Ano (2918)
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Exploring Bubble Dynamics with VOF Method Simulations: Insights from Two Fundamental Gas-Liquid Flow Case Studies
Harrandt, Václav
2024 - anglický
The present study focuses on the flow of Taylor bubbles, representing the interaction between the channel wall and the gas phase, and the collision of\na bubble with a vortex ring, serving as a model liquid-gas interaction. Understanding the former case can be essential to prevent the membrane\nfouling or the flow induced corrosion. The dynamics of the latter case is the predictive criterion for whether the initial mother bubble will break up into the daughter bubbles or not2 and this process can therefore be used as an idealized model of turbulent bubble flow.
Klíčová slova:
bubble dynamics; multiphase interaction,; numerical simulation
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Exploring Bubble Dynamics with VOF Method Simulations: Insights from Two Fundamental Gas-Liquid Flow Case Studies
The present study focuses on the flow of Taylor bubbles, representing the interaction between the channel wall and the gas phase, and the collision of\na bubble with a vortex ring, serving as a model ...
The Influence of Geometric Parameters of 3D Printed Structured Beds on Hydrodynamic Characteristics of Trickle-Bed Reactor
Nyklíčková, Kateřina
2024 - anglický
The study examines a parametric set of POCS structures, where cubic cell is the basic element. The parameters such as strut diameter sd and cell size cs were varied1. These modifications are implemented with an emphasis on maintaining similar porosity and specific surface area for these structures.
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
The Influence of Geometric Parameters of 3D Printed Structured Beds on Hydrodynamic Characteristics of Trickle-Bed Reactor
The study examines a parametric set of POCS structures, where cubic cell is the basic element. The parameters such as strut diameter sd and cell size cs were varied1. These modifications are ...
Finite element approximation of fluid structure interaction using Taylor-Hood and Scott-Vogelius elements
Vacek, Karel; Sváček, P.
2024 - anglický
This paper addresses the problem of fluid flow interacting a vibrating solid cylinder described by one degree of freedom system and with fixed airfoil. The problem is described by the incompressible Navier-Stokes equations written in the arbitrary Eulerian-Lagrangian (ALE) formulation. The ALE mapping is constructed with the use of a pseudo-elastic approach. The flow problem is numerically approximated by the finite element method (FEM). For discretization of the fluid flow, the results obtained by both the Taylor-Hood (TH) element and the Scott-Vogelius (SV) finite element are compared. The TH element satisfies the Babuška-Brezzi inf-sup condition, which guarantees the stability of the scheme. In the case of the SV element the mesh, that is created as a barycentric refinement of regular triangulation, is used to satisfy the Babuška-Brezzi condition. The numerical results for two benchmark problems are shown.
Klíčová slova:
finite element method; arbitrary Lagrangian-Eulerian method; Scott-Vogelius element; Taylor-Hood element
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Finite element approximation of fluid structure interaction using Taylor-Hood and Scott-Vogelius elements
This paper addresses the problem of fluid flow interacting a vibrating solid cylinder described by one degree of freedom system and with fixed airfoil. The problem is described by the incompressible ...
The American origin of the French Revolution
Ottinger, Sebastian; Rosenberger, L.
2024 - anglický
We show that the French combatants’ exposure to the United States increased support for the French Revolution a decade later. French regions from which more American combatants originated had more revolts against feudal institutions, revolutionary societies, volunteers for the revolutionary army, and emigrants from the Old Regime’s elite. To establish causality, we exploit two historical coincidences: i) originally, a French army of seven and a half thousand was ready to sail, but one-third did not, ii) among those deployed, only some regiments were stationed in New England. Only combatants exposed to New England affected the French Revolution after their return.
Klíčová slova:
institutional change; French Revolution; American War of Independence
Dokument je dostupný na externích webových stránkách.
The American origin of the French Revolution
We show that the French combatants’ exposure to the United States increased support for the French Revolution a decade later. French regions from which more American combatants originated had more ...
Survey expectations, adaptive learning and inflation dynamics
Rychalovska, Y.; Slobodyan, Sergey; Wouters, R.
2024 - anglický
The use of survey information on inflation expectations as an observable in a DSGE model can substantially refine identification of the shocks that drive inflation. Optimal integration of the survey information improves the model forecast for inflation and for other macroeconomic variables. Models with expectations based on an Adaptive Learning setup can exploit survey information more efficiently than their Rational Expectations counterparts. The resulting time-variation in the perceived inflation target, in inflation persistence, and in the sensitivity of inflation to various shocks provide a rich and consistent description of the joint dynamics of realized and expected inflation. Our framework produces a reasonable interpretation of the post-Covid inflation dynamics. Our learning model successfully identifies the more persistent nature of the recent inflation surge.
Klíčová slova:
inflation; expectations; survey data
Dokument je dostupný na externích webových stránkách.
Survey expectations, adaptive learning and inflation dynamics
The use of survey information on inflation expectations as an observable in a DSGE model can substantially refine identification of the shocks that drive inflation. Optimal integration of the survey ...
