Article
Environmental Sciences
Lian Zhou, Scott K. Hansen
Summary: We propose a finite volume approach for generating 2D heterogeneous groundwater velocity fields and demonstrate an open-source Python implementation of the method.
WATER RESOURCES RESEARCH
(2022)
Article
Mechanics
Patrice Meunier, Emmanuel Villermaux
Summary: This study analytically solves the advection-diffusion problem of a small surface or line element in three or two dimensions, respectively, using the Ranz transform. The evolution of this element, known as a diffuselet, is numerically computed using the velocity gradient along its trajectory. The concentration profile and statistical properties are obtained, and the results are in good agreement with direct numerical simulations.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Physics, Fluids & Plasmas
Michel Orsi, Lionel Soulhac, Fabio Feraco, Massimo Marro, Duane Rosenberg, Raffaele Marino, Maurizio Boffadossi, Pietro Salizzoni
Summary: Understanding the mechanics of turbulent dispersion is crucial for estimating the effects of mixing processes in various events. Research on passive scalars in turbulent flows focuses on statistics, temporal evolution, and modeling of probability density functions. Direct numerical simulations show that a gamma distribution is a suitable model for passive scalar concentration PDF, aiding in the estimation of mixing timescales for regulating concentration fluctuations.
PHYSICAL REVIEW FLUIDS
(2021)
Article
Astronomy & Astrophysics
Philippe Brax, Anne-Christine Davis, Benjamin Elder
Summary: We derive upper and lower bounds on screened scalar field theories using hydrogenlike systems. Direct coupling between matter and new light scalar fields is heavily constrained by experimental measurements. However, certain theories have screening mechanisms that dynamically weaken this coupling and evade many of these constraints. By computing perturbations to the energy levels of hydrogenlike systems due to screened scalar fields, we find weaker bounds from hydrogen spectroscopy than previously reported. Moreover, we show that muonium experiments are more sensitive probes of screened scalar fields, exploring parameter space that low-energy physics has yet to cover and has only been tested by high-energy particle physics experiments.
Article
Physics, Multidisciplinary
J. Heyman, D. R. Lester, T. Le Borgne
Summary: Steady laminar flows through porous media can lead to Lagrangian chaos at pore scale, impacting a range of transport, reactive, and biological processes. A novel technique based on high-resolution imaging of scalar signatures has been developed to address the challenge of characterizing mixing dynamics in these opaque environments. By estimating the Lyapunov exponent and extending Lagrangian stretching theories, a full characterization of chaotic mixing dynamics in porous materials has been achieved.
PHYSICAL REVIEW LETTERS
(2021)
Article
Mechanics
Alais Hewes, Laurent Mydlarski
Summary: In this study, a novel three-wire thermal-anemometry-based probe is used to investigate the evolution of multiple scalars and velocity in turbulent coaxial jets. The results show that increasing momentum flux ratios lead to complex effects, including the decrease in size of the potential core and the increase in scalar fluctuations. However, the evolution of statistics describing the velocity field is slower. Additionally, the mixing near the beginning of the fully merged region is less effective at higher momentum flux ratios. The study suggests that the mixing process in coaxial jets can be controlled by considering the differences between M<1 and M>1 scenarios.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Physics, Applied
Dionisis Stefanatos, Foteini Avouri, Emmanuel Paspalakis
Summary: This article investigates the use of spatially modulated control fields to increase the efficiency of four-wave mixing in a four-subband semiconductor asymmetric double quantum well. The results show that by using a control field with a constant amplitude and linearly varying mixing angles, near-unity conversion efficiency can be achieved even for short propagation distances.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Geosciences, Multidisciplinary
Yaniv Edery, Martin Stolar, Giovanni Porta, Alberto Guadagnini
Summary: The study reveals that dissolution and precipitation occur in different locations within the system, with preferential flow paths associated with high conductivity values contributing to a sustained feedback between transport and reaction processes. This leads to the emergence of non-Fickian effective transport features over time.
HYDROLOGY AND EARTH SYSTEM SCIENCES
(2021)
Article
Environmental Sciences
Corey D. Wallace, Daniele Tonina, Jeffrey T. McGarr, Felipe P. J. de Barros, Mohamad Reza Soltanian
Summary: The study examines the impact of riparian floodplains on N2O production, finding that N2O production is highest in intermediate-K sediments and emissions increase significantly during storms. Sensitivity analysis reveals that denitrification rate is the most influential factor for N2O flux.
WATER RESOURCES RESEARCH
(2021)
Article
Biochemistry & Molecular Biology
Paul Savary, Jean-Christophe Foltete, Herve Moal, Gilles Vuidel, Stephane Garnier
Summary: In this study, the reliability of cost value inference in connectivity models was assessed under different migration rates, population spatial patterns, and degrees of population size heterogeneity. The study also examined whether considering intra-population variables improved the inference when drift was spatially heterogeneous. The results showed that considering intra-population variables can improve the reliability of cost value inference and better identify the true cost scenarios in certain situations.
MOLECULAR ECOLOGY RESOURCES
(2023)
Article
Engineering, Environmental
Yuqing Zhou, Danny J. Lohan, Feng Zhou, Tsuyoshi Nomura, Ercan M. Dede
Summary: In this paper, an inverse design and dehomogenization framework is proposed to discover innovative microreactor flow field designs. Through numerical simulations, trade-offs between reaction performance and fluid flow performance are found for multiple optimized microreactor flow fields. Applying the findings of this study to new reactor flow field designs can enhance performance in biomedical, pharmaceutical, and energy applications.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Mechanics
R. Boukharfane, A. Er-raiy, M. Elkarii, M. Parsani
Summary: This study systematically investigates the turbulent flow of spatially developing and high-speed hydrogen/air mixing layers subject to small skew angle ζ using direct numerical simulation. The analysis reveals that skewing leads to faster growth of the inlet structures, enhancing mixing in the process. Through transport equations of Reynolds stresses, the underlying mechanisms responsible for turbulence modulation are analyzed.
