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.

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 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.

The Emergence of Rabbinic Culture from the Perspective of Qumran

2015 ◽  
Vol 6 (2) ◽  
pp. 253-274
Author(s):  
Vered Noam
Keyword(s):  
Early Stage ◽  
Second Temple ◽  
Test Case ◽  
Literary Works ◽  
Jewish Culture ◽  
The Bible ◽  
Set Up

The rabbinic halakhic system, with its many facets and the literary works that comprise it, reflects a new Jewish culture, almost completely distinct in its halakhic content and scope from the biblical and postbiblical culture that preceded it. By examining Jewish legislation in the area of corpse impurity as a test case, the article studies the implications of Qumranic halakhah, as a way-station between the Bible and the Mishnah, for understanding how Tannaitic halakhah developed. The impression obtained from the material reviewed in the article is that the direction of the “Tannaitic revolution” was charted, its methods set up, and its principles established, at a surprisingly early stage, before the destruction of the Second Temple, and thus at the same time that the Qumran literature was created.

Main topics and recent experiences for environmental monitoring and modelling diffuse pollution

1996 ◽  
Vol 33 (4-5) ◽  
pp. 63-72
Author(s):  
Federico Preti
Keyword(s):  
Groundwater Contamination ◽  
Scientific Literature ◽  
Practical Experience ◽  
Field Monitoring ◽  
Research Field ◽  
Scale Model ◽  
Nonpoint Pollution ◽  
Nonpoint Sources ◽  
Test Models ◽  
Basin Scale

Monitoring and modelling are two complementary instruments necessary for the analysis of pollution phenomena, such as groundwater contamination and lakes eutrophication, often generated by diffuse (nonpoint) sources (NPS). A review of scientific literature has been conducted to obtain the information necessary to develop a correct methodology relative to environmental field monitoring and modelling agricultural nonpoint pollution. A questionnaire has been handed out to several researchers who are involved in this research field in order to learn of other pertinent activities being undertaken and to facilitate the exchange of information. Testing and verification of a methodology for the analysis of contamination caused by the use of agrochemicals, based on field monitoring studies and the application of a distributed nonpoint pollution model, have been conducted in Italy. Based on the research developed and practical experience, some of the main guidelines for conducting studies of pollution processes caused by agriculture as well as a summary of theoretical and practical aspects encountered in the design of field and basin scale model validation studies and in the use of published experimental results to test models can be proposed.

scholarly journals Winter Inputs Buffer Streamflow Sensitivity to Snowpack Losses in the Salt River Watershed in the Lower Colorado River Basin

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 3
Author(s):  
Marcos D. Robles ◽  
John C. Hammond ◽  
Stephanie K. Kampf ◽  
Joel A. Biederman ◽  
Eleonora M. C. Demaria
Keyword(s):  
River Basin ◽  
Colorado River ◽  
Snow Accumulation ◽  
Colorado River Basin ◽  
Scale Model ◽  
Annual Streamflow ◽  
Basin Scale ◽  
Salt River ◽  
Lower Colorado River Basin ◽  
Lower Colorado River

Recent streamflow declines in the Upper Colorado River Basin raise concerns about the sensitivity of water supply for 40 million people to rising temperatures. Yet, other studies in western US river basins present a paradox: streamflow has not consistently declined with warming and snow loss. A potential explanation for this lack of consistency is warming-induced production of winter runoff when potential evaporative losses are low. This mechanism is more likely in basins at lower elevations or latitudes with relatively warm winter temperatures and intermittent snowpacks. We test whether this accounts for streamflow patterns in nine gaged basins of the Salt River and its tributaries, which is a sub-basin in the Lower Colorado River Basin (LCRB). We develop a basin-scale model that separates snow and rainfall inputs and simulates snow accumulation and melt using temperature, precipitation, and relative humidity. Despite significant warming from 1968–2011 and snow loss in many of the basins, annual and seasonal streamflow did not decline. Between 25% and 50% of annual streamflow is generated in winter (NDJF) when runoff ratios are generally higher and potential evapotranspiration losses are one-third of potential losses in spring (MAMJ). Sub-annual streamflow responses to winter inputs were larger and more efficient than spring and summer responses and their frequencies and magnitudes increased in 1968–2011 compared to 1929–1967. In total, 75% of the largest winter events were associated with atmospheric rivers, which can produce large cool-season streamflow peaks. We conclude that temperature-induced snow loss in this LCRB sub-basin was moderated by enhanced winter hydrological inputs and streamflow production.

scholarly journals Genesis of mud volcano fluids in the Gulf of Cadiz using a novel basin-scale model approach

2018 ◽  
Vol 243 ◽  
pp. 186-204 ◽  
Author(s):  
Christopher Schmidt ◽  
Ewa Burwicz ◽  
Christian Hensen ◽  
Klaus Wallmann ◽  
Sara Martínez-Loriente ◽  
...  
Keyword(s):  
Mud Volcano ◽  
Scale Model ◽  
Gulf Of Cadiz ◽  
Basin Scale ◽  
Gulf Of Cádiz ◽  
Model Approach

scholarly journals How to Implement Safe, Efficient and Cost-Effective SARS-CoV-2 Testing in Urban and Rural Schools within One Month

COVID ◽  
2021 ◽  
Vol 1 (4) ◽  
pp. 717-727
Author(s):  
Parastoo Kheiroddin ◽  
Magdalena Gründl ◽  
Michael Althammer ◽  
Patricia Schöberl ◽  
Linda Plail ◽  
...  
Keyword(s):  
Data Transfer ◽  
Cost Effective ◽  
Testing System ◽  
Successful Implementation ◽  
Rural And Urban ◽  
Local Involvement ◽  
Working Day ◽  
Set Up ◽  
The Individual ◽  
Time Required

