scholarly journals INTERACTIVE AND IMMERSIVE COASTAL HYDRODYNAMIC SIMULATION

2018 ◽  
pp. 63
Author(s):  
Patrick J. Lynett ◽  
Sasan Tavakkol
Keyword(s):  
Open Access ◽  
Boundary Conditions ◽  
Wave Model ◽  
Water Velocity ◽  
Model Parameters ◽  
Wave Interactions ◽  
Hydrodynamic Simulation ◽  
Wave Dynamics ◽  
Physical Variables ◽  
Language Environment

In this presentation, we will discuss the development and application of a GPU-based Boussinesq-type wave model. The novelty of this approach is that it is meant to serve the primary purpose of being interactive – allowing the user to modify the boundary conditions and model parameters as the model is running, and to see the effect of these changes immediately. To accomplish this, the model is coded in a shader language environment, and our physical variables (e.g. ocean surface elevation, water velocity) are represented in the model as textures, which can be rapidly rendered and visualized via a GPU. This software can help scientists better understand nearshore wave dynamics as it allows them to observe wave interactions in real-time and modify the boundary conditions and model parameters as the model is running to see the effect of these changes immediately. The model is named “Celeris”, and is released under the GNU (open-source, open-access) license.

scholarly journals OPPORTUNITIES FOR INTERACTIVE, PHYSICS-DRIVEN WAVE SIMULATION USING THE BOUSSINESQ-TYPE MODEL, CELERIS

2017 ◽  
pp. 11
Author(s):  
Sasan Tavakkol ◽  
Patrick Lynett
Keyword(s):  
Boundary Conditions ◽  
Wave Model ◽  
Simulation Software ◽  
Irregular Waves ◽  
Type Model ◽  
Model Parameters ◽  
Breaking Wave ◽  
Wave Simulation ◽  
Recent Developments ◽  
Language Environment

In this paper, we discuss the recent developments of our GPU-based Boussinesq-type wave simulation software, Celeris. This software is meant to serve the primary purpose of being interactive – i.e. allowing the user to modify the boundary conditions and model parameters as the model is running, and to see the effect of these changes immediately. To accomplish this, the model is coded in a shader language environment, and our physical variables (e.g. ocean surface elevation, water velocity) are represented in the model as graphical textures, which can therefore be rapidly rendered and visualized via a GPU. The model may run faster than real-time for problems with practical setups. Following a description of the numerical development of the wave model, we elaborate on the recent features that are added to the software such as irregular waves and uniform time series boundary conditions. Since the model is previously validated for breaking and non-breaking wave, in this paper, we compare the numerical results of the model with experimental results of a current benchmark and show its good agreement.

On the Importance of the Exact Nonlinear Interactions in the Spectral Characterization of Rogue Waves

2018 ◽  
Author(s):  
Sonia Ponce de León ◽  
Alfred R. Osborne ◽  
Carlos Guedes Soares
Keyword(s):  
Wave Spectrum ◽  
Wave Model ◽  
Rogue Waves ◽  
Clear Understanding ◽  
Nonlinear Interactions ◽  
Wave Interactions ◽  
Nonlinear Part ◽  
Wave Dynamics ◽  
Spectral Wave Model ◽  
Future Work

This work is focused on the analysis of the wave action equation with full 4-wave interactions (Snl4). For this purpose, we have applied a state-of-the-art spectral wave model (Wave Watch III), using an exact method for the calculation of the full nonlinear Boltzmann interactions in the evolution of the wave spectrum. We emphasize the use of the exact WRT method [Van Vledder, 2006] for the computation of the Snl4 interactions instead of the approximate DIA method. The WRT algorithm includes the full Boltzmann integrations. We discuss how the WRT method is important in any assessment of rogue waves in the ocean and discuss how the enhanced spectral peak assists the formation of rogue waves packets. We demonstrate how the most nonlinear part of the peak of the spectrum is reduced in amplitude when the nonlinear interactions are instead computed using the DIA interactions. These results suggest that a clear understanding of the physics of nonlinear interactions and of rogue wave dynamics requires the use of the full Boltzmann interactions. Future work would include faster WRT computations so that practical forecasting/hindcasting can become possible using the full four-wave interactions.

