Article
Thermodynamics
Nikhil Kalkote, Ashwani Assam, Vinayak Eswaran
Summary: This study presents and demonstrates a numerical method for solving chemically reacting flows, extending the single gas density-based framework to handle multi-component gaseous mixtures. The numerical framework has been shown capable of solving non-reacting/reacting laminar and turbulent flow problems, with the SLAU convective scheme for all-speed flows and the k-kl turbulence model for turbulent combustion providing enhanced predictions for industrially important reacting flows.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2021)
Article
Chemistry, Physical
Jonathan H. Frank
Summary: The development of multi-dimensional measurements and imaging techniques in chemical reacting systems provides fundamental insights and progress for understanding complex transport processes and coupling in chemical reactions. Advancements in laser-based imaging diagnostics allow for capturing transient processes and stochastic events, progressing from single-point measurements to multi-dimensional imaging measurements.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Mechanics
Nicolaos Petropoulos, Colm-cille P. Caulfield, Patrice Meunier, Emmanuel Villermaux
Summary: We study the dynamics of dense fluid blob settling, deformation, and mixing in a linearly stratified Taylor-Couette cell. The blob is stretched in the horizontal plane as it settles, forming a lamella that irreversibly mixes with the ambient fluid. The final equilibrium position of the lamella is determined by stretching-enhanced diffusion, and a theoretical mixing model compares favorably with experiments of different Froude numbers.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Ashwini Karmarkar, Jacqueline O'Connor
Summary: The study aims to analyze how increasing free-stream turbulence affects the flow response to longitudinal acoustic excitation. By studying the flow in the wake of a cylindrical bluff body under non-reacting and reacting conditions, we find that varying the level of free-stream turbulence can influence both the amplitude and symmetry of vortex shedding in the presence of longitudinal acoustic excitation.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Mathieu Calero, Holger Grosshans, Miltiadis V. Papalexandris
Summary: In this study, direct numerical simulations (DNS) are conducted to investigate the electrification phenomenon in turbulent channel flow of liquid dielectrics. The results demonstrate that turbulence significantly enhances the transport of electric charge in the bulk of the flow, and the electrification rate increases with the turbulence intensity. Furthermore, the budget analysis of the charge-density variance reveals a balance between molecular transport and turbulent transport. Finally, a closed-form expression for the mean charge-density profile is proposed based on the gradient assumption, which agrees well with the DNS results.
Article
Engineering, Mechanical
Adrian Corrochano, Giuseppe D'Alessio, Alessandro Parente, Soledad Le Clainche
Summary: This work presents a new application of higher order dynamic mode decomposition (HODMD) combined with preprocessing techniques such as principal component analysis (PCA) for the analysis of reactive flows. The new methodology proves to be effective in identifying the main patterns and developing reduced order models. The algorithm is also coupled with feature selection step carried out via PCA and varimax rotation, showing outstanding capabilities in compressing original databases.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
Article
Mechanics
N. Swaminathan, N. Chakraborty
Summary: The dissipation rate of a scalar variance is related to the mean heat release rate in turbulent combustion. For non-premixed combustion, mixture fraction is the key scalar of interest, while a reaction progress variable is relevant for premixed combustion. The analysis shows a dependence on Karlovitz and Damkohler numbers in reactive scalar spectral density in premixed combustion.
Article
Thermodynamics
Friedrich Ulrich, Christian Stemmer
Summary: This study investigates the influence of roughness on the laminar-turbulent transition of hypersonic flows using Direct Numerical Simulations. The study analyzes the interaction between vortical structures and acoustic perturbations, as well as the growth of modal instabilities.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2022)
Article
Energy & Fuels
Joongoo Jeon, Juhyeong Lee, Sung Joong Kim
Summary: In this study, a neural network model based on the finite volume method was developed to accelerate CFD simulations, achieving significantly improved accuracy in multistep time series prediction and faster computational speed compared to traditional methods.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2022)
Article
Thermodynamics
Fredrik Grovdal, Sigurd Sannan, Christoph Meraner, Tian Li, Terese Lovas
Summary: The study discusses a dimensional-decomposition approach for turbulent (reacting) flows by decomposing 3D into 3x1D. The research focuses on the Three-Dimensional Linear Eddy Model (LEM3D) and its recouplings, finding that the auxiliary coupling introduces large gradients leading to increased burning rates. Applications of LEM3D should be limited to areas where high-resolution treatment of scalar mixing and reaction is of particular interest.
