scholarly journals Fluid Dynamics Experiments for Planetary Interiors

2021 ◽  
Author(s):  
Michael Le Bars ◽  
Ankit Barik ◽  
Fabian Burmann ◽  
Daniel P. Lathrop ◽  
Jerome Noir ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Laboratory Experiments ◽  
Fluid Flows ◽  
Review Article ◽  
Planetary Interiors ◽  
Numerical Studies ◽  
Long Duration ◽  
Planetary Cores ◽  
Experimental Approaches ◽  
Do So

AbstractUnderstanding fluid flows in planetary cores and subsurface oceans, as well as their signatures in available observational data (gravity, magnetism, rotation, etc.), is a tremendous interdisciplinary challenge. In particular, it requires understanding the fundamental fluid dynamics involving turbulence and rotation at typical scales well beyond our day-to-day experience. To do so, laboratory experiments are fully complementary to numerical simulations, especially in systematically exploring extreme flow regimes for long duration. In this review article, we present some illustrative examples where experimental approaches, complemented by theoretical and numerical studies, have been key for a better understanding of planetary interior flows driven by some type of mechanical forcing. We successively address the dynamics of flows driven by precession, by libration, by differential rotation, and by boundary topography.

Influence of urban forms on long-duration urban flooding: laboratory experiments and computational analysis

2021 ◽  
pp. 127034
Author(s):  
Xuefang Li ◽  
Sébastien Erpicum ◽  
Emmanuel Mignot ◽  
Pierre Archambeau ◽  
Michel Pirotton ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Computational Analysis ◽  
Urban Flooding ◽  
Urban Forms ◽  
Long Duration

scholarly journals Computational Fluid Dynamics (CFD) as a tool for the analysis of ventilation and indoor microclimate in agricultural buildings

1997 ◽  
Vol 45 (1) ◽  
pp. 81-96 ◽  
Author(s):  
A. Mistriotis ◽  
T. De Jong ◽  
M.J.M. Wagemans ◽  
G.P.A. Bot
Keyword(s):  
Fluid Dynamics ◽  
Laboratory Experiments ◽  
Numerical Technique ◽  
Design Tool ◽  
Indoor Climate ◽  
Pressure Coefficients ◽  
Computational Fluid Dynamics Cfd ◽  
Basic Concepts ◽  
Experimental Values ◽  
Broiler House

The basic concepts of CFD are presented in relation to applications in modelling the ventilation process and the resulting indoor climate of agricultural buildings. The validity and the advantages of this numerical technique are presented using 3 examples. Firstly the pressure coefficients along the roof of a 7-span Venlo-type greenhouse were calculated and compared with the corresponding experimental values. Next, the ventilation process in a single-span greenhouse was investigated and the results were compared to laboratory experiments. Finally, the use of CFD as a design tool for more efficient ventilation systems was demonstrated for the case of a broiler house.

Secondary fluid flows driven electromagnetically in a two-dimensional extended duct

2005 ◽  
Vol 461 (2058) ◽  
pp. 1659-1683 ◽  
Author(s):  
Zhi-Min Chen ◽  
W.G Price
Keyword(s):  
Steady State ◽  
Laboratory Experiments ◽  
Fluid Motion ◽  
Fluid Flows ◽  
Two Dimensional ◽  
Slip Boundary Conditions ◽  
Slip Boundary ◽  
Wave Numbers ◽  
Motion Problem ◽  
Secondary Fluid

This study focuses on two-dimensional fluid flows in a straight duct with free-slip boundary conditions applied on the channel walls y =0 and y =2 πN with N >1. In this extended wall-bounded fluid motion problem, secondary fluid flow patterns resulting from steady-state and Hopf bifurcations are examined and shown to be dependent on the choice of longitudinal wave numbers. Some secondary steady-state flows appear at specific wave numbers, whereas at other wave numbers, both secondary steady-state and self-oscillation flows coexist. These results, derived through analytical arguments and truncation series approximation, are confirmed by simple numerical experiments supporting the findings observed from laboratory experiments.

scholarly journals Axisymmetric simulation of viscoelastic filament thinning with the Oldroyd-B model

2018 ◽  
Vol 851 ◽  
Author(s):  
Emre Turkoz ◽  
Jose M. Lopez-Herrera ◽  
Jens Eggers ◽  
Craig B. Arnold ◽  
Luc Deike
Keyword(s):  
Stress Component ◽  
Fluid Flows ◽  
Theoretical Description ◽  
Slender Body ◽  
Complex Materials ◽  
Two Phase ◽  
Practical Applications ◽  
Numerical Studies ◽  
Fundamental Understanding ◽  
The One

