INTRODUCING GRADUATE STUDENTS INTO PRE-PROCESSING TECHNIQUES FOR ADVANCED NUMERICAL MODELS: APPLICATION TO HYDRODYNAMIC MODELS

2016 ◽  
Author(s):  
Carmen Zarzuelo Romero ◽  
Alejandro López-Ruiz ◽  
Manuel Díez-Minguito ◽  
Antonio Moñino ◽  
Pedro Magaña ◽  
...  
Keyword(s):  
Graduate Students ◽  
Numerical Models ◽  
Hydrodynamic Models ◽  
Processing Techniques

scholarly journals Image-Based Radiodensity Profilometry Measures Early Remodeling at the Bone-Callus Interface in Sheep

2021 ◽  
Author(s):  
Tianyi Ren
Keyword(s):  
Bone Healing ◽  
Callus Formation ◽  
Early Stage ◽  
Numerical Models ◽  
Fracture Repair ◽  
Density Gradients ◽  
Intact Bone ◽  
Processing Techniques ◽  
Early Healing

Bone healing has been traditionally described as a four-phase process: inflammatory response, soft callus formation, hard callus development, and remodeling. The remodeling phase has been largely neglected in most numerical mechanoregulation models of fracture repair in favor of capturing early healing using a pre-defined callus domain. However, in vivo evidence suggests that remodeling occurs concurrently with repair and causes changes in cortical bone adjacent to callus that are typically neglected in numerical models of bone healing. The objective of this study was to use image processing techniques to quantify this early-stage remodeling in ovine osteotomies. To accomplish this, we developed a numerical method for radiodensity profilometry with optimization-based curve fitting to mathematically model the bone density gradients in the radial direction across the cortical wall and callus. After assessing data from 26 sheep, we defined a dimensionless density fitting function that revealed significant remodeling occurring in the cortical wall adjacent to callus during early healing, a 23% average reduction in density compared to intact. This fitting function is robust for modeling radial density gradients in both intact bone and fracture repair scenarios and can capture a wide variety of the healing responses. The fitting function can also be scaled easily for comparison to numerical model predictions and may be useful for validating future mechanoregulatory models of coupled fracture repair and remodeling.

scholarly journals Assessing enigmatic boulder deposits in NE Aegean Sea: importance of historical sources as tool to support hydrodynamic equations

2012 ◽  
Vol 12 (4) ◽  
pp. 1109-1118 ◽  
Author(s):  
M. Vacchi ◽  
A. Rovere ◽  
N. Zouros ◽  
M. Firpo
Keyword(s):  
Numerical Models ◽  
Aegean Sea ◽  
Coastal Hazards ◽  
Hydrodynamic Equations ◽  
Hydrodynamic Models ◽  
Historical Sources ◽  
Field Evidence ◽  
Historical Tsunami ◽  
Storm Wave ◽  
Boulder Deposits

Abstract. Due to their importance in the assessment of coastal hazards, several studies have focused on geomorphological and sedimentological field evidence of catastrophic wave impacts related to historical tsunami events. Among them, many authors used boulder fields as important indicators of past tsunamis, especially in the Mediterranean Sea. The aim of this study was to understand the mechanism of deposition of clusters of large boulders, consisting of beachrock slabs, which were found on the southern coasts of Lesvos Island (NE Aegean Sea). Methods to infer the origin of boulder deposits (tsunami vs. storm wave) are often based on hydrodynamic models even if different environmental complexities are difficult to be incorporated into numerical models. In this study, hydrodynamic equations did not provide unequivocal indication of the mechanism responsible for boulder deposition in the study area. Further analyses, ranging from geomorphologic to seismotectonic data, indicated a tsunami as the most likely cause of displacement of the boulders but still do not allow to totally exclude the extreme storm origin. Additional historical investigations (based on tsunami catalogues, historical photos and aged inhabitants interviews) indicated that the boulders are likely to have been deposited by the tsunami triggered by the 6.7 Ms Chios-Karaburum earthquake of 1949 or, alternatively, by minor effects of the destructive tsunami produced by 1956's Amorgos Island earthquake. Results of this study point out that, at Mediterranean scale, to flank numerical models with the huge amount of the available historical data become a crucial tool in terms of prevention policies related to catastrophic coastal events.