FLOW TURBULENCE AND COMBUSTION
(2021)
Article
Computer Science, Interdisciplinary Applications
Brian A. Freno, Brian R. Carnes, V. Gregory Weirs
Summary: The study of hypersonic flows and their underlying aerothermochemical reactions is crucial for the design and analysis of vehicles entering and exiting Earth's atmosphere. Computational physics codes can simulate these phenomena, but verification is essential to ensure their accuracy and credibility. This paper presents code-verification techniques for hypersonic reacting flows in thermochemical nonequilibrium, demonstrating their effectiveness on the Sandia Parallel Aerodynamics and Reentry Code (SPARC).
JOURNAL OF COMPUTATIONAL PHYSICS
(2021)
Article
Mechanics
Roney L. Thompson, Cassio M. Oishi
Summary: This study revisits the concepts of Reynolds and Weissenberg numbers, proposes a method of selecting viscoelastic model parameters with the Oldroyd-B model as a reference, and improves upon the commonly used method in literature. By simulating the behaviors of different viscoelastic models and comparing different methods, it is found that the nonlinearity introduced by the extra parameter was overestimated in the traditional formulation.
JOURNAL OF NON-NEWTONIAN FLUID MECHANICS
(2021)
Article
Engineering, Environmental
Agnieszka Poulain, Alejandro Fernandez-Martinez, Jean-Marc Greneche, Damien Prieur, Andreas C. Scheinost, Nicolas Menguy, Sarah Bureau, Valerie Magnin, Nathaniel Findling, Jakub Drnec, Isaac Martens, Marta Mirolo, Laurent Charlet
Summary: This study investigated the sorption and reduction capacity of synthetic nanomagnetite toward Se(VI). The results showed that under specific conditions, Se(IV) and Fe(II) complexes interacted with magnetite, leading to the reduction and immobilization of Se(VI). Trigonal gray Se(0) and sorbed Se(IV) complexes were observed at pH 5. This study is important for understanding the environmental reactivity of magnetite.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2022)
Article
Mechanics
Ehsan Kian Far, Mohsen Gorakifard, Ehsan Fattahi
Summary: In this paper, a cumulant lattice Boltzmann method is proposed for simulating multiphase-multicomponent flows. The method incorporates an equilibrium distribution function to eliminate the need for external force, resulting in a simplified and computationally efficient approach. Numerical simulations validate the effectiveness and accuracy of the proposed method.
Article
Physics, Fluids & Plasmas
Yohei Kono, Yoshihiko Susuki, Takashi Hikihara
Summary: This study investigates the scale dependence of effective diffusion of fluid tracers and its relation to the Peclet number. A method for characterizing effective diffusivity without relying on scale separation is proposed, and numerical simulations demonstrate the scale dependence of effective diffusivity in specific flow environments.
Article
Biology
Maximilian A. R. Strobl, Andrew L. Krause, Mehdi Damaghi, Robert Gillies, Alexander R. A. Anderson, Philip K. Maini
BULLETIN OF MATHEMATICAL BIOLOGY
(2020)
Article
Multidisciplinary Sciences
Andrew L. Krause, Vaclav Klika, Thomas E. Woolley, Eamonn A. Gaffney
JOURNAL OF THE ROYAL SOCIETY INTERFACE
(2020)
Article
Biology
Yifang Xu, Andrew L. Krause, Robert A. Van Gorder
JOURNAL OF THEORETICAL BIOLOGY
(2020)
Article
Biology
Nick P. Taylor, Hyunyeon Kim, Andrew L. Krause, Robert A. Van Gorder
BULLETIN OF MATHEMATICAL BIOLOGY
(2020)
Article
Biology
Andrew L. Krause, Vaclav Klika, Jacob Halatek, Paul K. Grant, Thomas E. Woolley, Neil Dalchau, Eamonn A. Gaffney
BULLETIN OF MATHEMATICAL BIOLOGY
(2020)
Article
Biology
Robert A. Van Gorder, Vaclav Klika, Andrew L. Krause
Summary: This study investigates pattern-forming instabilities in reaction-diffusion systems on growing or time-dependent domains. By analyzing the structure of linearized perturbations, general conditions for diffusion driven instabilities are obtained, leading to versatile and straightforward differential inequalities as sufficient criteria. The results demonstrate the generality of these conditions across different domain evolution laws and extensions to higher-order spatial systems.
JOURNAL OF MATHEMATICAL BIOLOGY
(2021)
Article
Biology
Thomas E. Woolley, Andrew L. Krause, Eamonn A. Gaffney
Summary: The translation discusses the parameters and processes involved in pattern formation in reaction-diffusion systems.
