Hydrodynamics - Parameters

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Estimation of the Hydrodynamics Coefficients of an ROV using Free Decay Pendulum Motion

Estimation of the Hydrodynamics Coefficients of an ROV using Free Decay Pendulum Motion

In this paper, the hydrodynamics added mass and drag forces will be determined experimentally using a scaled down model (called the scaled model, Fig 1) of the ROV II (called the real model). The scaled model is set to oscillate in water when it is displaced from its equilibrium position and due to the hydrodynamics forces that resist the motion, the amplitude of the swing will decay over time. The hydrodynamics parameters can then be extracted from the time history of the motion. As the scaled model is allowed to oscillate freely in the water tank, the experiment is classified as a free decay test. By applying the laws of Similitude, the hydrodynamics parameters of the scaled model can be scaled up to predict the corresponding values for the full scale vehicle. Then, verification is performed by comparing the experimental values obtained with that predicted by CFD for the full scale ROV.
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Longitudinal hydrodynamics from event-by-event Landau initial conditions

Longitudinal hydrodynamics from event-by-event Landau initial conditions

The viability of the computations performed here depends, of course, on the longitudinal structure of the event really being close to the Landau limit. Because we do not know this from first principles, and given the many undetermined parameters in a typical hydrodynamic simulation, we suggest that exper- imental tests specifically probing boost invariance should be performed. It is intuitively clear that in the Bjorken solution the transverse size of the system, along with other parameters, does not vary with rapidity. It is equally intuitively clear that the strong dependence of flow with rapidity produces a strong rapidity dependence of size at late times. Figure 6 confirms this, where the average r 2  integrated over the transverse radius is shown as a function of rapidity. As can be seen, it approximately follows the Gaussian structure of the transverse momentum characteristic of Landau hydrodynamics [ 27 – 29 ], varying over orders of magnitude in the fragmentation region. In the Bjorken picture, such wide variation is excluded because the transverse size is bounded by the initial transverse size, ∼N 2/3
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Infl uence of mass transfer on bubble plume hydrodynamics

Infl uence of mass transfer on bubble plume hydrodynamics

This paper presents an integral model to evaluate the impact of gas transfer on the hydrodynamics of bubble plumes. The model is based on the Gaussian type self-similarity and functional relationships for the entrainment coeffi cient and factor of momentum amplifi cation due to turbulence. The impact of mass transfer on bubble plume hydrodynamics is investigated considering different bubble sizes, gas fl ow rates and water depths. The results revealed a relevant impact when fi ne bubbles are considered, even for moderate water depths. Additionally, model simulations indicate that for weak bubble plumes (i.e., with relatively low fl ow rates and large depths and slip velocities), both dissolution and turbulence can affect plume hydrodynamics, which demonstrates the importance of taking the momentum amplifi cation factor relationship into account. For deeper water conditions, simulations of bubble dissolution/decompression using the present model and classical models available in the literature resulted in a very good agreement for both aeration and oxygenation processes. Sensitivity analysis showed that the water depth, followed by the bubble size and the fl ow rate are the most important parameters that affect plume hydrodynamics. Lastly, dimensionless correlations are proposed to assess the impact of mass transfer on plume hydrodynamics, including both the aeration and oxygenation modes.
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Numerical Modeling Tools Applied to Estuarine and Coastal Hydrodynamics: A User Perspective

Numerical Modeling Tools Applied to Estuarine and Coastal Hydrodynamics: A User Perspective

Nevertheless, several conclusions about the morpho-hydrodynamic behavior of the Minho estuary can be inferred from previous works. The estuarine processes may be dominated by the river flow or by the tide depending on the magnitude of these two forcing parameters. Extreme river flows can change the circulation pat- tern within the entire estuarine and coastal region, restricting the entrance of oceanic water to the mouth of the estuary. In such cases, the tide acts as a resistance to the fluvial flow. Current velocities of the ebb are higher than the velocity during flood, which produces a higher duration of the ebb. This effect is stronger for low river flows. As expected, currents exhibit higher velocities in the narrower sections, particularly at the mouth of the estuary, but they are also stronger during spring tides than during neap tides. The described hydrodynamic patterns will have a direct effect on sediment transport, which is directly proportional to the strength of the flow and the amplitude of the tide. Similar conclusions were obtained by Iglesias et al. [96] using realistic river flow and tide scenarios. Their numerical solutions show a tide dominated estuary, with a visible tidal effect even for extreme river flows. For low river flow conditions, a large part of the estuarine region is dry, becoming exposed to the wind action. In this situation, river flow is confined to two shallow channels in the estuarine area. During high flow conditions, most of the estuary is flooded, with intense currents throughout the estuarine region, except in the widest part upstream from the river mouth, where the estuary widens and the cross-sectional area increases significantly.
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Higher-order generalized hydrodynamics: foundations within a nonequilibrium statistical ensemble formalism