Pollutant dispersion in the nearshore region: modelling and measurements

1995 ◽  
Vol 32 (9-10) ◽  
pp. 169-178 ◽  
Author(s):  
A. Rodriguez ◽  
A. Sánchez-Arcilla ◽  
J. M. Redondo ◽  
E. Bahia ◽  
J. P. Sierra
Keyword(s):  
Field Model ◽  
Surf Zone ◽  
Initial Conditions ◽  
Numerical Models ◽  
Dispersion Model ◽  
Near Field ◽  
Pollutant Dispersion ◽  
Hydrodynamic Models ◽  
Wave Induced ◽  
Sea Outfalls

Some results on pollutant dispersion modelling and tracer measurements for the Mediterranean Spanish coast are presented. Two hydrodynamic models have been used to simulate wind and wave induced circulation in the nearshore and surf zones respectively. A “near field” model has been used in order to simulate the initial conditions for the local “far field” dispersion model. Two study cases are presented: The first one shows the mixing of conservative tracers in a Mediterranean surf zone from an experimental and numerical models used to predict bacterial dispersion from the main sea outfalls of Barcelona City. The comparison between dye dispersion experiments and model in the surf zone is good, while the outfall predictions show the importance of accurately modelling the effects of buoyancy on the plume.

scholarly journals Study of avalanche dynamics by seismic methods, image-processing techniques and numerical models

1998 ◽  
Vol 26 ◽  
pp. 319-323 ◽  
Author(s):  
F. Sabot ◽  
M. Naaim ◽  
F. Granada ◽  
E. Suriñach ◽  
P. Planet ◽  
...  
Keyword(s):  
Image Processing ◽  
Seismic Data ◽  
Numerical Models ◽  
Maximum Velocity ◽  
Seismic Signals ◽  
Image Processing Techniques ◽  
Video Images ◽  
Avalanche Flow ◽  
Processing Techniques

Seismic signals of avalanches, related video images and numerical models were compared to improve the characterization of avalanche phenomena. Seismic data and video images from two artificially released avalanches were analysed to obtain more information about the origin of the signals. Image processing was used to compare the evolution of one avalanche front and the corresponding seismic signals. A numerical model was also used to simulate an avalanche flow in order to obtain mean- and maximum-velocity profiles. Prior to this, the simulated avalanche was verified using video images. The results indicate that the seismic signals recorded correspond to changes in avalanche type and path slope, interaction with obstacles and to phenomena associated with the stopping stage of the avalanche, suggesting that only part of the avalanche was recorded. These results account for the seismic signals previously obtained automatically in a wide avalanche area.

scholarly journals Object-Based Algorithm for the Identification and Tracking of Convective Outflow Boundaries in Numerical Models

2018 ◽  
Vol 146 (12) ◽  
pp. 4179-4200 ◽  
Author(s):  
Hristo G. Chipilski ◽  
Xuguang Wang ◽  
David B. Parsons
Keyword(s):  
Numerical Models ◽  
Ensemble Prediction ◽  
Future Research ◽  
Density Currents ◽  
Retrospective Case ◽  
Ensemble Prediction System ◽  
Convective Systems ◽  
Object Based ◽  
Processing Techniques ◽  
Retrospective Case Study

Abstract A novel object-based algorithm capable of identifying and tracking convective outflow boundaries in convection-allowing numerical models is presented in this study. The most distinct feature of the proposed algorithm is its ability to seamlessly analyze numerically simulated density currents and bores, both of which play an important role in the dynamics of nocturnal convective systems. The unified identification and classification of these morphologically different phenomena is achieved through a multivariate approach combined with appropriate image processing techniques. The tracking component of the algorithm utilizes two dynamical constraints, which improve the object association results in comparison to methods based on statistical assumptions alone. Special attention is placed on some of the outstanding challenges regarding the formulation of the algorithm and possible ways to address those in future research. Apart from describing the technical details behind the algorithm, this study also introduces specific algorithm applications relevant to the analysis and prediction of bores. These applications are illustrated for a retrospective case study simulated with a convection-allowing ensemble prediction system. The paper highlights how the newly developed algorithm tools naturally form a foundation for understanding the initiation, structure, and evolution of bores and convective systems in the nocturnal environment.