BULLETIN OF MATHEMATICAL BIOLOGY
(2021)
Article
Biology
Andrew L. Krause, Vaclav Klika, Philip K. Maini, Denis Headon, Eamonn A. Gaffney
Summary: Realistic examples of reaction-diffusion phenomena are rarely isolated systems, with formulations often neglecting the role of domain boundaries. A set of mixed boundary conditions for a two-species reaction-diffusion system is proposed, which forms inhomogeneous solutions away from the boundary of the domain. These boundary conditions can capture a wide range of localized patterning in various dimensions and can be applied to systems involving more than two species, showing a more symmetrical pattern formation and robustness to fluctuations in initial conditions.
BULLETIN OF MATHEMATICAL BIOLOGY
(2021)
Editorial Material
Multidisciplinary Sciences
Andrew L. Krause, Eamonn A. Gaffney, Philip K. Maini, Vaclav Klika
Summary: Elucidating pattern forming processes is a crucial issue in physical, chemical, and biological sciences. Turing's theory on spatial patterns emerging from homogeneous chemical mixtures has been extensively studied mathematically and experimentally for over half a century. Recent research has pushed the boundaries of Turing's original theory to more realistic and complex settings.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2021)
Article
Multidisciplinary Sciences
Andrew L. Krause, Eamonn A. Gaffney, Philip K. Maini, Vaclav Klika
Summary: In the nearly seven decades since the publication of Alan Turing's work on morphogenesis, significant progress has been made in understanding his proposed reaction-diffusion theory. Although Turing's approach has been generalized to various settings, there are still important gaps between theory and experiment, with many remaining challenges to be addressed. Despite advancements in understanding more complex models, obstacles remain in using mathematical techniques to understand biological reality.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2021)
Article
Biology
Alec Sargood, Eamonn A. Gaffney, Andrew L. Krause
Summary: Time delays have significant impacts on the dynamics of pattern formation in reaction-diffusion systems, shrinking the Turing space and increasing the time taken for pattern formation. The distribution kernels have little impact compared to fixed delays with the same mean delay. The location of delay terms in the model can change the size of the Turing space. Time delays have a general impact on reaction-diffusion dynamics, independent of the form of kinetics or location of delayed terms. The effects of delay appear robust under variations of initial and boundary data.
BULLETIN OF MATHEMATICAL BIOLOGY
(2022)
Article
Physics, Multidisciplinary
Joshua S. Ritchie, Andrew L. Krause, Robert A. Van Gorder
Summary: This study explores diffusive instabilities and resulting pattern formation in hyperbolic reaction-diffusion equations, finding that additional temporal terms affect the formation and existence regions of Turing patterns, and are necessary for the emergence of spatiotemporal patterns under wave instability. The parameters leading to wave instabilities are mutually exclusive to those leading to stationary Turing patterns.
Article
Mathematics, Applied
Eamonn A. Gaffney, Andrew L. Krause, Philip K. Maini, Chenyuan Wang
Summary: Motivated by bacterial chemotaxis and multi-species ecological interactions in heterogeneous environments, the study focuses on a one-dimensional reaction-cross-diffusion system with spatial heterogeneity in transport and reaction terms. It is found that a heterogeneous steady state can undergo a Turing-type instability in subsets of the domain, leading to the formation of localized patterns. The study also presents numerical examples of localized pattern formation in different models and shows that the patterns may undergo secondary instabilities resulting in spatiotemporal movement of spikes.
DISCRETE AND CONTINUOUS DYNAMICAL SYSTEMS-SERIES B
(2023)
Article
Biochemistry & Molecular Biology
James D. Glover, Zoe R. Sudderick, Barbara Bo-Ju Shih, Cameron Batho-Samblas, Laura Charlton, Andrew L. Krause, Calum Anderson, Jon Riddell, Adam Balic, Jinxi Li, Vaclav Klika, Thomas E. Woolley, Eamonn A. Gaffney, Andrea Corsinotti, Richard A. Anderson, Luke J. Johnston, Sara J. Brown, Sijia Wang, Yuhang Chen, Michael L. Crichton, Denis J. Headon
Summary: Fingerprints are complex and unique patterns in the skin. The formation of these patterns is still not fully understood, but it is believed to be related to the development of the skin during embryonic stages as well as signaling pathways.
Article
Mathematics, Applied
Robert A. Van Gorder, Alissa Kamilova, Rolf G. Birkeland, Andrew L. Krause
Summary: This study introduces a mathematical model for Soderberg electrodes in metallurgical electrical furnaces, considering heat, mass, and current transfers along with heterogeneous boundary conditions. The research finds that the downward motion of the thermistor strongly influences the position of the baking isotherm, and highlights three key parameters affecting its positioning in industrial applications.
SIAM JOURNAL ON APPLIED MATHEMATICS
(2021)