scholarly journals Improving the Accuracy of Hydrodynamic Model Predictions Using Lagrangian Calibration

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 575 ◽  
Author(s):  
Neda Mardani ◽  
Kabir Suara ◽  
Helen Fairweather ◽  
Richard Brown ◽  
Adrian McCallum ◽  
...  
Keyword(s):  
Hydrodynamic Model ◽  
Field Measurements ◽  
Hydrodynamic Models ◽  
Lagrangian Drifters ◽  
Lagrangian Velocity ◽  
Model Predictions ◽  
Spatio Temporal ◽  
Lagrangian Data ◽  
Lagrangian Drifter ◽  
Recent Attention

While significant studies have been conducted in Intermittently Closed and Open Lakes and Lagoons (ICOLLs), very few have employed Lagrangian drifters. With recent attention on the use of GPS-tracked Lagrangian drifters to study the hydrodynamics of estuaries, there is a need to assess the potential for calibrating models using Lagrangian drifter data. Here, we calibrated and validated a hydrodynamic model in Currimundi Lake, Australia using both Eulerian and Lagrangian velocity field measurements in an open entrance condition. The results showed that there was a higher level of correlation (R2 = 0.94) between model output and observed velocity data for the Eulerian calibration compared to that of Lagrangian calibration (R2 = 0.56). This lack of correlation between model and Lagrangian data is a result of apparent difficulties in the use of Lagrangian data in Eulerian (fixed-mesh) hydrodynamic models. Furthermore, Eulerian and Lagrangian devices systematically observe different spatio-temporal scales in the flow with larger variability in the Lagrangian data. Despite these, the results show that Lagrangian calibration resulted in optimum Manning coefficients (n = 0.023) equivalent to those observed through Eulerian calibration. Therefore, Lagrangian data has the potential to be used in hydrodynamic model calibration in such aquatic systems.

scholarly journals Lagrangian Data Assimilation for Improving Model Estimates of Velocity Fields and Residual Currents in a Tidal Estuary

2021 ◽  
Vol 11 (22) ◽  
pp. 11006
Author(s):  
Neda Mardani ◽  
Mohammadreza Khanarmuei ◽  
Kabir Suara ◽  
Richard Brown ◽  
Adrian McCallum ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Hydrodynamic Model ◽  
Numerical Models ◽  
Low Cost ◽  
Velocity Fields ◽  
Moving Frame ◽  
Residual Currents ◽  
Lagrangian Data ◽  
Flow Variables ◽  
Lagrangian Drifter

Numerical models are associated with uncertainties that can be reduced through data assimilation (DA). Lower costs have driven a recent tendency to use Lagrangian instruments such as drifters and floats to obtain information about water bodies. However, difficulties emerge in their assimilation, since Lagrangian data are set out in a moving frame of reference and are not compatible with the fixed grid locations used in models to predict flow variables. We applied a pseudo-Lagrangian approach using OpenDA, an open-source DA tool to assimilate Lagrangian drifter data into an estuarine hydrodynamic model. Despite inherent challenges with using drifter datasets, the work showed that low-cost, low-resolution drifters can provide a relatively higher improvement over the Eulerian dataset due to the larger area coverage of the drifter. We showed that the assimilation of Lagrangian data obtained from GPS-tracked drifters in a tidal channel for a few hours can significantly improve modelled velocity fields (up to 30% herein). A 40% improvement in residual current direction was obtained when assimilating both Lagrangian and Eulerian data. We conclude that the best results are achieved when both Lagrangian and Eulerian datasets are assimilated into the hydrodynamic model.

POD Analysis of the Impact Dynamics of the Olive Tree Branch: Nature’s Paradigm of a Complex Soft-Stiff Structural System in Biomechanics

2017 ◽  
Author(s):  
Ioannis T. Georgiou
Keyword(s):  
Nonlinear Vibrations ◽  
Field Measurements ◽  
Olive Tree ◽  
Structural System ◽  
Impulsive Forces ◽  
Spatio Temporal ◽  
Pod Analysis ◽  
Complete Detachment ◽  
Tree Branch ◽  
The Impact

Geometry consistent spatio-temporal measurements of the experimental acceleration of olive tree branches were analyzed with advanced POD tools in an effort to gain knowledge on the mechanics-dynamics of this bio-mechanical structure. To pave the way for understanding the dynamics of this system, both the typical olive tree as a whole and its typical branch are approached as interacting soft-stiff continuum mechanical systems. The POD analysis reveals that the impact response is a nonlinear vibration with very fast dissipation. The POD modal amplitudes are nonlinear vibrations of continuous, broadband frequency spectrum. Initially they exhibit regular phases of nonlinear slow dissipation-and-amplification followed by irregular, fast dissipation-and-amplification phases. Sequentially applied impacts at the branch soft area results in a complete detachment of the fruit. The POD analysis reveals that this occurs because the response is highly localized in the soft area where the impact is applied and thus it transfers its momentum to the fruits. The work is supplemented with analysis of field measurements of the acceleration dynamics of orchard olive tree branches excited by harvesting devices generating combing clouds of impulsive forces aimed at detaching the olive fruit by momentum transfer.

