scholarly journals Transport phenomena in complex systems (part 1)

2021 ◽  
Vol 379 (2205) ◽  
pp. 20200301
Author(s):  
Dmitri V. Alexandrov ◽  
Andrey Yu Zubarev
Keyword(s):  
Complex Systems ◽  
Blood Vessels ◽  
Transport Phenomena ◽  
Experimental Studies ◽  
Computational Modelling ◽  
Biological Tissues ◽  
Transport Processes ◽  
Nonlinear Transport ◽  
The Impact

The issue, in two parts, is devoted to theoretical, computational and experimental studies of transport phenomena in various complex systems (in porous and composite media; systems with physical and chemical reactions and phase and structural transformations; in biological tissues and materials). Various types of these phenomena (heat and mass transfer; hydrodynamic and rheological effects; electromagnetic field propagation) are considered. Anomalous, relaxation and nonlinear transport, as well as transport induced by the impact of external fields and noise, is the focus of this issue. Modern methods of computational modelling, statistical physics and hydrodynamics, nonlinear dynamics and experimental methods are presented and discussed. Special attention is paid to transport phenomena in biological systems (such as haemodynamics in stenosed and thrombosed blood vessels magneto-induced heat generation and propagation in biological tissues, and anomalous transport in living cells) and to the development of a scientific background for progressive methods in cancer, heart attack and insult therapy (magnetic hyperthermia for cancer therapy, magnetically induced circulation flow in thrombosed blood vessels and non-contact determination of the local rate of blood flow in coronary arteries). The present issue includes works on the phenomenological study of transport processes, the derivation of a macroscopic governing equation on the basis of the analysis of a complicated internal reaction and the microscopic determination of macroscopic characteristics of the studied systems. This article is part of the theme issue ‘Transport phenomena in complex systems (part 1)’.

scholarly journals Transport phenomena in complex systems (part 2)

2022 ◽  
Vol 380 (2217) ◽  
Author(s):  
Dmitri V. Alexandrov ◽  
Andrey Yu. Zubarev
Keyword(s):  
Complex Systems ◽  
Numerical Simulations ◽  
Stochastic Analysis ◽  
State Of The Art ◽  
Transport Phenomena ◽  
Experimental Studies ◽  
Experimental Investigations ◽  
Nonlinear Transport ◽  
Microstructure Formation ◽  
Theme Issue

This theme issue, in two parts, continues research studies of transport phenomena in complex media published in the first part (Alexandrov & Zubarev 2021 Phil. Trans. R. Soc. A 379 , 20200301. ( doi:10.1098/rsta.2020.0301 )). The issue is concerned with theoretical, numerical and experimental investigations of nonlinear transport phenomena in heterogeneous and metastable materials of different nature, including biological systems. The papers are devoted to the new effects arising in such systems (e.g. pattern and microstructure formation in materials, impacts of external processes on their properties and evolution and so on). State-of-the-art methods of numerical simulations, stochastic analysis, nonlinear physics and experimental studies are presented in the collection of issue papers. This article is part of the theme issue ‘Transport phenomena in complex systems (part 2)’.

Computational Modelling and Simulation of Proton-Exchange Membrane Fuel Cells (Keynote)

2002 ◽  
Author(s):  
N. Djilali ◽  
T. Berning
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Transport Phenomena ◽  
Computational Modelling ◽  
Ambient Air ◽  
Gas Diffusion ◽  
Transport Processes ◽  
Proton Exchange ◽  
Exchange Membrane

Fuel cells (FC’s) are electrochemical devices that convert directly into electricity the chemical energy of reaction of a fuel (usually hydrogen) with an oxidant (usually oxygen from ambient air). The only by-products in a hydrogen fuel cell are heat and water, making this emerging technology the leading candidate for quiet, zero emission energy production. Several types of fuel cell are currently undergoing intense research and development for applications ranging from portable electronics and appliances to residential power generation and transportation. The focus of this lecture is Proton-Exchange Membrane Fuel Cells (PEMFC’s). An electrolyte consisting of a “solid” polymer membrane, low operating temperatures (typically below 90 °C) and a relatively simple design combine to make PEMFC’s particularly well suited to automotive and portable applications. The operation of a fuel cell relies on electrochemical reactions and an array of coupled transport phenomena, including multi-component gas flow, two phase-flow, heat and mass transfer, phase change and transport of charged species. The transport processes take place in variety of media, including porous gas diffusion electrodes and polymer membranes. The fuel cell environment makes it impossible to measure in-situ the quantities of interest to understand and quantify these phenomena, and computational modelling and simulations are therefore poised to play a central role in the development and optimization of fuel cell technology. We provide an overview of the role of various transport phenomena in fuel cell operation and some of the physical and computational modelling challenges they present. The processes will be illustrated through examples of multi-dimensional numerical simulations of Proton-Exchange Membrane Fuel Cells. We close with a perspective on some of the many remaining challenges and future development opportunities.

