Multi-model approach to quantify groundwater-level prediction uncertainty using an ensemble of global climate models and multiple abstraction scenarios

Acknowledgements. We acknowledge the World Climate Research Programme's Working Group on Coupled Modelling, which is responsible for CMIP, and we thank the climate modelling groups for producing and making available their model output. The fifth author obtained a PhD scholarship from the Fund for Scientific Research (FWO)-Flanders. This financial support is gratefully acknowledged. Data availability. The climate model data are publicly available through the website of the Earth System Grid Federation (https://esgf.llnl.gov, last access: 8 May 2019). Other data used in this study are summarized and presented in the figures, tables, references, and the Supplement. Additional data, model code and results are available upon request to the first ([email protected]) and last ([email protected]) authors.Peer reviewedPublisher PD

Advanced spatially hybrid fluid-kinetic modelling of plasma-edge neutrals and application to ITER case using SOLPS-ITER

| openaire: EC/H2020/633053/EU//EUROfusion Funding Information: The first author is funded by a PhD fellowship of the Research Foundation—Flanders. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 and 2019–2020 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Centre), funded by the Research Foundation Flanders (FWO), and the Flemish Government—department EWI. 1 Publisher Copyright: © 2022 Wiley-VCH GmbH.A spatially hybrid fluid-kinetic approach for the efficient simulation of plasma-edge neutrals is extended with a kinetic-fluid condensation process and an automated approach to select a fluid or kinetic treatment at each point along the divertor targets. With the proposed hybrid fluid-kinetic methods, the dominant charge–exchange reaction can be largely removed from the kinetic neutral simulation. The hybrid methods achieve quantitative agreement with the standard kinetic approach, with relative errors on the peak target plasma density and peak target ion flux density of 5–30%, while the Central Processing Unit (CPU) time for the kinetic neutral solver is reduced by a factor 3–6.Peer reviewe

Klaar voor klimaatverandering - Opmaak van een risico- en kwetsbaarheidsanalyse in functie van klimaatadaptatie en uitwerken van adaptatiebeleid op maat van en voor de provincie Antwerpen

nrpages: 103status: publishe

Validation of SOLPS-ITER simulations with kinetic, fluid, and hybrid neutral models for JET-ILW low-confinement mode plasmas

| openaire: EC/H2020/101052200/EU//EUROfusion Funding Information: This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No 101052200 – EUROfusion). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them. W. Van Uytven is funded by a PhD fellowship of the Research Foundation - Flanders . The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Research Foundation Flanders (FWO) and the Flemish Government - department EWI . Publisher Copyright: © 2022 The AuthorsFor JET L-mode plasmas in low-recycling conditions (electron temperature at the outer strike point, Te,ot≳30eV), SOLPS-ITER simulations agree within the error bars for the experimental profiles at the low-field side (LFS) divertor target. The peak Balmer-α (Dα) emission in the LFS divertor agrees within the error bars of the KS3 filterscope diagnostic, but is approximately 30% lower than the peak value of the KT1 spectrometer. Simulations have been performed with fluid, kinetic, and hybrid models for the neutrals. The large fluid-kinetic discrepancies of more than a factor 2 are successfully corrected by using a hybrid fluid-kinetic approach, for which kinetic atoms are transferred to the fluid population when the local Knudsen number of the atom becomes smaller than a user-defined transition Knudsen number Knt. The hybrid-kinetic discrepancies are limited to a few % for Knt≤100. When increasing the upstream density to high-recycling conditions, at the onset of detachment (Te,ot≈5eV), the simulations predict more than a factor 2 lower peak ion saturation current to the LFS divertor than the experiments. Also the Dα emission is underpredicted with approximately a factor 2. For these high-recycling conditions, the fluid-kinetic discrepancies are limited to maximum 50%, which are again corrected by using the hybrid approach.Peer reviewe

Urban Networks on the Move : The Austrian Netherlands’ Transit Policy and the Development of the Belgian Urban Networks in the Eighteenth Century (1704–1793)

International audienc

Fluid, kinetic and hybrid approaches for neutral and trace ion edge transport modelling in fusion devices