Equations of Hydrodynamics, Heat, and Mass Transfer in Models of Regional and Mesoscale Atmospheric Processes

2017 ◽  
pp. 169-197
Keyword(s):  
Mass Transfer ◽  
Mathematical Models ◽  
Heat And Mass Transfer ◽  
Hydrodynamic Model ◽  
Specific Area ◽  
Hydrodynamic Models ◽  
Atmospheric Processes

The formation of meteorological processes and phenomena in the atmosphere in each specific area is influenced by the processes of different scales. However, the significance of each process in different cases is different. Therefore, there are certain priorities for the inclusion of certain processes in the hydrodynamic model. Depending on the size of the territory taken for modeling of processes or individual phenomena in the atmosphere, hydrodynamic models are divided into local and regional. In this chapter, we consider these features in terms of mathematical models.

scholarly journals Automating the creation of channel cross section data from aerial laser scanning and hydrological surveying for modeling flood events / Automatická tvorba geometrie vodních toků na základě syntézy dat z leteckého laserového skenování a hydrologického měření pro modelování povodňových událostí. j. hydrol., hydromech., 60, 2012, 4; 25 lit., 8 obr., 5 tab.

2012 ◽  
Vol 60 (4) ◽  
pp. 227-241 ◽  
Author(s):  
Radek Roub ◽  
Tomáš Hejduk ◽  
Pavel Novák
Keyword(s):  
Flow Rate ◽  
Hydrodynamic Model ◽  
Input Data ◽  
Laser Scanning ◽  
Digital Terrain Model ◽  
Flood Events ◽  
Hydrodynamic Models ◽  
Terrain Model ◽  
Aerial Laser Scanning ◽  
Digital Terrain

Knowing the extent of inundation areas for individual N-year flood events, the specific flood scenarios, and having an idea about the depths and velocities in the longitudinal or transverse water course profile provided by hydrodynamic models is of key importance for protecting peoples’ lives and mitigating damage to property. Input data for creating the watercourse computational geometry are crucial for hydrodynamic models. Requirements for input data vary with respect to the hydrodynamic model used. One-dimensional (1D) hydrodynamic models in which the computing track is formed by cross-sectional profiles of the channel are characterized by lower requirements for input data. In two-dimensional (2D) hydrodynamic models, a digital terrain model is needed for the entire area studied. Financial requirements of the project increase with regard to the input data and the model used. The increase is mainly due to the high cost of the geodetic surveying of the stream channel. The paper aims at a verification and presentation of the suitability of using hydrological measurements in developing a schematization (geometry) of water courses based on topographic data gained from aerial laser scanning provided by the Czech Office for Surveying, Mapping and Cadastre. Taking into account the hydrological measurement during the schematization of the water course into the hydrodynamic model consists in the derivation of flow rate achieved at the time of data acquisition using the method of aerial laser scanning by means of hydrological analogy and in using the established flow rate values as a basis for deepening of the digital terrain model from aerial laser scanning data. Thus, the given principle helps to capture precisely the remaining part of the channel profile which is not reflected in the digital terrain model prepared by the method of aerial laser scanning and fully correct geometry is achieved for the hydrodynamic model.

scholarly journals Models for X-ray Emission from Tycho’s Remnant

1988 ◽  
Vol 101 ◽  
pp. 133-136
Author(s):  
Barham W. Smith ◽  
Eric M. Jones
Keyword(s):  
Spectral Data ◽  
Hydrodynamic Model ◽  
Thermal Conduction ◽  
Spherically Symmetric ◽  
Hydrodynamic Models ◽  
X Ray ◽  
Emission Properties ◽  
Circumstellar Medium

AbstractWe reexamine the X-ray emission from Tycho’s remnant using results from hydrodynamic models computed with a detailed spherically symmetric code. The observed synchrotron radio contours (Green and Gull 1983) appear to require a cloudy circumstellar medium (Dickel and Jones, 1985; Dickel, Eilek, and Jones 1987), thus we explore the X-ray emission properties of similar models. We find that they tend to produce broad shells of X-ray emission that resemble the observed X-ray map of Tycho (Seward, Gorenstein, and Tucker 1983). A simple hydrodynamic model can satisfy both radio and X-ray observations, but it has little similarity to the evolution of remnants in cloudy media dominated by thermal conduction (McKee and Ostriker 1977). More work needs to be done to ensure that the spectrum as well as the X-ray map can be modeled with the same cloudy circumstellar medium, although we believe it will not be difficult to obtain as good a statistical agreement with the spectral data as other models have achieved (e.g. Hamilton, Sarazin, and Szymkowiak 1986).

scholarly journals Tidal current energy potential of Nalón river estuary assessment using a high precision flow model

