scholarly journals A Computational Fluid Dynamics Model for the Small-Scale Dynamics of Wave, Ice Floe and Interstitial Grease Ice Interaction

Fluids ◽  
2021 ◽  
Vol 6 (5) ◽  
pp. 176
Author(s):  
Rutger Marquart ◽  
Alfred Bogaers ◽  
Sebastian Skatulla ◽  
Alberto Alberello ◽  
Alessandro Toffoli ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Sea Ice ◽  
Strain Rate ◽  
Large Scale ◽  
Ocean Waves ◽  
Small Scale ◽  
Drag Forces ◽  
Marginal Ice Zone ◽  
Ice Floes

The marginal ice zone is a highly dynamical region where sea ice and ocean waves interact. Large-scale sea ice models only compute domain-averaged responses. As the majority of the marginal ice zone consists of mobile ice floes surrounded by grease ice, finer-scale modelling is needed to resolve variations of its mechanical properties, wave-induced pressure gradients and drag forces acting on the ice floes. A novel computational fluid dynamics approach is presented that considers the heterogeneous sea ice material composition and accounts for the wave-ice interaction dynamics. Results show, after comparing three realistic sea ice layouts with similar concentration and floe diameter, that the discrepancy between the domain-averaged temporal stress and strain rate evolutions increases for decreasing wave period. Furthermore, strain rate and viscosity are mostly affected by the variability of ice floe shape and diameter.

Detailed Analysis of the Wake Structure of a Straight-Blade H-Darrieus Wind Turbine by Means of Wind Tunnel Experiments and Computational Fluid Dynamics Simulations

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Alessandro Bianchini ◽  
Francesco Balduzzi ◽  
Giovanni Ferrara ◽  
Lorenzo Ferrari ◽  
Giacomo Persico ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Wind Turbines ◽  
Large Scale ◽  
Vertical Axis ◽  
Performance Estimation ◽  
Small Scale ◽  
Dynamics Simulations

Darrieus vertical axis wind turbines (VAWTs) have been recently identified as the most promising solution for new types of applications, such as small-scale installations in complex terrains or offshore large floating platforms. To improve their efficiencies further and make them competitive with those of conventional horizontal axis wind turbines, a more in depth understanding of the physical phenomena that govern the aerodynamics past a rotating Darrieus turbine is needed. Within this context, computational fluid dynamics (CFD) can play a fundamental role, since it represents the only model able to provide a detailed and comprehensive representation of the flow. Due to the complexity of similar simulations, however, the possibility of having reliable and detailed experimental data to be used as validation test cases is pivotal to tune the numerical tools. In this study, a two-dimensional (2D) unsteady Reynolds-averaged Navier–Stokes (U-RANS) computational model was applied to analyze the wake characteristics on the midplane of a small-size H-shaped Darrieus VAWT. The turbine was tested in a large-scale, open-jet wind tunnel, including both performance and wake measurements. Thanks to the availability of such a unique set of experimental data, systematic comparisons between simulations and experiments were carried out for analyzing the structure of the wake and correlating the main macrostructures of the flow to the local aerodynamic features of the airfoils in cycloidal motion. In general, good agreement on the turbine performance estimation was constantly appreciated.

scholarly journals Ocean wave speed in the Antarctic marginal ice zone

2001 ◽  
Vol 33 ◽  
pp. 350-354 ◽  
Author(s):  
Colin Fox ◽  
Tim G. Haskell
Keyword(s):  
Wave Propagation ◽  
Large Scale ◽  
Wave Speed ◽  
Ross Sea ◽  
Ocean Waves ◽  
Wave Speeds ◽  
Marginal Ice Zone ◽  
Scale Properties ◽  
Ice Floes ◽  
The Antarctic

AbstractThe propagation of ocean waves in the marginal ice zone (MIZ) is investigated with the aim of determining whether the loading and scattering of waves by ice floes is significant. Measurements made using instrumented ice floes in the MIZ north of the Ross Sea, Antarctica, during June 1998 are used to determine the frequency-wavelength relationship for propagating ocean waves in that region. This measured-dispersion equation is related to the effective large-scale properties of the MIZ that occur in models for wave propagation and scattering. We present the measured wave speeds to enable estimation of the parameters in these models.

scholarly journals WIFF1.0: A hybrid machine-learning-based parameterization of Wave-Induced sea-ice Floe Fracture