Neutral gas physics and neutral interactions with the plasma are key aspects of edge plasma and divertor physics in a fusion reactor including the detachment phenomenon often seen as key to dealing with the power exhaust challenges. A full physics description of the neutral gas dynamics requires a 6D kinetic approach, potentially time dependent, where the details of the wall geometry play a substantial role, to the extent that, e.g., the subdivertor region has to be included. The Monte Carlo (MC) approach used for about 30 years in EIRENE [1], is well suited to solve these types of complex problems. Indeed, the MC approach allows simulating the 6D kinetic equation without having to store the velocity distribution on a 6D grid, at the cost of introducing statistical noise. MC also provides very good flexibility in terms of geometry and atomic and molecular (A&M) processes. However, it becomes computationally extremely demanding in high-collisional regions (HCR) as anticipated in ITER and DEMO. Parallelization on particles helps reducing the simulation wall clock time, but to provide speed-up in situations where single trajectories potentially involve a very large number of A&M events, it is important to derive a hierarchy of models in terms of accuracy and to clearly identify for what type of physics issues they provide reliable answers. It was demonstrated that advanced fluid neutral (AFN) models are very accurate in HCRs, and at least an order of magnitude faster than fully kinetic simulations. Based on these fluid models, three hybrid fluid-kinetic approaches are introduced: a spatially hybrid technique (SpH), a micro-Macro hybrid method (mMH), and an asymptotic-preserving MC (APMC) scheme, to combine the efficiency of a fluid model with the accuracy of a kinetic description. In addition, atomic and molecular ions involved in the edge plasma chemistry can also be treated kinetically within the MC solver, opening the way for further hybridisation by enabling kinetic impurity ion transport calculations. This paper aims to give an overview of methods mentioned and suggests the most prospective combinations to be developed

Fluid, kinetic and hybrid approaches for neutral and trace ion edge transport modelling in fusion devices

| openaire: EC/H2020/633053/EU//EUROfusion Funding Information: The paper presents a joint effort within the EUROfusion Theory and Advanced Simulation Coordination (E-TASC), task ‘NGM’ 2019–2020 and the related O-EIRENE HLST project. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 and 2019–2020 under Grant Agreement No. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. W. Van Uytven is funded by a PhD fellowship of the Research Foundation Flanders (FWO). Parts of the work were supported by the Research Foundation Flanders (FWO) under project Grant G078316N. Publisher Copyright: © 2022 The Author(s). Published on behalf of IAEA by IOP Publishing Ltd.Neutral gas physics and neutral interactions with the plasma are key aspects of edge plasma and divertor physics in a fusion reactor including the detachment phenomenon often seen as key to dealing with the power exhaust challenges. A full physics description of the neutral gas dynamics requires a 6D kinetic approach, potentially time dependent, where the details of the wall geometry play a substantial role, to the extent that, e.g., the subdivertor region has to be included. The Monte Carlo (MC) approach used for about 30 years in EIRENE (Reiter et al 2005 Fusion Sci. Technol. 47 172-86), is well suited to solve these types of complex problems. Indeed, the MC approach allows simulating the 6D kinetic equation without having to store the velocity distribution on a 6D grid, at the cost of introducing statistical noise. MC also provides very good flexibility in terms of geometry and atomic and molecular (A&M) processes. However, it becomes computationally extremely demanding in high-collisional regions (HCRs) as anticipated in ITER and DEMO. Parallelization on particles helps reducing the simulation wall clock time, but to provide speed-up in situations where single trajectories potentially involve a very large number of A&M events, it is important to derive a hierarchy of models in terms of accuracy and to clearly identify for what type of physics issues they provide reliable answers. It was demonstrated that advanced fluid neutral models are very accurate in HCRs, and at least an order of magnitude faster than fully kinetic simulations. Based on these fluid models, three hybrid fluid-kinetic approaches are introduced: a spatially hybrid technique, a micro-macro hybrid method, and an asymptotic-preserving MC scheme, to combine the efficiency of a fluid model with the accuracy of a kinetic description. In addition, A&M ions involved in the edge plasma chemistry can also be treated kinetically within the MC solver, opening the way for further hybridisation by enabling kinetic impurity ion transport calculations. This paper aims to give an overview of methods mentioned and suggests the most prospective combinations to be developed.Peer reviewe