Higher-order generalized hydrodynamics: foundations within a nonequilibrium statistical ensemble formalism

with the open parameters U and r 0 (r 0 is a length scale playing the role of a range length and U/r 0 being the interaction strength). It has been noticed that this kind of potential belongs to the class of interactions which do not diverge at the origin, i.e., are bounded. They are potentials corresponding to effective interactions between the centers of mass of soft, flexible macromolecules such as polymer chains [ 57 ], dendrimers [ 58 ], and others. The centers of mass of two macromolecules can coincide without violation of the excluded volume conditions, hence implying a bounded interaction [ 59 ]. Several studies of this potential can be consulted, for example, in Refs. [ 60 – 63 ].
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Wave hydrodynamics in coastal stretches influenced by detached breakwaters

Wave hydrodynamics in coastal stretches influenced by detached breakwaters

Bárbara Vasquez Vieira 59 and average time periods, peak and average directions, directional dispersion, parameter of bandwidth and level of water anywhere in the computational domain (Capitão and Fortes, 2011). Most applications of this model to the Portuguese coast has been carried out in operational forecasting systems of waves, Rusu and Guedes Soares (2008a, 2008b) and Silva et al. (2009), for example. There are several studies of performance analysis SWAN model when applied to the Portuguese coast, such as those resulting from its application to the maritime area of Pinheiro da Cruz, [Pires – Silva et al. (2002); Teles et al. (2009)], or the Alfeite beach [Santos et al. (2007); Capitão et al. (2009) and Rusu et al. (2009, 2011)], in which field measurements were made, or to situations in which they had data buoy such as the maritime area of the port of Sines and Faro Leixões [Capitão et al. (2006); Rusu et al. (2005a, 2005b, 2008b) and Silva et al. (2009)], or parts of the Madeira archipelago [Rusu et al. (2008a)], and the Azores archipelago, in the maritime area of the Port of Victoria Beach [Guilherme et al. (2009); Santos et al. (2009)]. In all these studies, the establishment of the conditions of application of the model as well as the calibration of its parameters is strongly conditioned by place of study, and hence the accuracy of the model depends on these conditions and other parameters.
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Nunerical modelling of groin impact on nearshore hydrodynamics

Nunerical modelling of groin impact on nearshore hydrodynamics

It is important to note that the field values of velocity are measured near the surface, and the numerical values are calculated at a depth, which is located approximately at water- column mid-depth. This could help explaining some of the differences between field and numerical data. Also, the values of velocity measured and simulated during lower water-level periods tend to present unrealistically higher values, as the ECM is emerged. These values were excluded from analysis (the same number for both components and the same number for both field and numerical data in the calculation of the statistical parameters), although some values in the beginning and the end of each of the five intervals considered for analysis are still biased due to the progressive emersion of the ECM. Hence, the calculation of the values of BIAS, RMSE and d implied the exclusion of several values, which reduced the size of the sample and tends to mask the real values of these statistical parameters, which should thus be considered with care.
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BEHAVIOR OF STRESSES AND HYDRODYNAMICS FROM MULTICOMPONENT SEISMIC DATA

BEHAVIOR OF STRESSES AND HYDRODYNAMICS FROM MULTICOMPONENT SEISMIC DATA

The key stress parameters of a section discontinuity (namely, overburden pressure, normal components of horizontal stress, intensity of tangential stress), for horizontal and non-horizon[r]

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Measuring hydrodynamics and sediment transport processes in the Dee Estuary

Measuring hydrodynamics and sediment transport processes in the Dee Estuary

due to its position in reference to the central part of the chan- nel. Wave parameters are modulated by tide. The wave event during the second neap period, observed in the Welsh chan- nel, is not present in the Hilbre channel due to a possible dissipation of energy when waves propagate in the estuary mouth. Current direction (not shown) at the Hilbre channel location is aligned with N-S while at the Welsh channel is E-W. The ebbs at the Welsh channel produce a change in cur- rent direction that could be attributed to eddy formation due to curvature of channel, interaction with the fame and with the coastline ledge. Wave direction is predominantly from E and NE at the Welsh channel, however at the Hilbre predomi- nant directions are from north, in agreement with the channel orientation. Mean periods in the area range from 3–6 s and peak period from 4–10 s.
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Dissipative hydrodynamics coupled to chiral fields