2021 ◽  
Author(s):  
Christopher Horvat ◽  
Lettie A. Roach
Keyword(s):  
Sea Ice ◽  
Climate Models ◽  
Ocean Surface ◽  
Ocean Waves ◽  
Ocean Surface Waves ◽  
Marginal Ice Zone ◽  
Ice Floes ◽  
Global Statistics ◽  
Surface Wave Field ◽  
Wave Induced

Abstract. Ocean surface waves play an important role in maintaining the marginal ice zone, a heterogenous region occupied by sea ice floes with variable horizontal sizes. The location, width, and evolution of the marginal ice zone is determined by the mutual interaction of ocean waves and floes, as waves propagate into the ice, bend it, and fracture it. In previous work, we developed a one-dimensional “superparameterized” scheme to simulate the interaction between the stochastic ocean surface wave field and sea ice. As this method is computationally expensive and not bitwise reproducible, here we use a pair of neural networks to accelerate this parameterization, delivering an adaptable, computationally-inexpensive, reproducible approach for simulating stochastic wave-ice interactions. Implemented in the sea ice model CICE, this accelerated code reproduces global statistics resulting from the full wave fracture code without increasing computational overheads. The combined model, Wave-Induced Floe Fracture (WIFF v1.0) is publicly available and may be incorporated into climate models that seek to represent the effect of waves fracturing sea ice.

scholarly journals From numerical prototypes to real models: a progressive study of aerodynamic parameters of nonconventional concrete structures with Computational Fluid Dynamics

2020 ◽  
Vol 13 (3) ◽  
pp. 628-643
Author(s):  
C. V. S. SARMENTO ◽  
A. O. C. FONTE ◽  
L. J. PEDROSO ◽  
P. M. V. RIBEIRO
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Performance ◽  
Large Scale ◽  
Computational Models ◽  
Computational Cost ◽  
Concrete Structures ◽  
Navier Stokes ◽  
Small Scale ◽  
Aerodynamic Parameters

Abstract The practical evaluation of aerodynamic coefficients in unconventional concrete structures requires specific studies, which are small-scale models evaluated in wind tunnels. Sophisticated facilities and special sensors are needed, and the tendency is for modern and slender constructions to arise with specific demands on their interaction with the wind. On the other hand, the advances obtained in modern multi-core processors emerge as an alternative for the construction of sophisticated computational models, where the Navier-Stokes differential equations are solved for fluid flow using numerical methods. Computations of this kind require specialized theoretical knowledge, efficient computer programs, and high-performance computers for large-scale calculations. This paper presents recent results involving two real-world applications in concrete structures, where the aerodynamic parameters were estimated with the aid of computational fluid dynamics. Conventional quad-core computers were applied in simulations with the Finite Volume Method and a progressive methodology is presented, highlighting the main aspects of the simulation and allowing its generalization to other types of problems. The results confirm that the proposed methodology is promising in terms of computational cost, drag coefficient estimation and versatility of simulation parameters. These results also indicate that mid-performance computers can be applied for preliminary studies of aerodynamic parameters in design offices.

scholarly journals On the effects of membrane viscosity on transient red blood cell dynamics

Soft Matter ◽  
2020 ◽  
Vol 16 (26) ◽  
pp. 6191-6205 ◽  
Author(s):  
Fabio Guglietta ◽  
Marek Behr ◽  
Luca Biferale ◽  
Giacomo Falcucci ◽  
Mauro Sbragaglia
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Blood Circulation ◽  
Hydraulic Properties ◽  
Large Scale ◽  
Mechanical Response ◽  
Cell Dynamics ◽  
Membrane Viscosity

Computational Fluid Dynamics is currently used to design and improve the hydraulic properties of biomedical devices, wherein the large scale blood circulation needs to be simulated by accounting for the mechanical response of RBCs at the mesoscale.

Atmospheric forcing of coastal polynyas in the south-western Weddell Sea

2015 ◽  
Vol 27 (4) ◽  
pp. 388-402 ◽  
Author(s):  
Verena Haid ◽  
Ralph Timmermann ◽  
Lars Ebner ◽  
Günther Heinemann
Keyword(s):  
Sea Ice ◽  
Large Scale ◽  
Reanalysis Data ◽  
Ocean Model ◽  
Weddell Sea ◽  
Small Scale ◽  
Atmospheric Conditions ◽  
Atmospheric Forcing ◽  
The South ◽  
Ice Production

