Article
Mechanics
Danyang Wang, Xiaoyu Luo, Peter S. Stewart
Summary: This paper investigates flow through a channel with a unique structure, demonstrating the possibility of three steady states and analyzing the stability and instability of the system. By adjusting different parameters, the study showcases the varying stability and oscillatory characteristics of the system.
INTERNATIONAL JOURNAL OF APPLIED MECHANICS
(2021)
Article
Mathematics, Applied
Francesca Bernardi, Shankararaman Chellam, N. G. Cogan, M. N. J. Moore
Summary: We obtained a class of exact solutions for Stokes flow in infinite and semi-infinite channel geometries with permeable walls. These series expressions for pressure and Stokes flow are simple, explicit, and valid for all permeability values. The study is motivated by the need to quantitatively understand the detailed fluid dynamics applicable in various engineering applications.
STUDIES IN APPLIED MATHEMATICS
(2023)
Article
Chemistry, Physical
Le Song, Mahmud Kamal Raihan, Liandong Yu, Sen Wu, Nayoung Kim, Savannah Rose Till, Yongxin Song, Xiangchun Xuan
Summary: The merging flow in a T-junction is influenced by fluid shear thinning and elasticity. Depending on the strength of these two properties, the flow near the stagnation point can either be vortex dominated or have unsteady streamlines. Shear thinning induces a symmetric unsteady flow, while viscoelastic fluids exhibit asymmetric unsteady flow with greater interfacial fluctuations.
Article
Mechanics
Filipe R. Amaral, Andre V. G. Cavalieri, Eduardo Martini, Peter Jordan, Aaron Towne
Summary: A resolvent-based methodology is used to estimate velocity and pressure fluctuations in turbulent channel flows, with optimal results achieved when true forcing statistics are utilized. Comparisons with approximate forcing models show the significant benefit of using true forcing statistics in accurately estimating flow structures.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Q. Luo, G. Dolcetti, T. Stoesser, S. Tait
Summary: The water surface response to turbulent flow over a backward-facing step is investigated using high-resolution large-eddy simulation (LES). The LES method is validated using experimental data and the analysis reveals the interplay between turbulence structures and the dynamics of the water surface. The water surface deformation is mainly influenced by gravity waves and turbulence-driven forced waves. The study highlights the importance of decomposing water surface fluctuations to understand the underlying flow structure dynamics.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Omer M. M. Babiker, Ivar Bjerkebaek, Anqing Xuan, Lian Shen, Simen A. Ellingsen
Summary: Through the study of direct numerical simulation (DNS) data, it is found that the imprints of surface-attached vortices can be effectively distinguished from other turbulent surface features based on their circular shape and longer persistence. A computer vision procedure is developed to detect and track vortices solely based on their surface features, with a sensitivity and accuracy of 90% or better. The relationship between the number of surface dimples and the mean-square surface divergence suggests that visible free-surface dimples can be used as a proxy to remotely estimate the rate of mass flux across the surface in some natural flows.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Giorgos Kanellopoulos, Dimitrios Razis, Ko van der Weele
Summary: This paper theoretically describes the appearance and characteristics of granular roll waves in chute flow, as well as the maximal size these waves can attain for a given influx of material. The paper finds that the size of the roll waves is constrained by a homoclinic loop in phase space, and larger amplitude roll waves can be generated by increasing the Froude number.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Giorgos Kanellopoulos
Summary: This paper focuses on the mathematical interpretation of the theoretical existence of the granular monoclinal wave, categorizing it into two classes based on the form of the waveform. The critical Froude number for stable uniform flows is determined from the stability analysis of the dynamical system.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Multidisciplinary Sciences
Linus Engelmann, Josef Hasslberger, Seung-Jin Baik, Markus Klein, Andreas Kempf
Summary: A new benchmark case is presented in this study to evaluate models and methods for direct numerical simulation (DNS) and large-eddy simulation (LES). The Taylor-Green vortex is modified by adding walls and a passive scalar to mimic heat transfer. The case provides clean boundary and initial conditions, making it suitable for assessing LES modeling strategies. The results show that the proposed case features challenging flow dynamics not covered by the default Taylor-Green vortex, justifying its usefulness as a benchmark.
SCIENTIFIC REPORTS
(2023)
Article
Chemistry, Physical
Meng Yue, Jingwang Yan, Huamin Zhang, Qiong Zheng, Xianfeng Li
Summary: The study suggests that flow channel design can improve the performance of trapezoid flow batteries by reducing polarization and capacity loss. Furthermore, the impact of parameters such as channel depth and electrode porosity on flow patterns is discussed, highlighting the importance of further geometrical optimization.
JOURNAL OF POWER SOURCES
(2021)
Article
Chemistry, Multidisciplinary
Asla A. AL-Zahrani, Adnan, Ishtiaque Mahmood, Khaleeq Ur Rahman, Mutasem Bani-Fwaz, Elsayed Tag-Eldin
Summary: This study aims to conduct research on a new biohybrid nanofluid model (BHNFM) in permeable media, with the addition of quadratic radiation, resistive heating, and magnetic field effects. By varying the wall contraction number and increasing the magnetic effects, desired fluid movement and control can be achieved. The findings of this study can contribute to a better understanding of parametric predictions and heat transfer in biohybrid nanofluids.