Model of vortex flow of charge in a vessel with turbine impeller

1987 ◽  
Vol 52 (8) ◽  
pp. 1888-1904
Author(s):  
Miloslav Hošťálek ◽  
Ivan Fořt
Keyword(s):  
Boundary Conditions ◽  
Equations Of Motion ◽  
Theoretical Data ◽  
Eddy Diffusion ◽  
Quantitative Agreement ◽  
Creeping Flow ◽  
Model Parameters ◽  
Mean Flow ◽  
Two Dimensional Flow ◽  
Vorticity Transport

A theoretical model is described of the mean two-dimensional flow of homogeneous charge in a flat-bottomed cylindrical tank with radial baffles and six-blade turbine disc impeller. The model starts from the concept of vorticity transport in the bulk of vortex liquid flow through the mechanism of eddy diffusion characterized by a constant value of turbulent (eddy) viscosity. The result of solution of the equation which is analogous to the Stokes simplification of equations of motion for creeping flow is the description of field of the stream function and of the axial and radial velocity components of mean flow in the whole charge. The results of modelling are compared with the experimental and theoretical data published by different authors, a good qualitative and quantitative agreement being stated. Advantage of the model proposed is a very simple schematization of the system volume necessary to introduce the boundary conditions (only the parts above the impeller plane of symmetry and below it are distinguished), the explicit character of the model with respect to the model parameters (model lucidity, low demands on the capacity of computer), and, in the end, the possibility to modify the given model by changing boundary conditions even for another agitating set-up with radially-axial character of flow.

Updating Substructure Models With Dynamic Boundary Conditions

1995 ◽  
Author(s):  
Michael Link ◽  
Zheng Qian
Keyword(s):  
Boundary Conditions ◽  
Dynamic Stiffness ◽  
Design Parameters ◽  
Physical Parameters ◽  
Model Parameters ◽  
Dynamic Boundary Conditions ◽  
Main Structure ◽  
Modal Data ◽  
Residual Structure ◽  
Dynamic Boundary

Abstract In recent years procedures for updating analytical model parameters have been developed by minimizing differences between analytical and preferably experimental modal analysis results. Provided that the initial analysis model contains parameters capable of describing possible damage these techniques could also be used for damage detection. In this case the parameters are updated using test data before and after the damage. Looking at complex structures with hundreds of parameters one generally has to measure the modal data at many locations and try to reduce the number of unknown parameters by some kind of localization technique because the measurement information is generally not sufficient to identify all the parameters equally distributed all over the structure. Another way of reducing the number of parameters shall be presented here. This method is based on the idea of measuring only a part of the structure and replacing the residual structure by dynamic boundary conditions which describe the dynamic stiffness at the interfaces between the measured main structure and the remaining unmeasured residual structure. This approach has some advantage since testing could be concentrated on critical areas where structural modifications are expected either due to damage or due to intended design changes. The dynamic boundary conditions are expressed in Craig-Bampton (CB) format by transforming the mass and stiffness matrices of the unmeasured residual structure to the interface degrees of freedom (DOF) and to the modal DOFs of the residual structure fixed at the interface. The dynamic boundary stiffness concentrates all physical parameters of the residual structure in only a few parameters which are open for updating. In this approach damage or modelling errors within the unmeasured residual structure are taken into account only in a global sense whereas the measured main structure is parametrized locally as usual by factoring mass and stiffness submatrices defining the type and the location of the physical parameters to be identified. The procedure was applied to identify the design parameters of a beam type frame structure with bolted joints using experimental modal data.

scholarly journals COMPARATIVE ANALYSIS OF DIFFERENT CAD METHODS FOR EXTRACTION OF THE HEMT NOISE WAVE MODEL PARAMETERS

2017 ◽  
Vol 16 (2) ◽  
pp. 117
Author(s):  
Vladica Đorđević ◽  
Zlatica Marinković ◽  
Olivera Pronić-Rančić
Keyword(s):  
Comparative Analysis ◽  
Electron Mobility ◽  
Computer Aided Design ◽  
Wave Model ◽  
High Electron Mobility Transistor ◽  
Extraction Methods ◽  
Model Parameters ◽  
High Electron ◽  
High Electron Mobility ◽  
Noise Modeling