Dissipative hydrodynamics coupled to chiral fields

Assuming the validity of a relativistic viscous hydro- dynamical description, experimental extraction of transport coefficients should be possible in principle from comparison with measured momentum anisotropy patterns. Moreover, as suggested in Ref. [31], such a comparison with experimental data would allow one to pinpoint the location of the QCD phase transition or of a crossover from hadronic to quark-gluon matter. In this context, in addition to the hydrodynamic degrees of freedom related to energy-momentum conservation, degrees of freedom associated with order parameters of broken continuous symmetries must be considered as well because they are all coupled to each other. Particularly important to the
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Fluctuation effects in initial conditions for hydrodynamics

Fluctuation effects in initial conditions for hydrodynamics

II. FLUCTUATIONS IN THE INITIAL CONDITIONS One of the present problems which high-energy nuclear and hadronic collisions are faced with is the determination of the energy deposited in the reaction or, equivalently, the fraction k of the total incident energy A s consumed to pro- duce particles. As mentioned in the Introduction, this frac- tion, or inelasticity, is an essential ingredient for statistical models of high-energy hadronic collisions. We apply the IGM to calculate this quantity. The main reason for this is that, in terms of few parameters, it allows us to obtain ana- lytically the inelasticity distribution as a function of the in- cident energy; this, in its turn, is immediately related to the leading-particle spectrum. Another reason would be a very good agreement with the existing data on both these quanti- ties, as will be seen in this section with our formulation of IGM.
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Nonlinear causality of general first-order relativistic viscous hydrodynamics

Nonlinear causality of general first-order relativistic viscous hydrodynamics

3 ≥ 0. Note that in Ref. [52] the stability conditions for the boosted frame have been verified only for the first and second lowest orders in k for the dispersion relation ωðkÞ for the sound waves perpendicular to v i , which does not demand any new condition besides (10) . In this sense, the conditions coming from the homogeneous frame are essential and make a direct link between linear stability and nonlinear causality. In the non-homogeneous case with v i ≠ 0, one is left with a very complex polynomial that cannot be analyzed analytically. In this case we can still carry out the stability analysis numerically, and we did verified stability for several possible choices of parameters. An extensive numerical study of stability, however, is beyond the scope of the present work and we believe that it is better to investigate stability on a case-by-case basis, where one already has a pre-determined range of parameter values relevant for specific applications.
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Uma análise comparativa de métodos aproximativos baseados em smoothed particle hydrodynamics para animação de fluidos

Uma análise comparativa de métodos aproximativos baseados em smoothed particle hydrodynamics para animação de fluidos

Animações de fluidos, como a água ou fumaça, são utilizadas para introduzir detalhes em jogos virtuais ou filmes. Vários métodos existem para a simulação de fluidos utilizando sistemas de partículas e, em especial, utilizando o método Smoothed Particle Hydrodynamics, ou SPH. O método SPH é uma boa escolha para a simulação de fluidos por sua fácil descrição e implemen- tação. Este trabalho apresenta alguns métodos baseados no SPH para a simulação de fluidos gerais, e para a interação entre fluidos e sólidos. Esses métodos são analisados e compara- dos relativos ao seu realismo, apresentando alguns pontos fracos de cada método. Essa análise pode ser utilizada para guiar a implementação de melhores métodos baseados no SPH, e para a animação realista de fluidos.
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Smoothed particle hydrodynamics modelling in continuum mechanics: fluid-structure interaction

Smoothed particle hydrodynamics modelling in continuum mechanics: fluid-structure interaction

Within this study, the implementation of the smoothed particle hydrodynamics (SPH) method solving the complex problem of interaction between a quasi-incompressible fluid involving a free surface and an elastic structure is out- lined. A brief description of the SPH model for both the quasi-incompressible fluid and the isotropic elastic solid is presented. The interaction between the fluid and the elastic structure is realised through the contact algorithm. The results of numerical computations are confronted with the experimental as well as computational data published in the literature.
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Aplicação do método lagrangiano SPH (Smoothed Particle Hydrodynamics ) para a solução do problema das cavidades

Aplicação do método lagrangiano SPH (Smoothed Particle Hydrodynamics ) para a solução do problema das cavidades