A fundamental understanding of the filament thinning of viscoelastic fluids is important in practical applications such as spraying and printing of complex materials. Here, we present direct numerical simulations of the two-phase axisymmetric momentum equations using the volume-of-fluid technique for interface tracking and the log-conformation transformation to solve the viscoelastic constitutive equation. The numerical results for the filament thinning are in excellent agreement with the theoretical description developed with a slender body approximation. We show that the off-diagonal stress component of the polymeric stress tensor is important and should not be neglected when investigating the later stages of filament thinning. This demonstrates that such numerical methods can be used to study details not captured by the one-dimensional slender body approximation, and pave the way for numerical studies of viscoelastic fluid flows.

Advances in fixed-bed reactor modeling using particle-resolved computational fluid dynamics (CFD)

2019 ◽  
Vol 35 (2) ◽  
pp. 139-190 ◽  
Author(s):  
Nico Jurtz ◽  
Matthias Kraume ◽  
Gregor D. Wehinger
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fixed Bed ◽  
Review Article ◽  
Catalyst Design ◽  
Fixed Bed Reactor ◽  
Reactor Modeling ◽  
Catalytic Systems ◽  
Heterogeneous Catalytic ◽  
Computational Fluid Dynamics Cfd

Abstract In 2006, Dixon et al. published the comprehensive review article entitled “Packed tubular reactor modeling and catalyst design using computational fluid dynamics.” More than one decade later, many researchers have contributed to novel insights, as well as a deeper understanding of the topic. Likewise, complexity has grown and new issues have arisen, for example, by coupling microkinetics with computational fluid dynamics (CFD). In this review article, the latest advances are summarized in the field of modeling fixed-bed reactors with particle-resolved CFD, i.e. a geometric resolution of every pellet in the bed. The current challenges of the detailed modeling are described, i.e. packing generation, meshing, and solving with an emphasis on coupling microkinetics with CFD. Applications of this detailed approach are discussed, i.e. fluid dynamics and pressure drop, dispersion, heat and mass transfer, as well as heterogeneous catalytic systems. Finally, conclusions and future prospects are presented.

Towards astrobiological experimental approaches to study planetary UV surface environments

2018 ◽  
Vol 14 (S345) ◽  
pp. 222-226
Author(s):  
Ximena C. Abrevaya ◽  
Martin Leitzinger ◽  
Oscar J. Oppezzo ◽  
Petra Odert ◽  
G. Juan M. Luna ◽  
...  
Keyword(s):  
Ultraviolet Radiation ◽  
Laboratory Experiments ◽  
Lethal Dose ◽  
Action Spectrum ◽  
Interdisciplinary Approach ◽  
Accurate Estimation ◽  
Atmospheric Attenuation ◽  
Approaches To Study ◽  
Experimental Approaches ◽  
The Impact

AbstractThe stellar ultraviolet radiation (UVR) has been studied in the last decade and has been found to be an important factor to determine the habitability of planetary surfaces. It is known that UVR can be a constraint for life. However, most of the studies of UVR and habitability have missed some fundamental aspects: i) Accurate estimation of the planetary atmospheric attenuation, ii) The biological inferences used to represent the impact of the stellar UVR on life are theoretical and based on the action spectrum (for DNA or microorganisms) or considering parameters as the “lethal dose” obtained from non-astrobiological experiments. Therefore, the conclusions reached by previous studies about the UVR habitability of planetary bodies may be inaccurate. In this work, we propose how to address these studies in a more accurate way through an interdisciplinary approach that combines astrophysics, microbiology, and photobiology and by the use of specially designed laboratory experiments.