AbstractThe development of coastal polynyas, areas of enhanced heat flux and sea ice production strongly depend on atmospheric conditions. In Antarctica, measurements are scarce and models are essential for the investigation of polynyas. A robust quantification of polynya exchange processes in simulations relies on a realistic representation of atmospheric conditions in the forcing dataset. The sensitivity of simulated coastal polynyas in the south-western Weddell Sea to the atmospheric forcing is investigated with the Finite-Element Sea ice-Ocean Model (FESOM) using daily NCEP/NCAR reanalysis data (NCEP), 6 hourly Global Model Europe (GME) data and two different hourly datasets from the high-resolution Consortium for Small-Scale Modelling (COSMO) model. Results are compared for April to August in 2007–09. The two coarse-scale datasets often produce the extremes of the data range, while the finer-scale forcings yield results closer to the median. The GME experiment features the strongest winds and, therefore, the greatest polynya activity, especially over the eastern continental shelf. This results in higher volume and export of High Salinity Shelf Water than in the NCEP and COSMO runs. The largest discrepancies between simulations occur for 2008, probably due to differing representations of the ENSO pattern at high southern latitudes. The results suggest that the large-scale wind field is of primary importance for polynya development.

scholarly journals Small-scale sea ice deformation during N-ICE2015: From compact pack ice to marginal ice zone

2017 ◽  
Vol 122 (6) ◽  
pp. 5105-5120 ◽  
Author(s):  
Annu Oikkonen ◽  
Jari Haapala ◽  
Mikko Lensu ◽  
Juha Karvonen ◽  
Polona Itkin
Keyword(s):  
Sea Ice ◽  
Small Scale ◽  
Pack Ice ◽  
Marginal Ice Zone

scholarly journals Flow Visualization of Spinning and Nonspinning Soccer Balls Using Computational Fluid Dynamics

2020 ◽  
Vol 10 (13) ◽  
pp. 4543 ◽  
Author(s):  
Takeshi Asai ◽  
Yasumi Nakanishi ◽  
Nakaba Akiyama ◽  
Sungchan Hong
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Lattice Boltzmann Method ◽  
Vortex Structure ◽  
Lattice Boltzmann ◽  
Large Scale ◽  
Vortex Pair ◽  
Vortex Structures ◽  
Soccer Ball ◽  
Boltzmann Method

Various studies have been conducted on the aerodynamic characteristics of nonspinning and spinning soccer balls. However, the vortex structures in the wake of the balls are almost unknown. One of the main computational fluid dynamics methods used for the analysis of vortex structures is the lattice Boltzmann method as it facilitates high-precision analysis. Studies to elucidate the dominant vortex structure are important because curled shots and passes involving spinning balls are frequently used in actual soccer games. In this study, we identify the large-scale dominant vortex structure of a soccer ball and investigate the stability of the structure using the lattice Boltzmann method, wind tunnel tests, and free-flight experiments. One of the dominant vortex structures in the wake of both nonspinning and spinning balls is a large-scale counter-rotating vortex pair. The side force acting on a spinning ball stabilizes when the fluctuation of the separation points of the ball is suppressed by the rotation of the ball. Thus, although a spinning soccer ball is deflected by the Magnus effect, its trajectory is regular and stable, suggesting that a spinning ball can be aimed accurately at the outset of its course.

scholarly journals The application of computational fluid dynamics and small-scale physical models to assess the effects of operational practices on the risk to public health within large indoor swimming pools

2015 ◽  
Vol 13 (4) ◽  
pp. 939-952 ◽  
Author(s):  
Lowell Lewis ◽  
John Chew ◽  
Iain Woodley ◽  
Jeni Colbourne ◽  
Katherine Pond
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Disease Transmission ◽  
Time Frame ◽  
Physical Models ◽  
Microbial Pathogens ◽  
Small Scale ◽  
Swimming Pools ◽  
Policy Makers ◽  
Operational Practices

Swimming pools provide an excellent facility for exercise and leisure but are also prone to contamination from microbial pathogens. The study modelled a 50-m × 20-m swimming pool using both a small-scale physical model and computational fluid dynamics to investigate how water and pathogens move around a pool in order to identify potential risk spots. Our study revealed a number of lessons for pool operators, designers and policy-makers: disinfection reaches the majority of a full-scale pool in approximately 16 minutes operating at the maximum permissible inlet velocity of 0.5 m/s. This suggests that where a pool is designed to have 15 paired inlets it is capable of distributing disinfectant throughout the water body within an acceptable time frame. However, the study also showed that the exchange rate of water is not uniform across the pool tank and that there is potential for areas of the pool tank to retain contaminated water for significant periods of time. ‘Dead spots’ exist at either end of the pool where pathogens could remain. This is particularly significant if there is a faecal release into the pool by bathers infected with Cryptosporidium parvum, increasing the potential for waterborne disease transmission.

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