The NEMO (Nucleus for European Modelling of the Ocean) numerical ocean platform

2020 ◽  
Author(s):  
Guillaume Samson ◽  
Claire Levy ◽  
Nemo System Team
Keyword(s):  
Adaptive Mesh Refinement ◽  
State Of The Art ◽  
Adaptive Mesh ◽  
Ocean Model ◽  
Ocean Dynamics ◽  
Ice Shelves ◽  
Model Code ◽  
Set Up ◽  
Climate Studies

<p>The Nucleus for European Modelling of the Ocean (NEMO) is a state-of-the art modelling platform for oceanographic research, operational oceanography, sesonnal forecasts and climate studies. NEMO includes three major components; the blue ocean (dynamics), the white ocean (sea-ice), the green ocean (ocean biogeochemistry). It also allows coupling through interfaces with atmosphere (through OASIS software), waves, ice-shelves, so as nesting through the adaptive mesh refinement software AGRIF. Some reference configurations and test cases allowing to explore, to set-up and to validate the applications, and a set of tools to use the platform are also available to the community. The whole platform and its documentation are available under free licence.</p><p>The evolution and reliability of NEMO are organised and controlled by a European Consortium between CMCC (Italy), CNRS (France), MOI France), NOC (UK), UKMO (UK).</p><p>Consortium members agree on long term strategy and yearly plans, sharing expertise and efforts within the NEMO System Team: the core team of NEMO developers in order to ensure the successful and sustainable development of the NEMO System as a well-organised, state-of-the-art ocean model code system suitable for both research and operational work</p>

scholarly journals Adaptive Wavelet Methods for Earth Systems Modelling

2021 ◽  
Author(s):  
Nicholas Kevlahan
Keyword(s):  
Adaptive Mesh Refinement ◽  
Climate Models ◽  
Adaptive Mesh ◽  
Mass Conservation ◽  
Ocean Model ◽  
Ocean Dynamics ◽  
Climate Modelling ◽  
Exact Mass ◽  
Adaptive Wavelet ◽  
Wavelet Methods

This paper reviews how dynamically adaptive wavelet methods can be designed to simulate atmosphere and ocean dynamics in both flat and spherical geometries. We highlight the special features that these models must have in order to be valid for climate modelling applications. These include exact mass conservation and various mimetic properties that ensure the solutions remain physically realistic, even in the under-resolved conditions typical of climate models. Particular attention is paid to the implementation of complex topography in adaptive models. Using \textsc{wavetrisk} as an example, we explain in detail how to build a semi-realistic global atmosphere or ocean model of interest to the geophysical community. We end with a discussion of the challenges that remain to developing a realistic dynamically adaptive atmosphere or ocean climate models. These include scale-aware subgrid scale parameterizations of physical processes, such as clouds. Although we focus on adaptive wavelet methods, many of the topics we discuss are relevant for adaptive mesh refinement (AMR).

scholarly journals Adaptive Wavelet Methods for Earth Systems Modelling

Fluids ◽  
2021 ◽  
Vol 6 (7) ◽  
pp. 236
Author(s):  
Nicholas K.-R. Kevlahan
Keyword(s):  
Adaptive Mesh Refinement ◽  
Climate Models ◽  
Adaptive Mesh ◽  
Mass Conservation ◽  
Ocean Model ◽  
Ocean Dynamics ◽  
Climate Modelling ◽  
Exact Mass ◽  
Adaptive Wavelet ◽  
Wavelet Methods

This paper reviews how dynamically adaptive wavelet methods can be designed to simulate atmosphere and ocean dynamics in both flat and spherical geometries. We highlight the special features that these models must have in order to be valid for climate modelling applications. These include exact mass conservation and various mimetic properties that ensure the solutions remain physically realistic, even in the under-resolved conditions typical of climate models. Particular attention is paid to the implementation of complex topography in adaptive models. Using wavetrisk as an example, we explain in detail how to build a semi-realistic global atmosphere or ocean model of interest to the geophysical community. We end with a discussion of the challenges that remain to developing a realistic dynamically adaptive atmosphere or ocean climate models. These include scale-aware subgrid scale parameterizations of physical processes, such as clouds. Although we focus on adaptive wavelet methods, many of the topics we discuss are relevant for adaptive mesh refinement (AMR).

scholarly journals Insights into the physics when modelling cold gas clouds in a hot plasma

2019 ◽  
Vol 490 (1) ◽  
pp. L52-L56
Author(s):  
Bastian Sander ◽  
Gerhard Hensler
Keyword(s):  
Adaptive Mesh Refinement ◽  
Adaptive Mesh ◽  
Careful Consideration ◽  
Necessary Condition ◽  
Interstellar Clouds ◽  
Hot Plasma ◽  
Magnetic Dipole Field ◽  
Set Up ◽  
Self Gravity ◽  
Cold Gas

