Article
Water Resources
Pratyaksh Karan, Uddipta Ghosh, Yves Meheust, Tanguy Le Borgne
Summary: Mixing-induced reaction fronts are crucial in subsurface processes and mechanical dispersion leads to faster front propagation and enhanced reaction rate. These findings have broad implications for field conditions at various temporal and spatial scales.
ADVANCES IN WATER RESOURCES
(2023)
Article
Engineering, Aerospace
Dongdong Zhang, Peng Cui, Jianguo Tan, Xiao Yao
Summary: Efficient mixing of fuel and oxidizer is crucial for improving the efficiency of the engine propulsion system. This study proposes the strategy of using a splitter plate cavity to promote mixing in a RBCC combustor. The results show that the splitter plate cavity leads to significant growth of the mixing layer and the newly discovered T-shaped structures play a crucial role in this process.
AEROSPACE SCIENCE AND TECHNOLOGY
(2022)
Article
Physics, Fluids & Plasmas
Jean-Luc Thiffeault
Summary: Fluid mixing involves the interplay between advection and diffusion, and can result in nonuniform mixing under certain conditions. In such cases, characterizing the degree of mixing using an f -divergence or L-1 norm is preferable due to their monotonically decreasing nature, which helps measure the rate of mixing effectively. An example demonstrates that flows that mix well in nonuniform cases can differ significantly from efficiently mixing uniform flows.
PHYSICAL REVIEW FLUIDS
(2021)
Article
Engineering, Aerospace
Byeong-Jo Hwang, Seongki Min
Summary: Efficient mixing and combustion in supersonic flow is critical for developing hypersonic airbreathing propulsion systems, and inducing streamwise vortices is an effective method to enhance and accelerate mixing. Research on mixing enhancement by streamwise vortices has been conducted extensively for decades and has made significant progress.
Article
Mechanics
Sri Savya Tanikella, Emilie Dressaire
Summary: This study investigates the dynamics of fluid-driven fractures in hydraulic fracturing through model experiments. The results show that the growth of fractures is influenced by the competition between viscous, elastic and toughness-related stresses, and the pre-existing fractures have a certain impact on the fracture dynamics.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
S. F. Lewin, C. P. Caulfield
Summary: Motivated by the variation of local shear produced by internal waves in the ocean, this study investigates the effect of a time-dependent shear forcing on the evolution and mixing of turbulence produced by Kelvin-Helmholtz instability (KHI) through direct numerical simulations. The results demonstrate that turbulence produced by KHI with a decelerating shear mixes in a distinctly different way from the flow with constant background shear, with characteristics more in common with convectively driven flows.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mathematics
Masato Tsujii, Zhiyuan Zhang
Summary: We demonstrate that a topologically mixing C infinity Anosov flow on a 3-dimensional compact manifold exhibits exponential mixing with respect to any equilibrium measure with Ho center dot lder potential.
ANNALS OF MATHEMATICS
(2023)
Article
Physics, Multidisciplinary
Saraswat Bhattacharyya, Julia M. Yeomans
Summary: We present an extension of continuum theories of active nematohydrodynamics to investigate the behavior of a two-fluid mixture with separate velocity fields for each component. The interaction between active anchoring and active flows driven by concentration gradients leads to microphase separation in an active nematic fluid mixed with an isotropic fluid. These findings have potential implications for understanding cell sorting processes and the formation of lipid rafts in cell membranes.
PHYSICAL REVIEW LETTERS
(2023)
Article
Mechanics
Seonkyoo Yoon, Marco Dentz, Peter K. Kang
Summary: This study investigates the reactive displacement of two miscible fluids in channel flows and establishes a quantitative link between fluid stretching and chemical reactivity. By changing the Peclet number and systematically varying channel roughness, the relative contributions of stretching and diffusion to mixing-limited reaction are controlled. Optimal ranges of fluid stretching that maximize reactivity are observed, with the competition between enhanced mixing by fluid stretching and reactant mass depletion being the key to optimality.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
W. Herreman, C. Nore, L. Cappanera, J-L Guermond
Summary: This study demonstrates that swirling electrovortex flows can significantly enhance the mixing of alloys in the bottom layer of liquid metal batteries during discharge. By identifying a novel scaling law for the intensity of these flows and using a model developed in a previous study, the minimal intensity of the external magnetic field required for this enhancement is estimated.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Computer Science, Interdisciplinary Applications
Luis F. N. Sa, Carlos M. Jr Jr Okubo, Emilio C. N. Silva
Summary: This work proposes a new topology optimization formulation for subsonic compressible flows, using compressible Navier-Stokes equations coupled with a density-based material model. The algorithm is implemented by a finite element model and evaluated by optimizing 2D domains and a 3D diffuser, resulting in optimized designs with reduced entropy generation.
STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION
(2021)
Article
Mechanics
Hugo N. N. Ulloa, Juvenal A. A. Letelier
Summary: Thermally driven flows in fractures enhance heat transfer and fluid mixing but the energy pathways in such environments have not been characterized. This study introduces novel expressions for energy transfer rates based on two conceptual frameworks and derived energetics using different decomposition methods. The two frameworks lead to the same energy transfer rates at steady state, providing analytical expressions for the energetics and efficiencies of HS-RBC. The impact of thermal forcing and geometrical control on the development of boundary layers and large-scale flows is discussed.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Engineering, Environmental
Ishaan Markale, Gabriele M. Cimmarusti, Melanie M. Britton, Joaquin Jimenez-Martinez
Summary: This study uses MRI to obtain 3D images and investigates the impact of phase saturation on mixing and reactions, explaining the faster than Fickian rate of product formation. The results show that as saturation increases, the product formation also increases.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2021)
Article
Mechanics
Vikash Pandey, Dhrubaditya Mitra, Prasad Perlekar
Summary: A direct numerical simulation study of buoyancy-driven bubbly flows in the presence of large-scale driving that generates turbulence reveals that increasing turbulence intensity leads to more curved bubble trajectories and decreased average rise velocity. The energy spectrum of the flow exhibits pseudo-turbulence scaling for small length scales and Kolmogorov scaling for larger scales. A scale-by-scale energy budget analysis helps understand the scaling behavior seen in the spectrum, with statistical properties consistent with experiments on turbulence modulation by air bubbles in water despite the weak buoyancy of the bubbles.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Qing Wang, Feng Qu, Tianyu Wang, Di Sun, Junqiang Bai
Summary: The mixing of shear layer in a convex wall jet can be suppressed by a highly compressive effect. In this study, spanwise distributed protrusions are used to enhance the mixing. The mixing characteristics and enhancement mechanisms are investigated numerically using the delayed detached-eddy simulation method and the two-equation shear-stress transport model. The results show that the centrifugal effect maintains and amplifies the initial perturbations, resulting in forced streamwise vortices, which significantly increase the growth rate of the jet half-width and shear layer vorticity thickness.
JOURNAL OF FLUID MECHANICS
(2023)
Review
Environmental Sciences
Thomas Sherman, Nicholas B. Engdahl, Giovanni Porta, Diogo Bolster
Summary: Heterogeneity in geologic porous media across different scales leads to non-Fickian or anomalous transport, which traditional models struggle to accurately predict due to constraints in assumptions about independent and identically distributed increments. The Spatial Markov model (SMM), a relatively new model, shows promise in various transport problems in natural porous media and has successfully been used to model complex flows in geology and subsurface hydrology. Further developments and applications of the SMM hold potential for the future.
JOURNAL OF CONTAMINANT HYDROLOGY
(2021)
Article
Water Resources
David A. Benson, Diogo Bolster, Stephen Pankavich, Michael J. Schmidt
Summary: Traditional interpolation techniques for particle tracking involve binning and convolutional formulas using pre-determined kernels. Each particle in the cloud is a sample from the Green's function, and the kernel for interpolation should replicate the cloud itself. An iterative method is proposed to discern the form of the kernel during the process of interpolating the Green's function.
ADVANCES IN WATER RESOURCES
(2021)
Article
Environmental Sciences
Giacomo Medici, Nicholas B. Engdahl, Jeffery B. Langman
Summary: This research proposes an approach to assess vulnerability in bedrock aquifers by combining stable isotope values and particle tracking in three dimensions. The study reveals that deeper aquifer zones have longer particle travel times and distinctive isotopic fingerprints.
INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH
(2021)
Editorial Material
Geosciences, Multidisciplinary
Shannon L. Speir, Lanyu Shang, Diogo Bolster, Jennifer L. Tank, Casey J. Stoffel, Danielle M. Wood, Brett W. Peters, Na Wei, Dong Wang
Article
Engineering, Chemical
Michael J. Schmidt, Nicholas B. Engdahl, David A. Benson, Diogo Bolster
Summary: This research provides formal criteria for choosing the optimal time step length in Lagrangian mass-transfer-based interacting particle methods and validates it through numerical experiments.
TRANSPORT IN POROUS MEDIA
(2023)
Article
Environmental Sciences
Ceara J. Talbot, Diogo Bolster, David Medvigy, Stuart E. Jones
Summary: This study develops a conceptual framework of lateral carbon transport (LCT), focusing on dissolved organic carbon (DOC) transport, and operationalizes it with a coupled terrestrial-aquatic carbon and hydrology model. The research finds that climate is the strongest driver of LCT-DOC, with precipitation positively related and temperature inversely related to LCT-DOC at continental scales. Plant traits, especially water use efficiency, also interact strongly with climate and have a measurable influence on LCT-DOC.
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
(2022)
Article
Water Resources
Nicholas B. Engdahl, Tomas Aquino
Summary: Correlated velocity models have proved useful in describing solute transport behaviors in porous media. This study extends the application of spatial Markov models to time-varying flows and proposes alternative numerical implementations. The validity and efficiency of the models are determined based on standard physical quantities, and clear tests are provided for the applicability of transient, upscaled models.
ADVANCES IN WATER RESOURCES
(2022)
Article
Environmental Sciences
Mariana Alifa, Stefano Castruccio, Diogo Bolster, Mercedes Bravo, Paola Crippa
Summary: This article presents a novel method to reduce uncertainty in health outcome models related to air pollution by increasing input data and quantifying tradeoffs. The method is applied to long-term mortality from fine particulate matter and short-term PM2.5-related mortality in an urban area.
ENVIRONMENTAL RESEARCH
(2022)
Article
Engineering, Civil
Amy Kryston, Marc F. Muller, Gopal Penny, Diogo Bolster, Jennifer L. Tank, M. Shahjahan Mondal
Summary: Climate change affects water allocations in international river treaties. This study presents a method to design climate-robust treaty solutions by considering multiple objectives and uncertainties. The approach is applied to the Ganges water agreement, providing insights for improving transboundary allocations.
JOURNAL OF HYDROLOGY
(2022)
Article
Environmental Sciences
Liming Xing, Diogo Bolster, Haifei Liu, Thomas Sherman, David H. Richter, Kyle Rocha-Brownell, Zhiming Ru
Summary: This study investigates the transport of microplastics in open-channel flows by implementing three Markov models. The models are validated using numerical simulations and laboratory experiments, demonstrating their effectiveness and high efficiency. The research provides new insights into preventing and reducing the environmental hazards of microplastics.
WATER RESOURCES RESEARCH
(2022)
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)
Article
Environmental Sciences
Connor Mullen, Marc F. Mueller, Gopal Penny, Fengwei Hung, Diogo Bolster
Summary: The common-pool nature of groundwater resources leads to over-pumping. In transboundary aquifers, differences in economic and hydrogeologic conditions between users can either dampen or amplify incentives to over-pump. Combinations of different types of user asymmetry can enhance common-pool overdraft.
WATER RESOURCES RESEARCH
(2022)
Article
Geosciences, Multidisciplinary
Lucas Schauer, Michael J. Schmidt, Nicholas B. Engdahl, Stephen D. Pankavich, David A. Benson, Diogo Bolster
Summary: This article presents a parallelized domain decomposition strategy for mass-transfer particle tracking methods. Different tiling techniques for two and three dimensions are investigated and an optimal tiling is determined based on problem parameters and the number of CPU cores. The efficiency of the parallelized algorithms is demonstrated with simulations of a pure diffusion problem.
GEOSCIENTIFIC MODEL DEVELOPMENT
(2023)