Transport Phenomena Analysis in Proton Exchange Membrane Fuel Cells

2005 ◽  
Vol 127 (12) ◽  
pp. 1363-1379 ◽  
Author(s):  
Hongtan Liu ◽  
Tianhong Zhou ◽  
Ping Cheng
Keyword(s):  
Experimental Investigation ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Transport Phenomena ◽  
Experimental Studies ◽  
Theoretical Models ◽  
Transport Processes ◽  
Proton Exchange ◽  
Exchange Membrane

The objective of this review is to provide a summary of modeling and experimental research efforts on transport phenomena in proton exchange membrane fuel cells (PEMFCs). Several representative PEMFC models and experimental studies in macro and micro PEMFCs are selected for discussion. No attempt is made to examine all the models or experimental studies, but rather the focus is to elucidate the macro-homogeneous modeling methodologies and representative experimental results. Since the transport phenomena are different in different regions of a fuel cell, fundamental phenomena in each region are first reviewed. This is followed by the presentation of various theoretical models on these transport processes in PEMFCs. Finally, experimental investigation on the cell performance of macro and micro PEMFC and DMFC is briefly presented.

Numerical modelling of igneous processes

2021 ◽  
Author(s):  
Tobias Keller
Keyword(s):  
Plate Tectonics ◽  
Experimental Studies ◽  
Computational Modelling ◽  
Mineral Resources ◽  
Transport Processes ◽  
Suspension Flow ◽  
Phase Reaction ◽  
Numerical Application ◽  
Multi Phase ◽  
Solid Liquid

<p>Magma matters. From magmatic differentiation of terrestrial planets into core, mantle and crust, to magmatism modulating plate tectonics and deep volatile cycles that maintain a habitable Earth, and volcanism causing terrible hazards but also providing rich energy and mineral resources – igneous processes are integral to the evolution of Earth and other terrestrial planetary bodies. Our understanding of volcanoes and their deep magmatic roots derives from a range of disciplines including field geology, experimental petrology, geochemical analyses, geophysical imaging, and volcano monitoring. Observational and experimental studies, however, are hampered by incomplete access to processes that play out across scales ranging from sub-millimetre size to thousands of kilometres, and from seconds to billions of years. Computational modelling provides a tool kit for investigating igneous processes across these scales.</p><p>Over the past decade, my research has been focused on advancing the theoretical description and numerical application of multi-phase reaction-transport processes at the volcano to planetary scale. Mixture theory provides a framework to represent the spatially averaged behaviour of a large sample of microscopic phase constituents including mineral grains, melt films, fluid droplets, and vapour bubbles. The approach has been used successfully to model both porous flow of melt percolating through compacting rock, as well as suspension flow of crystals settling in convecting magma bodies. My recent work has introduced a new modelling framework that bridges the porous to mushy and suspension flow limits, and extends beyond solid-liquid systems to multi-phase systems including several solid, liquid, and vapour phases. Igneous process modelling can thus provide new insights into the generation and extraction of mantle melts, the dynamics of crustal magma processing, the outgassing and eruption of shallow magma reservoirs, and the generation of mineral resources by exsolution of enriched magmatic liquids.</p>

Changes in the Parameters of the Electromagnetic Response of Model Dielectric Samples with Air Cavity Defects under External Deterministic Acoustic Impact

2021 ◽  
Vol 101 (1) ◽  
pp. 12-17
Author(s):  
D.D. Dann ◽  
◽  
M.V. Petrov ◽  
P.I. Fedotov ◽  
E.A. Sheveleva ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Dielectric Materials ◽  
Electromagnetic Response ◽  
Average Weight ◽  
Acoustic Excitation ◽  
Ball Impact ◽  
Electromagnetic Signals ◽  
Air Cavities ◽  
The Impact

The paper discusses the possibility of testing the air inclusions saturation in cement-sand samples using the acoustic-electrical transformations phenomenon in heterogeneous dielectric materials. An experiment technique is presented including contact external acoustic excitation and contactless registration of the electromagnetic response to such an impact. Methods of samples deterministic acoustic excitation by a ball impact and the experimental determination of the impact energy are described. The model samples size and composition are described, including air cavities in a polyethylene sheath. The experimental studies geometry is shown, indicating the direction of the samples acoustic excitation and the location of the electromagnetic receiving plates. It is shown that the defect-free samples and with air cavities, have different amplitude and frequency of the electromagnetic signals spectral components. The samples with air cavities have the average weight of the EMS spectrum changes towards lower frequencies. This frequency shift effectively reflects the concentration of air cavities defects in a cement-sand samples and this effect can be used when testing concrete products for the presence of air inclusions, and, accordingly, will allow determining the frost resistance of products.