Article
Physics, Multidisciplinary
Parisa Rahmani, Fernando Peruani, Pawel Romanczuk
Summary: The study reveals that in active systems with topological interactions, spatial heterogeneities can maintain long-range order and enhance the emergence of traveling bands. Topological flocking models in heterogeneous environments exhibit features similar to metric models, with spatial heterogeneities inducing an effective density-order coupling that facilitates the emergence of traveling bands.
COMMUNICATIONS PHYSICS
(2021)
Article
Astronomy & Astrophysics
D. Bazeia, M. A. Liao, M. A. Marques
Summary: We investigate the presence of localized structures for relativistic scalar fields coupled to impurities in arbitrary spatial dimensions. It is shown that the inclusion of explicit coordinate dependence in the Lagrangian does not strongly hinder the existence of stable solutions compared to the impurity-free scenario. We find Bogomol'nyi equations that give rise to global minima of the energy and present some BPS configurations.
Article
Biochemistry & Molecular Biology
Guanghao Li, Zuyu Yang, Dafei Wu, Sixue Liu, Xuening Li, Tao Li, Yawei Li, Liji Liang, Weilong Zou, Chung- Wu, Hurng-Yi Wang, Xuemei Lu
Summary: Spatial genetic and phenotypic diversity within solid tumors can have a significant impact on tumor development. The proposed neutral spatial model suggests that mutation accumulation increases towards the periphery and the genealogical relationships are spatially determined, influencing selection efficacy. Testing this model can provide insights into natural selection during tumorigenesis, particularly for small solid tumors.
MOLECULAR BIOLOGY AND EVOLUTION
(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
Mechanics
Matthias Hinze, Sinan Xiao, Andre Schmidt, Wolfgang Nowak
Summary: This study evaluates and analyzes creep testing results on M2 salt concrete and determines the parameters of the fractional viscoelastic constitutive law using the Bayesian inversion method for reliable prediction of concrete behavior.
MECHANICS OF TIME-DEPENDENT MATERIALS
(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
Computer Science, Interdisciplinary Applications
Ishani Banerjee, Peter Walter, Anneli Guthke, Kevin G. Mumford, Wolfgang Nowak
Summary: Bayesian model selection ranks competing models by computing Bayesian Model Evidence (BME) against test data. Computing BME can be problematic, and we propose a method called the Method of Forced Probabilities (MFP) to address this issue. We demonstrate the effectiveness of our approach on simulating gas migration models.
COMPUTATIONAL GEOSCIENCES
(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
Computer Science, Interdisciplinary Applications
Rebecca Kohlhaas, Ilja Kroeker, Sergey Oladyshkin, Wolfgang Nowak
Summary: Surrogate models are widely used to improve computational efficiency in geophysical simulation problems. Existing multi-resolution PCE is a global representation that cannot estimate the uncertainty of the resulting surrogate. We propose combining multi-resolution PCE and GPE to correct surrogate bias and assess its uncertainty, resulting in a more stable emulator compared to GPE.
COMPUTATIONAL GEOSCIENCES
(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
Environmental Sciences
Sebastian Schwindt, Sergio Callau Medrano, Kilian Mouris, Felix Beckers, Stefan Haun, Wolfgang Nowak, Silke Wieprecht, Sergey Oladyshkin
Summary: This study investigates the use of Bayesian calibration to identify faulty model setups and parameter combinations. Bayesian calibration utilizes a Gaussian process emulator as a surrogate model, which is faster than the actual numerical model. The results show that Bayesian calibration can describe the quality of calibration and correctness of model assumptions through geometric characteristics of posterior distributions.
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)
Editorial Material
Energy & Fuels
Liwei Zhang, Wolfgang Nowak, Sergey Oladyshkin, Yan Wang, Jianchao Cai
Summary: CO2 geological utilization and storage is an effective approach to reduce anthropogenic CO2 emissions. Recent advancements in modeling concepts, experimental approaches, safety assurance, and emerging technologies have driven the development of CO2 geological utilization and storage. A Sino-German joint symposium was organized to encourage global communication and collaboration in this field, bringing together experts from China, Germany, and other countries.
ADVANCES IN GEO-ENERGY RESEARCH
(2023)
Article
Environmental Sciences
Maria Fernanda Morales Oreamuno, Sergey Oladyshkin, Wolfgang Nowak
Summary: Bayesian model selection (BMS) and Bayesian model justifiability analysis (BMJ) provide a statistically rigorous framework for comparing competing models using Bayesian model evidence (BME). However, BME-based analysis has limitations in accounting for a model's predictive performance after calibration and in comparing models using different calibration subsets. To address these limitations, we propose augmenting BMS and BMJ analyses with information-theoretic measures such as expected log-predictive density (ELPD), relative entropy (RE), and information entropy (IE). We demonstrate how these measures, alongside BME, enhance the understanding of the Bayesian updating process and enable objective model comparison using different calibration datasets.
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)
Article
Computer Science, Information Systems
Christoph Dibak, Wolfgang Nowak, Frank Duerr, Kurt Rothermel
Summary: Numerical simulations on mobile devices are important for engineers and decision makers, but providing simulation results is challenging due to complexity and limited resources. This article presents an optimized approach using surrogate models and data assimilation to reduce communication overhead. Evaluation shows that the approach is 6.5 times faster than streaming from the server.
IEEE TRANSACTIONS ON MOBILE COMPUTING
(2023)
