scholarly journals Upscaling of regional models into basin-wide models

2018 ◽  
Author(s):  
Luc Vandenbulcke ◽  
Alexander Barth
Keyword(s):  
Large Scale ◽  
Data Transfer ◽  
Scale Model ◽  
Test Case ◽  
Regional Models ◽  
Western Basin ◽  
Upscaling Technique ◽  
Basin Scale ◽  
Online Exchange ◽  
Set Up

Abstract. Traditionnally, in order for lower-resolution, global- or basin-scale models to benefit from some of the improvements available in higher-resolution regional or coastal models, two-way nesting has to be used. This implies that the parent and child models have to be run together and there is an online exchange of information between both models. This approach is often impossible in operational systems, where different model codes are run by different institutions, often in different countries. Therefor, in practice, these systems use one-way nesting with data transfer only from the large-scale model to the regional models. In this article, it is examined whether it is possible to replace the missing model feedback by data assimilation, avoiding the need to run the models simultaneously. Selected variables from the high-resolution forecasts will be used as pseudo-observations, and assimilated in the lower-resolution models. The method will be called upscaling. A realistic test-case is set up with a model covering the Mediterranean Sea, and a nested model covering its North-Western basin. A simulation using only the basin-scale model is compared with a simulation where both models are run using one-way nesting, and using the upscaling technique on the temperature and salinity variables. It is shown that the representation of some processes, such as the Rhône river plume, are strongly improved in the upscaled model compared to the stand-alone model.

scholarly journals Upscaling of a local model into a larger-scale model

Ocean Science ◽  
2019 ◽  
Vol 15 (2) ◽  
pp. 291-305
Author(s):  
Luc Vandenbulcke ◽  
Alexander Barth
Keyword(s):  
Data Transfer ◽  
Scale Model ◽  
Test Case ◽  
Western Basin ◽  
Nested Model ◽  
Upscaling Technique ◽  
Basin Scale ◽  
Online Exchange ◽  
Operational Systems ◽  
Set Up

Abstract. Traditionally, in order for lower-resolution, global- or basin-scale (regional) models to benefit from some of the improvements available in higher-resolution subregional or coastal models, two-way nesting has to be used. This implies that the parent and child models have to be run together and there is an online exchange of information between both models. This approach is often impossible in operational systems where different model codes are run by different institutions, often in different countries. Therefore, in practice, these systems use one-way nesting with data transfer only from the parent model to the child models. In this article, it is examined whether it is possible to replace the missing feedback (coming from the child model) by data assimilation, avoiding the need to run the models simultaneously. Selected variables from the high-resolution simulation will be used as pseudo-observations and assimilated into the low-resolution models. This method will be called “upscaling”. A realistic test case is set up with a model covering the Mediterranean Sea, and a nested model covering its north-western basin. Under the hypothesis that the nested model has better prediction skills than the parent model, the upscaling method is implemented. Two simulations of the parent model are then compared: the case of one-way nesting (or a stand-alone model) and a simulation using the upscaling technique on the temperature and salinity variables. It is shown that the representation of some processes, such as the Rhône River plume, is strongly improved in the upscaled model compared to the stand-alone model.

Small-Scale Models for Testing Masonry Structures

2010 ◽  
Vol 133-134 ◽  
pp. 497-502 ◽  
Author(s):  
Alvaro Quinonez ◽  
Jennifer Zessin ◽  
Aissata Nutzel ◽  
John Ochsendorf
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
Three Dimensional ◽  
Model Testing ◽  
Scale Model ◽  
Small Scale ◽  
Material Strength ◽  
Masonry Structures ◽  
Scale Models ◽  
Set Up

Experiments may be used to verify numerical and analytical results, but large-scale model testing is associated with high costs and lengthy set-up times. In contrast, small-scale model testing is inexpensive, non-invasive, and easy to replicate over several trials. This paper proposes a new method of masonry model generation using three-dimensional printing technology. Small-scale models are created as an assemblage of individual blocks representing the original structure’s geometry and stereotomy. Two model domes are tested to collapse due to outward support displacements, and experimental data from these tests is compared with analytical predictions. Results of these experiments provide a strong understanding of the mechanics of actual masonry structures and can be used to demonstrate the structural capacity of masonry structures with extensive cracking. Challenges for this work, such as imperfections in the model geometry and construction problems, are also addressed. This experimental method can provide a low-cost alternative for the collapse analysis of complex masonry structures, the safety of which depends primarily on stability rather than material strength.

scholarly journals Experimental Data for the Validation of Numerical Methods: DrivAer Model

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 236
Author(s):  
Max Varney ◽  
Martin Passmore ◽  
Felix Wittmeier ◽  
Timo Kuthada
Keyword(s):  
Product Development Process ◽  
Scale Model ◽  
Test Case ◽  
Full Data ◽  
High Quality ◽  
Validation Data ◽  
Data Set ◽  
Piv Measurements ◽  
Test Conditions ◽  
Set Up