O método lagrangiano sem malhas SPH (Smoothed Particles Hydrodynamics) foi proposto inicialmente em 1977, por Leon Lucy e por Gingold e Monaghan, e se tangenciou na solução de problemas astrofísicos, implementando o método para estudo de colisões entre as estrelas, formação de galáxias e supernovas, propondo uma formulação mais simples e baseada em partículas, tendo como característica, a substituição do fluido por um conjunto finito de partículas. No método numérico SPH não há necessidade de serem geradas malhas, a discretização é realizada sob uma quantidade finita de partículas e é desenvolvida sob uma teoria da interpolação de dados, sendo esse um dos fundamentos.
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Morphological Patterns of Fish and Their Relationships with Reservoirs Hydrodynamics

Morphological Patterns of Fish and Their Relationships with Reservoirs Hydrodynamics

However, many species do not have adaptations that allow them to inhabit lentic environments, and may be locally extinct (Lowe-McConnell, 1975). According to Sagnes et al. (2000) and Wikramanayake (1990), other factors are involved in fish habitat selection; however, the study of body hydrodynamics and swimming ability of fish species has a promising perspective for the understanding and prediction of relationships between habitat use and water flow.

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Parameters Results PBS Ethanol

Parameters Results PBS Ethanol

Flurbiprofen (FLB), a NSAID, widely used for preventing pain generally for arthritis or dental problems. In this study, FLB loaded chitosan microspheres were prepared by ionotropic gelation method. In this method, microspheres were formed by dropping chitosan solutions containing FLB into sodium alginate solutions including sodium tripolyphosphate (TPP). A variety of formulation parameters like drug:polymer ratio, drug concentration, polymer’s molecular weight, polymer concentration, pH and the concentration of TPP solutions, drying method and stirring time were analyzed. The dissolution studies were performed in a shaking water bath in pH 7.4 phosphate buffer saline (PBS) at 37 °C. Laser diffractometer was used for particle size analysis, and scanning electron microscope (SEM) was used for morphological properties. Drug loading and loading efficiency were calculated by using UV spectrophotometer. The particles obtained were spherical with 0.7-1.3 mm size range, and the loading efficiency was approximately 21-79%. The dissolution studies conducted revealed that drug:polimer ratio and the polymer type and concentration affected the drug release from microspheres. It was observed that increasing the polymer concentration, polymer’s molecular weight and TPP concentration decreased the FLB release from microspheres, which was according to Higuchi kinetics.
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Consistent temperature coupling with thermal fluctuations of smooth particle hydrodynamics and molecular dynamics.

Consistent temperature coupling with thermal fluctuations of smooth particle hydrodynamics and molecular dynamics.

We propose a thermodynamically consistent and energy-conserving temperature coupling scheme between the atomistic and the continuum domain. The coupling scheme links the two domains using the DPDE (Dissipative Particle Dynamics at constant Energy) thermostat and is designed to handle strong temperature gradients across the atomistic/continuum domain interface. The fundamentally different definitions of temperature in the continuum and atomistic domain – internal energy and heat capacity versus particle velocity – are accounted for in a straightforward and conceptually intuitive way by the DPDE thermostat. We verify the here-proposed scheme using a fluid, which is simultaneously represented as a continuum using Smooth Particle Hydrodynamics, and as an atomistically resolved liquid using Molecular Dynamics. In the case of equilibrium contact between both domains, we show that the correct microscopic equilibrium properties of the atomistic fluid are obtained. As an example of a strong non-equilibrium situation, we consider the propagation of a steady shock-wave from the continuum domain into the atomistic domain, and show that the coupling scheme conserves both energy and shock-wave dynamics. To demonstrate the applicability of our scheme to real systems, we consider shock loading of a phospholipid bilayer immersed in water in a multi-scale simulation, an interesting topic of biological relevance.
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Discrete effects on the forcing term for the lattice Boltzmann modeling of steady hydrodynamics

Discrete effects on the forcing term for the lattice Boltzmann modeling of steady hydrodynamics

The lattice Boltzmann method (LBM) [1–3] is a well estab- lished numerical technique to solve the Navier-Stokes equations (NSE). Despite its many inherent advantages, cf. the review arti- cles [4,5] and the monographes [6,7] , the crucial step to bridge the link between the mesoscopic LBM formulation and the spe- cific hydrodynamics variables still presents some challenges. For the “athermal” LBM, such a consistency link is expressed by the simultaneous satisfaction of the following two points: (i) the LBM first three velocity moments should match the required hydrody- namic expressions and (ii) no numerical artifacts should be intro- duced during the discretisation process.
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