM is safe to use in cases of underestimation and acceptable for negative errors less than 5%. The performance of DWM depends on the rheological index of the fluid, and its applicability is determined by the value of the kinematic wave number.
JOURNAL OF HYDROLOGY
(2021)
Article
Mechanics
Yixiang Wang, Kit Ming Lam, Kam Tim Tse
Summary: This study investigates the settling velocity and clustering behavior of bidisperse inertial particles in turbulent channel flow through direct numerical simulation. The results show a significant turbophoresis effect on smaller diameter particles in bidisperse cases, influencing clustering and turbophoresis. It is also found that terminal settling velocities in bidisperse cases are affected by final volume fractions at dynamic equilibrium state, with a strengthened preferential sweeping mechanism observed with decreasing Stokes number.
Article
Mechanics
Mateus C. Guimaraes, Fernando T. Pinho, Carlos B. da Silva
Summary: A new theory is proposed to describe the conformation state of polymer chains in free turbulent shear flows of viscoelastic fluids. The theory shows the existence of minimum and maximum solvent dissipation reduction asymptotes and four different polymer deformation regimes, based on self-similarity arguments and new scaling relations for the turbulent flux of conformation tensor. In addition, analytical solutions for the self-similar transverse profiles of the conformation tensor components are obtained. The theory is validated through excellent agreement with direct numerical simulations employing the FENE-P rheological model.
JOURNAL OF NON-NEWTONIAN FLUID MECHANICS
(2024)