(1) Background: With vaccination and new variants of SARS-CoV-2 on the horizon, efficient testing in schools may enable prevention of mass infection outbreaks, keeping schools safe places and buying time until decisions on feasibility and the necessity of vaccination in children and youth are made. We established, in the course of the WICOVIR (Where Is the COrona VIRus) study, that gargle-based pool-PCR testing offers a feasible, efficient, and safe testing system for schools in Germany when applied by central university laboratories. (2) Objectives: We evaluated whether this approach can be implemented in different rural and urban settings. (3) Methods: We assessed the arrangements required for successful implementation of the WICOVIR approach in a variety of settings in terms of transport logistics, data transfer and pre-existing laboratory set-up, as well as the time required to establish the set-up. (4) Results: We found that once regulatory issues have been overcome, all challenges pertaining to logistics, data transfer, and laboratory testing on different platforms can be solved within one month. Pooling and depooling of samples down to the individual test result were achievable within one working day in all settings. Local involvement of the community and decentralized set-ups were keys for success. (5) Conclusion: The WICOVIR gargle-based pool-PCR system is so robust and simple that it can be implemented within one month in all settings now or in future pandemics.

scholarly journals A Scale Model of Tension Structures in Road Tunnels to Optimize the Use of Solar Light for Energy Saving

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Antonio Peña-García ◽  
Luisa-María Gil-Martín ◽  
Roberto Escribano ◽  
Antonio Espín-Estrella
Keyword(s):  
Energy Savings ◽  
Construction Materials ◽  
Electricity Consumption ◽  
Scale Model ◽  
Major Influence ◽  
Road Tunnels ◽  
Tension Structures ◽  
Materials Used ◽  
Set Up ◽  
New Equation

Shifting the threshold zone of road tunnels with semitransparent tension structures has shown itself to be an effective way of saving energy in regards to electricity consumption, maintenance, and construction materials used in the electrical lighting, thus lessening negative environmental impacts. Even though the shape of the tension structure has a major influence on energy savings, the optimal type of structure for each tunnel is often difficult to determine, because experiments using real tunnels are extremely expensive. It is thus necessary to find methods of doing this that are both reliable as well as economical. In this research study, three candidate structures were set up at the portal of a scale model of a real tunnel. The energy savings in each case were analyzed and compared. As a result, it was possible to formulate a new equation that calculates the energy savings in the threshold zone.

High Resolution Large Eddy Simulations to Evaluate Turbulence Properties Within a Real Helicopter Engine Combustor

2018 ◽  
Author(s):  
Charlie Koupper ◽  
Jean Lamouroux ◽  
Stephane Richard ◽  
Gabriel Staffelbach
Keyword(s):  
Gas Turbine ◽  
Turbulence Intensity ◽  
Numerical Scheme ◽  
Mesh Refinement ◽  
Large Eddy Simulations ◽  
Scale Model ◽  
Large Eddy ◽  
Set Up ◽  
High Level ◽  
The Impact

In a gas turbine, the combustor is feeding the turbine with hot gases at a high level of turbulence which in turns strongly enhances the heat transfer in the turbine. It is thus of primary importance to properly characterize the turbulence properties found at the exit of a combustor to design the turbine at its real thermal constraint. This being said, real engine measurements of turbulence are extremely rare if not inexistent because of the harsh environment and difficulty to implement experimental techniques that usually operate at isothermal conditions (e.g. hot wire anemometry). As a counterpart, high fidelity unsteady numerical simulations using Large Eddy Simulations (LES) are now mature enough to simulate combustion processes and turbulence within gas turbine combustors. It is thus proposed here to assess the LES methodology to qualify turbulence within a real helicopter engine combustor operating at take-off conditions. In LES, the development of turbulence is primarily driven by the level of real viscosity in the calculation, which is the sum of three contributions: laminar (temperature linked), turbulent (generated by the sub-grid scale model) and artificial (numerics dependent). In this study, the impact of the two main sources of un-desired viscosity is investigated: the mesh refinement and numerical scheme. To do so, three grids containing 11, 33 and 220 million cells for a periodic sector of the combustor are tested as well as centred second (Lax-Wendroff) and third order (TTGC) in space schemes. The turbulence properties (intensity and integral scales) are evaluated based on highly sampled instantaneous solutions and compared between the available simulations. Results show first that the duration of the simulation is important to properly capture the level of turbulence. If short simulations (a few combustor through-times) may be sufficient to evaluate the turbulence intensity, a bias up to 14% is introduced for the turbulence length scales. In terms of calculation set-up, the mesh refinement is found to have a limited influence on the turbulence properties. The numerical scheme influence on the quantities studied here is small, highlighting that the employed schemes dissipation properties are already sufficient for turbulence characterization. Finally, spatially averaged values of turbulence intensity and lengthscale at the combustor exit are almost identically predicted in all cases. However, significant variations from hub to tip are reported, which questions the pertinence to use 0-D turbulence boundary conditions for turbines. Based on the set of simulations discussed in the paper, guidelines can be derived to adequately set-up (mesh, scheme) and run (duration, acquisition frequency) a LES when turbulence evaluation is concerned. As no experimental counterpart to this study is available, the conclusions mainly aim at knowing the possible numerical bias rather than commenting on the predictivity of the approach.

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