As the automotive industry strives to increase the amount of digital engineering in the product development process, cut costs and improve time to market, the need for high quality validation data has become a pressing requirement. While there is a substantial body of experimental work published in the literature, it is rarely accompanied by access to the data and a sufficient description of the test conditions for a high quality validation study. This paper addresses this by reporting on a comprehensive series of measurements for a 25% scale model of the DrivAer automotive test case. The paper reports on the measurement of the forces and moments, pressures and off body PIV measurements for three rear end body configurations, and summarises and compares the results. A detailed description of the test conditions and wind tunnel set up are included along with access to the full data set.

scholarly journals TIME SCALE FOR MODELING BEACH CHANGE

1986 ◽  
Vol 1 (20) ◽  
pp. 88 ◽  
Author(s):  
Masahiro Ito ◽  
Yoshito Tsuchiya
Keyword(s):  
Time Scale ◽  
Large Scale ◽  
Shoreline Change ◽  
Scale Model ◽  
Experimental Conditions ◽  
Equilibrium Beach Profile ◽  
Beach Processes ◽  
Allowable Range ◽  
Set Up ◽  
Relationship Of

A time scale in the similarity of beach change between model and prototype in transitional beach processes from an initial even slope to an equilibrium is developed using a series of small- and large-scale experiments in which the experimental conditions were set up with the scale-model relationship by the authors (1984). The time scale is obtained empirically as a function of experimental scale. Applied the proposed time scale and the scale-model relationship to model experiments, similarity of morphological beach change such as shoreline change and relative breaker point was well reproduced within the allowable range of experimental error. A semi-theoretical time scale is obtained from the continuity equation, the sediment transport rate, and the scale-model relationship of equilibrium beach profile in two-dimensional beach change. The relation between experimental and semi-theoretical time scale is discussed.

A Boundary Element Method Based on the Hierarchical Matrices and Multipole Expansion Theory for Acoustic Problems

2018 ◽  
Vol 15 (03) ◽  
pp. 1850009 ◽  
Author(s):  
Xiujuan Liu ◽  
Haijun Wu ◽  
Weikang Jiang
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Large Scale ◽  
Multipole Expansion ◽  
Hierarchical Matrices ◽  
Low Rank ◽  
Scale Model ◽  
Degenerate Kernel ◽  
Set Up ◽  
Element Method

The coefficient matrices of conventional boundary element method (CBEM) are dense and fully populated. Special techniques such as hierarchical matrices (H-matrices) format are required to extent its ability of handling large-scale problems. Adaptive cross approximation (ACA) algorithm is a widely adopted algorithm to obtain the H-matrices. However, the accuracy of the ACA boundary element method (ACABEM) cannot be adjusted by changing the tolerance [Formula: see text] when it exceeds a certain value. In this paper, the degenerate kernel approximation idea for the low-rank matrices is developed to build a fast BEM for acoustic problems by exploring the multipole expansion of the kernel, which is referred as the multipole expansion H-matrices boundary element method (ME-H-BEM). The newly developed algorithm compresses the far-field submatrices into low rank submatrices with the expansion terms of Green’s function. The obtained H-matrices are applied in conjunction with the generalized minimal residual method (GMRES) to solve acoustic problems. Numerical examples are carefully set up to compare the accuracy, efficiency as well as memory consumption of the CBEM, ACABEM, fast multipole boundary element method (FMBEM) and ME-H-BEM. The results of a pulsating sphere indicate that the ME-H-BEM keeps both storage and operation logarithmic-linear complexity of the H-matrices format as the ACABEM does. Moreover, the ME-H-BEM can achieve better convergence and higher accuracy than the ACABEM. For the analyzed complicated large-scale model, the ME-H-BEM with appropriate number of expansion terms has an advantage in terms of efficiency as compared with the ACABEM. Compared with the FMBEM, the ME-H-BEM is easier to be implemented.

Large-Scale Experiments of Wave-Overtopping Loads on Walls: Layer Thicknesses and Velocities

2018 ◽  
Author(s):  
Lorenzo Cappietti ◽  
Irene Simonetti ◽  
Andrea Esposito ◽  
Maximilian Streicher ◽  
Andreas Kortenhaus ◽  
...  
Keyword(s):  
Large Scale ◽  
Scale Validation ◽  
Irregular Waves ◽  
Scale Model ◽  
Small Scale ◽  
Wave Loads ◽  
Wave Overtopping ◽  
Large Scale Model ◽  
Vertical Walls ◽  
Set Up

Wave-Overtopping loads on vertical walls, such as those located on top of a dike, have been investigated in several small-scale experiments in the past. A large-scale validation for a mild foreshore situation is still missing. Hence the WALOWA (WAve LOads on WAlls) experimental campaign was carried out to address this topic. This paper, first presents a description of the large-scale model, the measurement set-up and the experimental methodologies, then it focuses on the layer thicknesses and velocities of the flows created on the promenade by the wave overtopping. A set of resistive wave gauges, ultrasonic distance sensors and velocimeters have been used to conduct these measurements. Preliminary data analysis and results, related to a 1000 irregular waves long test, are discussed. The momentum flux of these flows is studied and its implications, for the wave-overtopping loads acting on the vertical walls, are highlighted.