Numerical modelling of igneous processes

2020 ◽  
Author(s):  
Tobias Keller
Keyword(s):  
Plate Tectonics ◽  
Experimental Studies ◽  
Computational Modelling ◽  
Mineral Resources ◽  
Transport Processes ◽  
Suspension Flow ◽  
Phase Reaction ◽  
Numerical Application ◽  
Multi Phase ◽  
Solid Liquid

<p>Magma matters. From magmatism facilitating the differentiation of terrestrial planets into core, mantle and crust, to the magmatic activity that modulates plate tectonics and deep volatile cycles to maintain a habitable Earth, to volcanism that causes terrible hazards but also provides rich energy and mineral resources – igneous processes are integral to Earth and other planets. Our understanding of volcanoes and their deep magmatic roots derives from a range of disciplines including field geology, petrology and geochemistry, and geophysical imaging. Observational and experimental studies, however, are hampered by incomplete access to processes that play out across scales ranging from sub-micron size to thousands of kilometres, and from seconds to billions of years. Computational modelling provides tools for investigating igneous processes across these scales.</p><p>Over the past decade, my research has been focused on advancing the theoretical description and numerical application of multi-phase reaction–transport processes at the volcano to planetary scale. Mixture theory provides a framework to represent the spatially averaged behaviour of a large sample of microscopic phase constituents such as mineral grains, melt films, and vapour bubbles. This approach has been used successfully to model both porous flow of melt percolating through compacting partially molten rock, as well as suspension flow of crystals settling in convecting magma bodies. My recent work has introduced a new modelling framework to bridge the porous and suspension flow limits, and to extend beyound solid-liquid systems to multi-phase systems including several solid, liquid, and vapour phases. These advances provide new insights into the dynamics of crustal mush bodies, the outgassing and eruption of shallow magma reservoirs, and the generation of mineral resources by exsolution of exotic magmatic liquids.</p>

scholarly journals Material and Structural Modeling Aspects of Brain Tissue Deformation under Dynamic Loads

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 271 ◽  
Author(s):  
Monika Ratajczak ◽  
Mariusz Ptak ◽  
Leszek Chybowski ◽  
Katarzyna Gawdzińska ◽  
Romuald Będziński
Keyword(s):  
Brain Tissue ◽  
Human Subjects ◽  
Experimental Studies ◽  
Material Modeling ◽  
Geometrical Parameters ◽  
Dynamic Loading Conditions ◽  
Technological Improvements ◽  
The Impact ◽  
The Brain

The aim of this work was to assess the numerous approaches to structural and material modeling of brain tissue under dynamic loading conditions. The current technological improvements in material modeling have led to various approaches described in the literature. However, the methods used for the determination of the brain’s characteristics have not always been stated or clearly defined and material data are even more scattered. Thus, the research described in this paper explicitly underlines directions for the development of numerical brain models. An important element of this research is the development of a numerical model of the brain based on medical imaging methods. This approach allowed the authors to assess the changes in the mechanical and geometrical parameters of brain tissue caused by the impact of mechanical loads. The developed model was verified through comparison with experimental studies on post-mortem human subjects described in the literature, as well as through numerical tests. Based on the current research, the authors identified important aspects of the modeling of brain tissue that influence the assessment of the actual biomechanical response of the brain for dynamic analyses.