scholarly journals Effects of dimensionality on the performance of hydrodynamic models

2021 ◽  
Author(s):  
Mayra Ishikawa ◽  
Wendy Gonzalez ◽  
Orides Golyjeswski ◽  
Gabriela Sales ◽  
J. Andreza Rigotti ◽  
...  
Keyword(s):  
Water Quality ◽  
Water Temperature ◽  
Flow Velocity ◽  
Numerical Models ◽  
Mixed Layer Depth ◽  
Water Reservoir ◽  
Density Currents ◽  
Hydrodynamic Models ◽  
Subtropical Zone ◽  
Drinking Water Reservoir

Abstract. Numerical models are an important tool for simulating temperature, hydrodynamics and water quality in lakes and reservoirs. Existing models differ in dimensionality by considering spatial variations of simulated parameters (e.g., flow velocity and water temperature) in one (1D), two (2D) or three (3D) spatial dimensions. The different approaches are based on different levels of simplification in the description of hydrodynamic processes and result in different demands in computational power. The aim of this study is to compare three models with different dimensionality and to analyze differences between model results in relation to model simplifications. We analyze simulations of thermal stratification, flow velocity, and substance transport by density currents in a medium-sized drinking water reservoir in the subtropical zone, using three widely used open-source models: GLM (1D), CE-QUAL-W2 (2D) and Delft3D (3D). The models were operated with identical initial and boundary conditions over a one-year period. Their performance was assessed by comparing model results with measurements of temperature, flow velocity and turbulence. Results show that all models were capable of simulating the seasonal changes in water temperature and stratification. Flow velocities, only available for the 2D and 3D approaches, were more challenging to reproduce, but 3D simulations showed closer agreement with observations. With increasing dimensionality, the quality of the simulations also increased in terms of error, correlation and variance. None of the models provided good agreement with observations in terms of mixed layer depth, which also affects the spreading of inflowing water as density currents, and the results of water quality models that build on outputs of the hydrodynamic models.

scholarly journals Study of avalanche dynamics by seismic methods, image-processing techniques and numerical models

1998 ◽  
Vol 26 ◽  
pp. 319-323 ◽  
Author(s):  
F. Sabot ◽  
M. Naaim ◽  
F. Granada ◽  
E. Suriñach ◽  
P. Planet ◽  
...  
Keyword(s):  
Image Processing ◽  
Seismic Data ◽  
Numerical Models ◽  
Maximum Velocity ◽  
Seismic Signals ◽  
Image Processing Techniques ◽  
Video Images ◽  
Avalanche Flow ◽  
Processing Techniques

Seismic signals of avalanches, related video images and numerical models were compared to improve the characterization of avalanche phenomena. Seismic data and video images from two artificially released avalanches were analysed to obtain more information about the origin of the signals. Image processing was used to compare the evolution of one avalanche front and the corresponding seismic signals. A numerical model was also used to simulate an avalanche flow in order to obtain mean- and maximum-velocity profiles. Prior to this, the simulated avalanche was verified using video images. The results indicate that the seismic signals recorded correspond to changes in avalanche type and path slope, interaction with obstacles and to phenomena associated with the stopping stage of the avalanche, suggesting that only part of the avalanche was recorded. These results account for the seismic signals previously obtained automatically in a wide avalanche area.

scholarly journals Bridging the gap between supernovae and their remnants through multi-dimensional hydrodynamic modeling

2017 ◽  
Vol 12 (S331) ◽  
pp. 258-267
Author(s):  
S. Orlando ◽  
M. Miceli ◽  
O. Petruk
Keyword(s):  
Physical Properties ◽  
Uniform Distribution ◽  
Supernova Remnants ◽  
Numerical Models ◽  
Hydrodynamic Models ◽  
Cassiopeia A ◽  
Sn 1987A ◽  
Complex Morphology ◽  
Extended Sources ◽  
Early Interaction