Simulation of an Effect of a Baffle Length on the Power Consumption in an Agitated Vessel

2008 ◽  
Vol 4 (2) ◽  
Author(s):  
Palani Sivashanmugam ◽  
S. Prabhakaran
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Turbulence Modeling ◽  
Fluid Flows ◽  
Power Number ◽  
Food Industries ◽  
Agitated Vessel ◽  
Computational Fluid Dynamics Cfd ◽  
Miscible Liquids

Agitated vessels are often used for homogenization of the miscible liquids in chemical, biochemical, and food industries. Computational fluid dynamics (CFD) is a useful tool for studying fluid flows, including those of mixing systems. It is particularly powerful where the ability exists to corroborate model results with available data. The CFD simulation was carried out for Rushton and Smith turbines agitators. The standard k-? model has been used for turbulence modeling. The data obtained by simulation are matching with the literature experimental value for standard baffle with the discrepancy of less than +_4.5% for power number. The simulated results for agitated vessel with short baffle (non-standard) are agreeing with the literature values within plus or minus 5% for Power Number.

scholarly journals Physiological tolerances account for range limits and abundance structure in an invasive slug

2009 ◽  
Vol 276 (1661) ◽  
pp. 1459-1468 ◽  
Author(s):  
Jennifer E Lee ◽  
Charlene Janion ◽  
Elrike Marais ◽  
Bettine Jansen van Vuuren ◽  
Steven L Chown
Keyword(s):  
Laboratory Experiments ◽  
Climatic Factors ◽  
Range Limits ◽  
Sensitive Species ◽  
Species Preference ◽  
Absolute Limit ◽  
Drainage Line ◽  
Physiological Tolerances ◽  
Linear Decline ◽  
Do So

Despite the importance of understanding the mechanisms underlying range limits and abundance structure, few studies have sought to do so. Here we use a terrestrial slug species, Deroceras panormitanum , that has invaded a remote, largely predator-free, Southern Ocean island as a model system to do so. Across Marion Island, slug density does not conform to an abundant centre distribution. Rather, abundance structure is characterized by patches and gaps. These are associated with this desiccation-sensitive species' preference for biotic and drainage line habitats that share few characteristics except for their high humidity below the vegetation surface. The coastal range margin has a threshold form, rapidly rising from zero to high density. Slugs do not occur where soil-exchangeable Na values are higher than 3000 mg kg −1 , and in laboratory experiments, survival is high below this value but negligible above it. Upper elevation range margins are a function of the inability of this species to survive temperatures below an absolute limit of −6.4°C, which is regularly exceeded at 200 m altitude, above which slug density declines to zero. However, the linear decline in density from the coastal peak is probably also a function of a decline in performance or time available for activity. This is probably associated with an altitudinal decline in mean annual soil temperature. These findings support previous predictions made regarding the form of density change when substrate or climatic factors set range limits.

scholarly journals Research of velocity field in vessel’s wake current from «side by side» mooring

2020 ◽  
Author(s):  
Е.Ю. Чебан ◽  
Д.В. Никущенко ◽  
О.В. Мартемьянова ◽  
Н.Е. Зотова
Keyword(s):  
Laboratory Experiments ◽  
Field Experiments ◽  
Fluid Velocity ◽  
Fluid Flows ◽  
Relative Displacement ◽  
Water Area ◽  
Hull Form ◽  
Sensor Field ◽  
Flow Velocity Measurement ◽  
Hull Forms

В настоящей работе приведены результаты исследования полей скоростей, возникающие при обтекании потоком жидкости судов в счале в зависимости от формы корпуса судов, расстояния между ними и относительного смещения корпусов судов лабораторными, натурными и численными методами. Лабораторные эксперименты выполнялись с применением ADV-датчика. Натурные эксперименты проводились на акватории р. Волга с двумя танкерами. Для численного моделирования использовался программный комплекс FineMarineTM. Выполненное сопоставление результатов измерений скорости потока различными методами, показало достаточную сходимость результатов. Получено, что для моделей судов с упрощенными обводами характер спутного потока жидкости существенно зависит от расстояния между моделями. Показано, что увеличение расстояния между судами может приводить к значительному увеличению скорости спутного течения в раннем следе за счаленными корпусами, но при относительном продольном смещении судов такой картины не наблюдается. This work presents the results of the study of velocity fields that occur when a stream of fluid flows along “side by side” vessels’ mooring, depending on the hull forms, the distance between them and the relative displacement of the hull by laboratory, full-sized and numerical methods. Laboratory experiments were performed using an ADV-sensor. Field experiments were conducted with two tankers in the water area of ​​the river Volga. The FineMarineTM software package was used for numerical simulation. A correlation of the results of the flow velocity measurement by various methods showed sufficient convergence of the results. It was found that the cocurrent stream of fluid pattern for models of vessels with simplistic hull form depends heavily on the distance between the models. It is shown that an increase in the distance between the vessels can lead to a significant increase in the fluid velocity of the concurrent stream in the early wake of the hulls of vessels’ mooring, but this picture is not observed with a relative longitudinal displacement of the vessels.

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