The noise wave model has appeared as a very appropriate model for the purpose of transistor noise modeling at microwave frequencies. The transistor noise wave model parameters are usually extracted from the measured transistor noise parameters by using time-consuming optimization procedures in microwave circuit simulators. Therefore, three different Computer-Aided Design methods that enable more efficient automatic determination of these parameters in the case of high electron-mobility transistors were developed. All of these extraction methods are based on different noise de-embedding procedures, which are described in detail within this paper. In order to validate the presented extraction methods, they were applied for the noise modeling of a specific GaAs high electron-mobility transistor. Finally, the obtained results were used for the comparative analysis of the presented extraction approaches in terms of accuracy, complexity and effectiveness.

The recent upgrade of CMEMS MEDWAVES wave system: description and evaluation.

2021 ◽  
Author(s):  
Michalis Ravdas ◽  
Anna Zacharioudaki ◽  
Gerasimos Korres
Keyword(s):  
Product Quality ◽  
Wave Model ◽  
Wave System ◽  
System Description ◽  
Wave Dynamics ◽  
High Resolution Analysis ◽  
Resolution Analysis ◽  
The Mediterranean ◽  
Sea Area ◽  
Environment Service

<p>The Med-waves system has been implemented in the framework of the Mediterranean component (MED MFC) of the Copernicus Marine Environment Service (CMEMS) and generates high-resolution analysis, forecast, and reanalysis wave products for the Mediterranean Sea area. The system which is based on the WAM wave model is operational since 2017 and is continuously upgraded in order to represent better the Mediterranean wave dynamics with a high forecast skill. The purpose of this work is to present a description of the various improvements introduced to the system and their impact on the wave product quality. The validation of the system which is done by comparing the model output against buoys and satellite altimeters measurements shows the product quality changes (improvements) due to the different upgrades of the Med-waves system. Based on this upgraded system, we will also give the detailed characteristics of the new reanalysis wave product which is driven by atmospheric forcing from ECMWF ERA5 and provides hourly wave parameters from 1993.</p>

scholarly journals An analytical model for soil-atmosphere feedback

2012 ◽  
Vol 16 (7) ◽  
pp. 1863-1878 ◽  
Author(s):  
B. Schaefli ◽  
R. J. van der Ent ◽  
R. Woods ◽  
H. H. G. Savenije
Keyword(s):  
Soil Moisture ◽  
Boundary Conditions ◽  
Hydrological Cycle ◽  
Analytical Framework ◽  
Model Parameters ◽  
Nonlinear Relationship ◽  
Atmospheric Moisture ◽  
Functional Relationships ◽  
Soil Atmosphere ◽  
Potential System

Abstract. Soil-atmosphere feedback is a key for understanding the hydrological cycle and the direction of potential system changes. This paper presents an analytical framework to study the interplay between soil and atmospheric moisture, using as input only the boundary conditions at the upstream end of trajectory, assuming advective moisture transport with average wind speed along this trajectory and vertical moisture exchange with the soil compartment of uniform vertical properties. Precipitation, evaporation from interception and runoff are assumed to depend through simple functional relationships on the soil moisture or the atmospheric moisture. Evaporation from soil moisture (including transpiration) depends on both state variables, which introduces a nonlinear relationship between the two compartments. This nonlinear relationship can explain some apparently paradoxical phenomena such as a local decrease of precipitation accompanied by a runoff increase. The solutions of the resulting water balance equations correspond to two different spatial moisture regimes showing either an increasing or a decreasing atmospheric moisture content along a trajectory starting at the coast, depending on boundary conditions and parameters. The paper discusses how different model parameters (e.g. time scales of precipitation, evaporation or runoff) influence these regimes and how they can create regime switches. Such an analysis has potential to anticipate the range of possible land use and climate changes or to interpret the results of complex land-atmosphere interaction models. Based on derived analytical expressions for the Horton index, the Budyko curve and a precipitation recycling ratio, the analytical framework opens new perspectives for the classification of hydrological systems.