EXPERIMENTAL AND NUMERICAL INVESTIGATION ON MANUFACTURING METHODS OF POWDER METALLURGY COMPONENTS WITH INTEGRATED INFORMATION STORAGE

2011 ◽  
Vol 10 (01) ◽  
pp. 11-20
Author(s):  
BERND-ARNO BEHRENS ◽  
NAJMEH VAHED ◽  
EDIN GASTAN ◽  
FABIAN LANGE
Keyword(s):  
Research Work ◽  
Experimental Studies ◽  
Information Storage ◽  
Research Centre ◽  
Specific Data ◽  
Data Carrier ◽  
Foreign Materials ◽  
The Impact ◽  
Sintering Processes

This paper presents a research work within Collaborative Research Centre 653 "Gentelligent Components in Their Lifecycle." The term "gentelligent" refers to the genetic and intelligent character of these components. Specific data are inherently saved in the components, which are used during its lifecycle for the means of identification, processing, and reproduction. The present study aims at the development of a method to manufacture and utilize gentelligent sintered parts. As data carrier, foreign materials shaped in fonts, logos, or codes are embedded in the powder material proceeded by pressing and sintering processes. The foreign material can be applied in forms of particles or compound powder. The information read-out is based on radiographic methods. The objectives of the investigations are the determination of the process parameters of each method and the impact of the integrated foreign materials on the mechanical properties of the component. The experimental studies are supported by numerical simulations.

scholarly journals Experimental research of the air permeability of concrete in the compressed zone of the containment for power units no. 1, 2 of the South-Ukrainian NPP

2021 ◽  
Vol 20 ◽  
pp. 39-50
Author(s):  
Ia. A. Zhygalov ◽  
◽  
V. V. Inyushev ◽  
V. O. Posokh ◽  
S. A. Vyzhva ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Air Permeability ◽  
Complex Stress State ◽  
Air Pressure ◽  
Design Basis ◽  
Design Basis Accident ◽  
The Impact ◽  
Experimental Researches ◽  
Maximum Design

The determination of the air permeability of concrete in the compressed zone of NPP’s containment under conditions of excessive air pressure in the subshell space of the reactor compartment under a maximum design basis accident is necessary to confirm the localizing functions of the containment when extending the lifetime of power units. Approaches to determining the localizing ability (air permeability) of concrete in the compressed zone of the containment of NPPs with WWER-1000 type reactors under the impact of excessive air pressure under conditions of maximum design basis accident are discussed in the article. The designed testing installation for experimental studies of the air permeability of concrete by the method of stationary radial filtration is described and the results of experimental researches of the air permeability on the installation are presented for samples simulating the composition of concrete used under construction of the containment for Power Units No. 1, 2 (series B-302 and B-338, respectively) SD “South-Ukrainian NPP”. A comparative analysis of the results of abovementioned experimental researches with the results of experimental and theoretical work on the study of air permeability of the similar samples-imitators of concrete by the method of stationary linear filtration, as well as the results of measurements for samples of concrete sampled directly from the compressed zone of containment for Power Unit No. 2 of SD “South-Ukrainian NPP” was fulfilled. The results are explained by processes of compaction of the concrete structure under a complex stress state that occurs under specific hardening conditions and during longtime compression by pre-stressed reinforcing ropes, which takes place under conditions of real containment operation. It was concluded that the simulators made according to the currently accepted technology cannot provide a correct determination of the localizing ability of the NPP’s containment, since the conditions and time of containment concrete hardening, as well as the longtime constant compressive action of reinforcing ropes, cannot be correctly modeled in full under the formation of samples-imitators. The issue of the containment concrete samplesimitators creating in laboratory conditions requires additional study, improvement of technology and the development of new approaches with maximum physical modeling of the conditions characteristic of the operation of the NPP containment.

Manufacturing Method of PM Components with Integrated Information Storage

2010 ◽  
Vol 44-47 ◽  
pp. 915-919 ◽  
Author(s):  
Bernd Arno Behrens ◽  
Najmeh Vahed ◽  
Edin Gastan ◽  
Fabian Lange
Keyword(s):  
Research Work ◽  
Experimental Studies ◽  
Information Storage ◽  
Research Centre ◽  
Specific Data ◽  
Manufacturing Method ◽  
Foreign Materials ◽  
The Impact ◽  
Sintering Processes

This paper presents a research work within Collaborative Research Centre 653 “Gentelligent Components in Their Lifecycle”. The term “gentelligent” refers to the genetic and intelligent character of these components. Specific data are inherently saved in the components which are used during its lifecycle for the means of identification, processing and reproduction. The presented study aims for the development of a method to manufacture and utilize gentelligent sintered parts. As data carrier, foreign materials shaped in fonts, logos or codes, are embedded in the powder material proceeded by pressing and sintering processes. The foreign material can be applied in forms of particles or compound powder. The information read-out is based on radiographic methods. The objectives of the investigations are the determination of the process parameters of each method and the impact of the integrated foreign materials on the mechanical properties of the component. The experimental studies are supported by numerical simulations.

Sign in / Sign up

Export Citation Format

Share Document