AbstractSupernova remnants (SNRs) are diffuse extended sources characterized by a complex morphology and a non-uniform distribution of ejecta. Such a morphology reflects pristine structures and features of the progenitor supernova (SN) and the early interaction of the SN blast wave with the inhomogeneous circumstellar medium (CSM). Deciphering the observations of SNRs might open the possibility to investigate the physical properties of both the interacting ejecta and the shocked CSM. This requires accurate numerical models which describe the evolution from the SN explosion to the remnant development and which connect the emission properties of the remnants to the progenitor SNe. Here we show how multi-dimensional SN-SNR hydrodynamic models have been very effective in deciphering observations of SNR Cassiopeia A and SN 1987A, thus unveiling the structure of ejecta in the immediate aftermath of the SN explosion and constraining the 3D pre-supernova structure and geometry of the environment surrounding the progenitor SN.

scholarly journals Improved Current Estimates from Spar Buoy-Mounted ADCP Measurement Station: A Case Study in the Ligurian Sea

2021 ◽  
Vol 9 (5) ◽  
pp. 466
Author(s):  
Andrea Bordone ◽  
Tiziana Ciuffardi ◽  
Giancarlo Raiteri ◽  
Antonio Schirone ◽  
Roberto Bozzano ◽  
...  
Keyword(s):  
Reference Model ◽  
Numerical Models ◽  
Metal Structure ◽  
Hydrodynamic Models ◽  
Ligurian Sea ◽  
Open Sea ◽  
Marine Current ◽  
Acoustic Doppler Current Profilers ◽  
Good Agreement

Current measurements in the open sea are generally acquired by Acoustic Doppler Current Profilers (ADCPs). In the case of ADCPs mounted on spar buoy, current profiles require to be post-processed, to properly take into account the buoy influence: in fact, ADCP compass may reflect alterations induced by the metal structure of the buoy and apparent currents can occur due to the large displacement of the platform. Uncertainty analysis is finally required to properly consider both these effects and to compute robust velocity estimates. A new methodology is tested for a measurement station in the Ligurian Sea, where an ADCP was mounted on the surface buoy of the W1-M3A (Western 1 Mediterranean Moored Multisensor Array) oceanographic observatory, facing upwards at the depth of about 40 m. Marine current numerical models and historical data in the area have been used as a basis for comparison to test the consistency of the proposed method. A very good agreement is obtained. Only minor discrepancies are reported (e.g., monthly averages from the reference model slightly underestimate the west-east current component along the entire profile), but, in general, the application of the proposed methodology ensures that the spar buoy-mounted ADCP system is able to provide reliable measurements for oceanographic studies and validation of 3D hydrodynamic models.

scholarly journals A Reasoned Comparison between Two Hydrodynamic Models: Delft3D-Flow and ROMS (Regional Oceanic Modelling System)

2019 ◽  
Vol 7 (12) ◽  
pp. 464 ◽  
Author(s):  
Stefano Putzu ◽  
Francesco Enrile ◽  
Giovanni Besio ◽  
Andrea Cucco ◽  
Laura Cutroneo ◽  
...  
Keyword(s):  
Eddy Viscosity ◽  
Numerical Models ◽  
Rectangular Channel ◽  
Free Surface Flows ◽  
Water Levels ◽  
Closure Model ◽  
Hydrodynamic Models ◽  
Tangential Stresses ◽  
The 1960S ◽  
Vertical Eddy

Useful information, such as water levels, currents, salinity and temperature dynamics in water bodies, are obtained through numerical models in order to pursue scientific research or consultancy. Model validation dates back long ago, since such models started to be developed in the 1960s. Despite their usefulness and reliability in complex situations, some issues related to well-known benchmarks are still present. This work aims to analyse in detail the behaviour of the velocity profile, vertical eddy viscosity and tangential stresses at the bed in two cases of free surface flows; namely: uniform flow in an inclined rectangular channel and a wind-induced circulation in a closed basin. Computational results strongly depend on the turbulence closure model employed and a reasoned comparison is necessary to highlight possible improvements of these models. The strong differences that arise are deeply analysed in this work.

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