Estimating a-priori kinematic wave model parameters based on regionalization for flash flood forecasting in the Conterminous United States

2016 ◽  
Vol 541 ◽  
pp. 421-433 ◽  
Author(s):  
Humberto Vergara ◽  
Pierre-Emmanuel Kirstetter ◽  
Jonathan J. Gourley ◽  
Zachary L. Flamig ◽  
Yang Hong ◽  
...  
Keyword(s):  
United States ◽  
Flash Flood ◽  
A Priori ◽  
Wave Model ◽  
Flood Forecasting ◽  
Model Parameters ◽  
Kinematic Wave ◽  
Kinematic Wave Model ◽  
Flash Flood Forecasting

A Nonlinear Shear Deformable Nanoplate Model Including Surface Effects for Large Amplitude Vibrations of Rectangular Nanoplates with Various Boundary Conditions

2015 ◽  
Vol 07 (05) ◽  
pp. 1550076 ◽  
Author(s):  
Reza Ansari ◽  
Mostafa Faghih Shojaei ◽  
Vahid Mohammadi ◽  
Raheb Gholami ◽  
Mohammad Ali Darabi
Keyword(s):  
Boundary Conditions ◽  
Surface Stress ◽  
Equations Of Motion ◽  
Continuation Method ◽  
Free Vibrations ◽  
Model Parameters ◽  
Geometrically Nonlinear ◽  
Residual Surface Stress ◽  
Various Boundary Conditions ◽  
Shear Deformable

In this paper, a geometrically nonlinear first-order shear deformable nanoplate model is developed to investigate the size-dependent geometrically nonlinear free vibrations of rectangular nanoplates considering surface stress effects. For this purpose, according to the Gurtin–Murdoch elasticity theory and Hamilton's principle, the governing equations of motion and associated boundary conditions of nanoplates are derived first. Afterwards, the set of obtained nonlinear equations is discretized using the generalized differential quadrature (GDQ) method and then solved by a numerical Galerkin scheme and pseudo arc-length continuation method. Finally, the effects of important model parameters including surface elastic modulus, residual surface stress, surface density, thickness and boundary conditions on the vibration characteristics of rectangular nanoplates are thoroughly investigated. It is found that with the increase of the thickness, nanoplates can experience different vibrational behavior depending on the type of boundary conditions.

Uncertainty Propagation Through a Simulation of Industrial High Pressure Die Casting

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Jiahong Fu ◽  
John Coleman ◽  
Gregory Poole ◽  
Matthew John M. Krane ◽  
Amy Marconnet
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Boundary Conditions ◽  
Die Casting ◽  
Uncertainty Propagation ◽  
Model Parameters ◽  
High Pressure Die Casting ◽  
Output Uncertainty ◽  
Pressure Die Casting ◽  
The Impact

Abstract While numerical models are often used in industry to evaluate the transport phenomena in solidification processes, the uncertainty in the results propagated from uncertain input parameters is rarely considered. In this work, in order to investigate the effects of input uncertainty on the outputs of high pressure die casting (HPDC) simulations, the Center for Prediction of Reliability, Integrity, and Survivability of Microsystems (PRISM) uncertainty quantification (PUQ) framework was applied. Three uncertainty propagation trials investigate the impact of uncertainty in metal material properties, thermal boundary conditions, and a modeling parameter on outputs of interest, such as fraction liquid at different times in the process cycle and shrinkage porosity volume, in an industrial A380 aluminum alloy HPDC process. This quantification of the output uncertainty establishes the reliability of the simulation results and can inform process design choices, such as the determination of the part ejection time. The results are most sensitive to the uncertainty in the interfacial heat transfer (for both outputs of interest) and the feeding effectivity (FE) (a model parameter controlling porosity formation determination), while the other heat transfer boundary conditions, model parameters, and all the properties play a secondary role in output uncertainty.

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