Article
Mechanics
S. Blanchard, N. Odier, L. Gicquel, B. Cuenot, F. Nicoud
Summary: In the framework of wall-modeled large-eddy simulation (WMLES), the static Smagorinsky model predicts efficiently the wall shear stress, while more advanced static models like WALE or Sigma fail in this aspect. Smagorinsky is known to be too dissipative in the bulk flow and purely sheared flows, whereas the other models are better suited for near-wall flows.
Article
Mechanics
Kiran Jadhav, Abhilash J. Chandy
Summary: Large eddy simulations are performed for high-magnetic Reynolds number inhomogeneous magnetohydrodynamic flows. The simulations are validated using benchmark channel flow results and utilize a hybrid formulation of spectral and finite difference methods. The effect of velocity shear on magnetic field structures is explored for different interaction parameters. It is observed that for higher interaction parameters, the transition from laminar to turbulent is inhibited, while for lower values, a turbulent state is observed. The final state for the lower interaction parameter is characterized by a homogeneous distribution of large and small scales.
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
Engineering, Chemical
Philippe Gouze, Alexandre Puyguiraud, Delphine Roubinet, Marco Dentz
Summary: This study investigates the pore-scale transport of a passive solute in three types of reservoir rocks with different heterogeneity characteristics. Two numerical modeling methods are used to compare the impact of pore-scale flow velocity distribution on large-scale transport behavior. Results show that the presence of numerical dispersion does not significantly affect the simulated large-scale transport compared to the impact of velocity fluctuations.
TRANSPORT IN POROUS MEDIA
(2023)
Article
Engineering, Chemical
Lazaro J. Perez, Alexandre Puyguiraud, Juan J. Hidalgo, Joaquin Jimenez-Martinez, Rishi Parashar, Marco Dentz
Summary: We study mixing-controlled chemical reactions in unsaturated porous media from a pore-scale perspective. The results show that there is a significant increase in reactive mixing for decreasing saturation, which is caused by the stronger heterogeneity of the water phase and flow field.
TRANSPORT IN POROUS MEDIA
(2023)
Article
Engineering, Chemical
Alessandra Bonazzi, Marco Dentz, Felipe P. J. de Barros
Summary: In this study, we investigate transport of an inert solute in multidimensional porous media and analyze the factors that impact solute mixing. We compare the probability distributions obtained from numerical simulations with the beta distribution and propose variable transformations to improve the fit at low concentrations. The results are validated against existing analytical solution for both homogeneous and heterogeneous media.
TRANSPORT IN POROUS MEDIA
(2023)
Article
Engineering, Chemical
Marco Dentz, Juan J. Hidalgo, Daniel Lester
Summary: This review provides an overview of concepts and approaches for quantifying passive, non-reactive solute mixing in porous media flows. It discusses the interrelated processes of stirring, dispersion, and mixing, and reviews different methods to quantify them. The review also emphasizes the multiscale nature of mixing and its dependence on medium structure and flow conditions.
TRANSPORT IN POROUS MEDIA
(2023)
Article
Biochemistry & Molecular Biology
Pedro F. P. Brandao-Dias, Daniel M. C. Hallack, Elise D. D. Snyder, Jennifer L. L. Tank, Diogo Bolster, Sabrina Volponi, Arial J. J. Shogren, Gary A. A. Lamberti, Kyle Bibby, Scott P. P. Egan
Summary: Environmental DNA (eDNA) analysis is a powerful tool for detecting target organisms remotely. This study explores the possibility of obtaining longitudinal dynamics information on targets by separating different size components of eDNA within a sample. The results show that medium-sized particles decay more slowly and increase in proportion over time. Different sizes of eDNA particles do not decay independently, but a parsimonious mathematical model best explains the data. A framework for discerning target distance and abundance with eDNA data is proposed.
MOLECULAR ECOLOGY RESOURCES
(2023)
Editorial Material
Engineering, Chemical
Marco Dentz, Daniel R. Lester, Michel F. M. Speetjens
TRANSPORT IN POROUS MEDIA
(2023)
Article
Environmental Sciences
Ilan Ben-Noah, J. J. Hidalgo, Joaquin Jimenez-Martinez, Marco Dentz
Summary: In this study, the upscaling of pore-scale solute transport in partially saturated porous media at different saturation degrees was investigated. It was found that the interaction between structural heterogeneity, phases distribution, and small-scale flow dynamics leads to complex flow patterns and broad probability distributions of flow. A continuous-time random walk (CTRW) framework was used to upscale and evaluate the transport of diluted solutes, and the results were compared to direct numerical simulations. The analysis showed that the fluid phase saturation, as well as the Peclet number, influenced the advective tortuosity, characteristic length, fraction of immobile region, mean trapping time, trapping length, and trapping frequency.