Emerging Contaminants in Sewage Sludge: Analysis and Their Removal by Pyrolysis
Hušek, Matěj
2024 - anglický
The study continues with flame retardants (e.g., phosphorus-based or brominated) present in sludge, which may pose a hazard to nature and human health3,4. There is a lack of information on their pyrolysis removal and occurrence in the sludge in the Czech Republic.
Klíčová slova:
sewage sludge; pyrolysis; PFAS; flame retardants
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Emerging Contaminants in Sewage Sludge: Analysis and Their Removal by Pyrolysis
The study continues with flame retardants (e.g., phosphorus-based or brominated) present in sludge, which may pose a hazard to nature and human health3,4. There is a lack of information on their ...
Cholinium Based Ionic Liquids: Influence of Water as a Co-solvent on Their Physico-chemical Properties and Preliminary Results for Dissolution of Biopolymers
Souvenir Zafindrajaona, Mahasoa-Salina
2024 - anglický
Ionic liquids (ILs) are emerging as promising alternative solvents in the field of natural substance extraction, offering significant advantages over traditional solvents. Since the last decade, we notice the increasing use of greener solvent alternatives such as Natural Deep Eutectic Solvents (NaDES) or ILs for the extraction of highly valuable compounds from natural sources such as lignocellulose. During this presentation, the influence of water on heat capacity, density, speed of sound and TGA will be discussed and the preliminary results for lignin dissolution willbe presented.
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Cholinium Based Ionic Liquids: Influence of Water as a Co-solvent on Their Physico-chemical Properties and Preliminary Results for Dissolution of Biopolymers
Ionic liquids (ILs) are emerging as promising alternative solvents in the field of natural substance extraction, offering significant advantages over traditional solvents. Since the last decade, we ...
14th International Bordetella Symposium
Šebo, Peter
2024 - anglický
We shall discuss the latest research achievements in the Bordatella/pertussis filed and how to tackle the challenge of current pertussis resurgence. We will assess what needs to be done to overcome the limitations of current acellular pertussis vaccines in order to curb the resurgence and transmission of whoopong cough.
Klíčová slova:
bordetella; petrussis; vaccine
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
14th International Bordetella Symposium
We shall discuss the latest research achievements in the Bordatella/pertussis filed and how to tackle the challenge of current pertussis resurgence. We will assess what needs to be done to overcome ...
Flow simulations approach for flocculation tanks
Idžakovičová, Kristýna; Bílek, Vojtěch; Haidl, Jan; Isoz, M.; Pivokonský, Martin
2024 - anglický
Flocculation in water treatment facilities plays a key role in the separation of colloidal inorganic and organic substances. Its optimization leads to a significant increase in its efficiency and savings of operational costs. However, it is currently based on trial-and-error experimental approaches. In this contribution, we focus on flow modeling in stirred flocculation tanks that would, after coupling with a calibrated model of particle aggregation, enable simulationbased flocculation optimization. Despite the abundance of literature on stirred tank modeling, there is no universal agreement on the methodology used to describe turbulence nor on the approach to the computational mesh creation. Consequently, there is no unified methodology for simulations and their validation. To address this, we present a best-practice methodology for economical, yet reliable flow simulations in the said device. This methodology includes the choice of the turbulence model, the approach to the design of a high quality mesh suitable for arbitrary geometries, and results evaluation. It is developed based on an extensive literature review, a multitude of flow simulations using several meshes of progressively higher quality and resolution, and various strategies to converge to steady-state flow conditions. The simulation quality indicators used here involve comparison with the experimental data on fluid velocity, stirrer power output, and flow rate through the impeller zone. Additionally, the resulting flow simulation models are compared using tracer transport simulations, hinting at their potential for coupling with particle aggregation models.
Klíčová slova:
flocculation tank; stirring; MRF; CFD; OpenFOAM
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Flow simulations approach for flocculation tanks
Flocculation in water treatment facilities plays a key role in the separation of colloidal inorganic and organic substances. Its optimization leads to a significant increase in its efficiency and ...
COVID-19 and political preferences through stages of the pandemic: the case of the Czech Republic
Bičáková, Alena; Jurajda, Štěpán
2024 - anglický
We track the effects of the COVID-19 pandemic on political preferences through ‘high’ and ‘low’ phases of the pandemic. We ask about the effects of the health and the economic costs of the pandemic measured at both personal and municipality levels. Consistent with the literature, we estimate effects suggestive of political accountability of leaders during ‘high’ pandemic phases. However, we also find that the pandemic political accountability effects are mostly short-lived, and do not extend to the first post-pandemic elections.
Klíčová slova:
COVID-19; political preferences; election outcomes
Dokument je dostupný na externích webových stránkách.
COVID-19 and political preferences through stages of the pandemic: the case of the Czech Republic
We track the effects of the COVID-19 pandemic on political preferences through ‘high’ and ‘low’ phases of the pandemic. We ask about the effects of the health and the economic costs of the pandemic ...
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