2018 ◽  
Vol 8 (1) ◽  
pp. 118-123
Author(s):  
Nicolás Badano ◽  
Rodolfo Espina Valdés ◽  
Eduardo Álvarez Álvarez
Keyword(s):  
High Precision ◽  
Hydrodynamic Model ◽  
Tidal Current ◽  
Flow Model ◽  
River Estuary ◽  
River Mouth ◽  
Hydrodynamic Models ◽  
Energy Potential ◽  
Tidal Current Energy ◽  
Current Energy

Abstract Obtaining energy from tide currents in onshore locations is of great interest due to the proximity to the points of consumption. This opens the door to the feasibility of new installations based on hydrokinetic microturbines even in zones of moderate speed. In this context, the accuracy of energy predictions based on hydrodynamic models is of paramount importance. This research presents a high precision methodology based on a multidimensional hydrodynamic model that is used to study the energetic potential in estuaries. Moreover, it is able to estimate the flow variations caused by microturbine installations. The paper also shows the results obtained from the application of the methodology in a study of the Nalón river mouth (Asturias, Spain).

scholarly journals Comparison of Non-Parabolic Hydrodynamic Models Based On Different Band Structure Models

VLSI Design ◽  
1998 ◽  
Vol 6 (1-4) ◽  
pp. 177-180
Author(s):  
Arlynn W. Smith ◽  
Kevin F. Brennan
Keyword(s):  
Dispersion Relation ◽  
Band Structure ◽  
Energy Range ◽  
Closed Form ◽  
Power Law ◽  
Hydrodynamic Model ◽  
Wide Energy Range ◽  
Hydrodynamic Models ◽  
Wide Energy ◽  
Extended Power

This paper presents two non-parabolic hydrodynamic model formulations suitable for the simulation of inhomogeneous semiconductor devices. The first formulation uses the Kane dispersion relationship, (ℏk)2/2m = W(1+αW). The second formulation makes use of a power law, (ℏk)2/2m = xWy, for the dispersion relation. The non-parabolicity and energy range of the hydrodynamic model based on the Kane dispersion relation is limited. The power law formulation produces closed form coefficients similar to those under the parabolic band approximation but the carrier concentration can deviate. An extended power law dispersion relation is proposed to account for band structure effects, (ℏk)2/2m = xW1+yW. This dispersion relation closely matches the calculated band structure over a wide energy range and may lead to closed form coefficients for the hydrodynamic model.

scholarly journals Coded continuous wave meteor radar

2015 ◽  
Vol 8 (7) ◽  
pp. 7879-7907
Author(s):  
J. Vierinen ◽  
J. L. Chau ◽  
N. Pfeffer ◽  
M. Clahsen ◽  
G. Stober
Keyword(s):  
Temporal Resolution ◽  
Large Scale ◽  
Pulse Compression ◽  
Continuous Wave ◽  
Signal To Noise Ratio ◽  
Field Measurements ◽  
Meteor Radar ◽  
Spatio Temporal ◽  
To Receive ◽  
Pulse Spacing

Abstract. The concept of coded continuous wave meteor radar is introduced. The radar uses a continuously transmitted pseudo-random waveform, which has several advantages: coding avoids range aliased echoes, which are often seen with commonly used pulsed specular meteor radars (SMRs); continuous transmissions maximize pulse compression gain, allowing operation with significantly lower peak transmit power; the temporal resolution can be changed after performing a measurement, as it does not depend on pulse spacing; and the low signal to noise ratio allows multiple geographically separated transmitters to be used in the same frequency band without significantly interfering with each other. The latter allows the same receiver antennas to be used to receive multiple transmitters. The principles of the signal processing are discussed, in addition to discussion of several practical ways to increase computation speed, and how to optimally detect meteor echoes. Measurements from a campaign performed with a coded continuous wave SMR are shown and compared with two standard pulsed SMR measurements. The type of meteor radar described in this paper would be suited for use in a large scale multi-static network of meteor radar transmitters and receivers. This would, for example, provide higher spatio-temporal resolution for mesospheric wind field measurements.

scholarly journals Application and Verification of a three-dimensional Hydrodynamic Model to Hamilton Harbour, Canada

2013 ◽  
Vol 2 (1) ◽  
pp. 77-89
Keyword(s):  
Water Level ◽  
Hydrodynamic Model ◽  
Three Dimensional ◽  
Model Verification ◽  
Water Current ◽  
Trajectory Model ◽  
Hamilton Harbour ◽  
Water Level Changes ◽  
Model Predictions ◽  
Good Agreement

A multi-layered three-dimensional hydrodynamic model has been developed to provide flow fields and water level changes in Hamilton Harbour. The field data collected in Hamilton Harbour during 1990 & 1991 field seasons was used for model verification. The simulated currents were compared with current meter data. Results from the trajectory model are in good agreement with the drogue experimental data. A quantitative criterion to evaluate the trajectory comparison was established with the help of the trajectory model using the random-walk approach. By using the water level changes in the Burlington Ship Canal, the model predictions were validated with the measurements at three water level stations in the Harbour. These comparisons demonstrate that the models can simulate the major features of the water current and level changes in Hamilton Harbour.

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