WATER RESOURCES RESEARCH
(2023)
Article
Environmental Sciences
Marie-Madeleine Stettler, Marco Dentz, Olaf A. A. Cirpka
Summary: Macrodispersion in heterogeneous formations is caused by spatial variability of the velocity field. Differential advection interacts with diffusion to determine effective dispersion, while pure advection is reversible and diffusion is irreversible. We found that the reversibility of macrodispersion is bigger for ensemble dispersion than for effective dispersion, challenging the use of the latter as a metric of mixing.
WATER RESOURCES RESEARCH
(2023)
Article
Water Resources
Laurent Talon, Emma Ollivier-Triquet, Marco Dentz, Daniela Bauer
Summary: Transport processes in the subsurface are strongly influenced by the heterogeneity of the porous structure. The heterogeneity of the permeability field and exchange times have significant impacts on the transient and asymptotic transport regimes. A parametric study is conducted to investigate these impacts and a continuous time random walk (CTRW) model is developed to upscale the transport behaviors.
ADVANCES IN WATER RESOURCES
(2023)
Article
Environmental Sciences
Daniel R. Lester, Marco Dentz, Prajwal Singh, Aditya Bandopadhyay
Summary: This study compares the transverse macrodispersion in porous media with different conductivity structures under purely advective transport. It is found that porous media with smooth, locally isotropic hydraulic conductivity exhibit zero transverse macrodispersion, while non-smooth or locally anisotropic conductivity fields can generate transverse macrodispersion. These findings provide insights into the mechanisms that govern transverse macrodispersion in groundwater flow.
WATER RESOURCES RESEARCH
(2023)
Article
Physics, Fluids & Plasmas
A. Ganesh, C. Douarche, M. Dentz, H. Auradou
Summary: This paper presents a numerical study on the dispersion of bacteria in a plane Poiseuille flow, modeling the bacteria as active Brownian ellipsoids. The longitudinal and transverse macroscopic dispersion coefficients are determined and their scaling with the Peclet number is studied. Three different regimes are observed: a Taylor dispersion regime at low shear rate, an intermediate active regime with increased longitudinal dispersion and decreased transverse dispersion, and a new Taylor regime with diffusivity determined by molecular diffusion coefficient. The active regime is shown to originate from the increased time taken by particles to diffuse across the channel gap, and the transition to the active regime is delayed by decreasing the channel height.
PHYSICAL REVIEW FLUIDS
(2023)
Article
Geosciences, Multidisciplinary
Marco Dentz, James W. Kirchner, Erwin Zehe, Brian Berkowitz
Summary: In this study, we investigate anomalous transport in a hydrological catchment system over a 36-year period at kilometer scales. Using spectral analysis, we examine the fluctuation scaling of long-term time series measurements of chloride, a natural passive tracer, for rainfall and runoff. The findings suggest that the scaling behavior can be described by a continuous time random walk (CTRW) based on a power-law distribution of transition times, indicating the presence of two distinct power-law regimes in the overall travel time distribution in the catchment. The CTRW framework provides a means to assess anomalous transport in catchments and its implications for water quality fluctuations.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geosciences, Multidisciplinary
Ran Holtzman, Marco Dentz, Ramon Planet, Jordi Ortin
Summary: We develop a thermodynamic framework for quasistatic dissipative systems with multiple metastable states by utilizing the return-point memory of cyclic macroscopic trajectories. Using this framework, we analyze and quantify the energy dissipation during quasistatic fluid-fluid displacements in disordered media. Numerical computations reveal that energy dissipation in quasistatic displacements is primarily caused by abrupt changes in the fluid-fluid configuration between consecutive metastable states (Haines jumps), which depend on microstructure and gravity. Comparison with quasistatic experiments helps determine the relative importance of viscous dissipation.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Environmental Sciences
Satoshi Izumoto, Joris Heyman, Johan Alexander Huisman, Kevin De Vriendt, Cyprien Soulaine, Francesco Gomez, Herve Tabuteau, Yves Meheust, Tanguy Le Borgne
Summary: Mixing fronts at the interface of opposing flows are compressed at a constant rate, leading to enhanced chemical gradients and biogeochemical processes. This study investigates how fluid compression controls the amplitude of mixing and reaction rates in porous media. The experimental and numerical results provide new insights into the dynamics of mixing-induced reactions in porous media.
WATER RESOURCES RESEARCH
(2023)
Article
Environmental Sciences
Aronne Dell'Oca, Marco Dentz
Summary: In this study, we focus on the upscaling and prediction of ensemble dispersion in two-dimensional heterogeneous porous media, specifically transverse dispersion. We investigate the stochastic dynamics of advective particles in the heterogeneous flow field and find that transverse dispersion exhibits ultraslow diffusion due to the solenoidal character of the flow field. By analyzing particle velocities and orientations through equidistant sampling along particle trajectories obtained from direct numerical simulations, we derive a stochastic model that combines correlated Gaussian noise for transverse motion and a spatial Markov model for particle speeds. We compare the model results with detailed numerical simulations in different heterogeneous porous media.
WATER RESOURCES RESEARCH
(2023)