scholarly journals EXTERNAL AND INTERNAL WAVE SET-UP AT POROUS PBA REVETMENTS ON A SAND FOUNDATION

2012 ◽  
Vol 1 (33) ◽  
pp. 27
Author(s):  
Gisa Foyer ◽  
Hocine Oumeraci
Keyword(s):  
Large Scale ◽  
Wave Length ◽  
Irregular Waves ◽  
Scale Model ◽  
Large Scale Model ◽  
Internal Set ◽  
Deep Water Wave ◽  
Set Up ◽  
The Stability ◽  
Almost All

Wave set-up is generally considered for the stability analysis of beaches, but not or not explicitly for the design of revetments. Based on large-scale model results with regular and irregular waves, it is shown in this paper that this is not justified. For this purpose, the wave set-up on a porous bonded revetment and the related internal set-up in the sand foundation below the revetment are analysed for different breaker types. The results particularly show that (i) considerable set-up values are obtained for almost all breaker types, (ii) a good correlation exists with the deep water wave length for both external and internal set-up and (iii) the internal set-up is significantly affected by the wave set-up on the slope. Empirical formulae for the prediction of the external and internal set-up are also proposed for both regular and irregular waves.

Large-Scale Model Investigation for Monopile Decommissioning of Offshore Wind Turbines: Overpressure and Vibratory Pile

2021 ◽  
Author(s):  
Nils Hinzmann ◽  
Patrick Lehn ◽  
Jörg Gattermann
Keyword(s):  
Large Scale ◽  
Planning Process ◽  
Complete Removal ◽  
Offshore Wind ◽  
Scale Model ◽  
Offshore Wind Turbines ◽  
Large Scale Model ◽  
First Results ◽  
Set Up ◽  
Large Scale Tests

Abstract As of now, only a small number of offshore foundations, related to offshore wind energy, were decommissioned in Europe. With a diameter up to nine meter, an embedment of about 40 meter and a set up effect over 25 years, the necessary force to pull the pile out of the seabed can be assumed, if at all determinable, to be enormous. The piles that were decommissioned were cut beneath the mud line, which leaves approximately one third of the foundation permanently in the seabed. Different methods and techniques for a complete removal of offshore pile foundation are currently investigated within the project DeCoMP. Vibratory extraction aims for a reduction of the pile skin friction by creating a layer of less density between the pile shaft and pending soil. During the design and planning process for vibratory installation or extraction a drivability prediction is a key element. In order to identify and characterize soil parameter for the numerical simulation of a drivability prediction, large-scale tests are performed by the Institute of Geomechanics and Geotechnics of the Technische Universität Braunschweig (IGG-TUBS) [1]. In this paper first results of pilot tests with two vibrators are presented and key elements such as crane uplift, frequency and acceleration displayed.

Platelet Anti-Aggregating Activity and Tolerance of Clopidogrel in Atherosclerotic Patients

1996 ◽  
Vol 76 (06) ◽  
pp. 0939-0943 ◽  
Author(s):  
B Boneu ◽  
G Destelle ◽  
Keyword(s):  
Platelet Aggregation ◽  
Large Scale ◽  
Bleeding Time ◽  
Antithrombotic Activity ◽  
Ambulatory Patients ◽  
Patients At Risk ◽  
Set Up ◽  
Ischemic Events ◽  
Large Scale Clinical Trial ◽  
Selection Of

SummaryThe anti-aggregating activity of five rising doses of clopidogrel has been compared to that of ticlopidine in atherosclerotic patients. The aim of this study was to determine the dose of clopidogrel which should be tested in a large scale clinical trial of secondary prevention of ischemic events in patients suffering from vascular manifestations of atherosclerosis [CAPRIE (Clopidogrel vs Aspirin in Patients at Risk of Ischemic Events) trial]. A multicenter study involving 9 haematological laboratories and 29 clinical centers was set up. One hundred and fifty ambulatory patients were randomized into one of the seven following groups: clopidogrel at doses of 10, 25, 50,75 or 100 mg OD, ticlopidine 250 mg BID or placebo. ADP and collagen-induced platelet aggregation tests were performed before starting treatment and after 7 and 28 days. Bleeding time was performed on days 0 and 28. Patients were seen on days 0, 7 and 28 to check the clinical and biological tolerability of the treatment. Clopidogrel exerted a dose-related inhibition of ADP-induced platelet aggregation and bleeding time prolongation. In the presence of ADP (5 \lM) this inhibition ranged between 29% and 44% in comparison to pretreatment values. The bleeding times were prolonged by 1.5 to 1.7 times. These effects were non significantly different from those produced by ticlopidine. The clinical tolerability was good or fair in 97.5% of the patients. No haematological adverse events were recorded. These results allowed the selection of 75 mg once a day to evaluate and compare the antithrombotic activity of clopidogrel to that of aspirin in the CAPRIE trial.

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