ABSTRACT This paper aims at studying the reliability of a few frequently raised, but not proven, arguments for the modelling of cold gas clouds embedded in or moving through a hot plasma and at sensitizing modellers to a more careful consideration of unavoidable acting physical processes and their relevance. At first, by numerical simulations we demonstrate the growing effect of self-gravity on interstellar clouds and, by this, moreover argue against their initial set-up as homogeneous. We apply the adaptive-mesh refinement code flash with extensions to metal-dependent radiative cooling and external heating of the gas, self-gravity, mass diffusion, and semi-analytic dissociation of molecules, and ionization of atoms. We show that the criterion of Jeans mass or Bonnor–Ebert mass, respectively, provides only a sufficient but not a necessary condition for self-gravity to be effective, because even low-mass clouds are affected on reasonable dynamical time-scales. The second part of this paper is dedicated to analytically study the reduction of heat conduction by a magnetic dipole field. We demonstrate that in this configuration, the effective heat flow, i.e. integrated over the cloud surface, is suppressed by only 32 per cent by magnetic fields in energy equipartition and still insignificantly for even higher field strengths.

scholarly journals Hydrodynamical Adaptive Mesh Refinement Simulations of Disk Galaxies

2008 ◽  
Vol 4 (S254) ◽  
pp. 445-452
Author(s):  
Brad K. Gibson ◽  
Stéphanie Courty ◽  
Patricia Sánchez-Blázquez ◽  
Romain Teyssier ◽  
Elisa L. House ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Adaptive Mesh Refinement ◽  
Mesh Refinement ◽  
Adaptive Mesh ◽  
Disk Galaxies ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Temporal And Spatial ◽  
Compare And Contrast

AbstractTo date, fully cosmological hydrodynamic disk simulations to redshift zero have only been undertaken with particle-based codes, such as GADGET, Gasoline, or GCD+. In light of the (supposed) limitations of traditional implementations of smoothed particle hydrodynamics (SPH), or at the very least, their respective idiosyncrasies, it is important to explore complementary approaches to the SPH paradigm to galaxy formation. We present the first high-resolution cosmological disk simulations to redshift zero using an adaptive mesh refinement (AMR)-based hydrodynamical code, in this case, RAMSES. We analyse the temporal and spatial evolution of the simulated stellar disks' vertical heating, velocity ellipsoids, stellar populations, vertical and radial abundance gradients (gas and stars), assembly/infall histories, warps/lopsideness, disk edges/truncations (gas and stars), ISM physics implementations, and compare and contrast these properties with our sample of cosmological SPH disks, generated with GCD+. These preliminary results are the first in our long-term Galactic Archaeology Simulation program.

Grid-Convergent Spray Models for Internal Combustion Engine CFD Simulations

2012 ◽  
Author(s):  
P. K. Senecal ◽  
E. Pomraning ◽  
K. J. Richards ◽  
S. Som
Keyword(s):  
Liquid Phase ◽  
Adaptive Mesh Refinement ◽  
State Of The Art ◽  
Combustion Engine ◽  
Adaptive Mesh ◽  
Cfd Simulations ◽  
Modeling Methodology ◽  
Grid Convergence ◽  
Key Features ◽  
Momentum Coupling

A state-of-the-art spray modeling methodology is presented. Key features of the methodology, such as Adaptive Mesh Refinement (AMR), advanced liquid-gas momentum coupling, and improved distribution of the liquid phase, are described. The ability of this approach to use cell sizes much smaller than the nozzle diameter is demonstrated. Grid convergence of key parameters is verified for non-evaporating, evaporating, and reacting spray cases using cell sizes down to 1/32 mm. Grid settings are recommended that optimize the accuracy/runtime tradeoff for RANS-based spray simulations.

Grid-Convergent Spray Models for Internal Combustion Engine Computational Fluid Dynamics Simulations

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
P. K. Senecal ◽  
E. Pomraning ◽  
K. J. Richards ◽  
S. Som
Keyword(s):  
Adaptive Mesh Refinement ◽  
State Of The Art ◽  
Combustion Engine ◽  
Adaptive Mesh ◽  
Modeling Methodology ◽  
Grid Convergence ◽  
Computational Fluid Dynamics Simulations ◽  
Key Features ◽  
Dynamics Simulations ◽  
Momentum Coupling

A state-of-the-art spray modeling methodology is presented. Key features of the methodology, such as adaptive mesh refinement (AMR), advanced liquid–gas momentum coupling, and improved distribution of the liquid phase, are described. The ability of this approach to use cell sizes much smaller than the nozzle diameter is demonstrated. Grid convergence of key parameters is verified for nonevaporating, evaporating, and reacting spray cases using cell sizes down to 1/32 mm. Grid settings are recommended that optimize the accuracy/runtime tradeoff for RANS-based spray simulations.

scholarly journals How to Simulate the Universe in a Computer

2005 ◽  
Vol 22 (3) ◽  
pp. 184-189 ◽  
Author(s):  
Alexander Knebe
Keyword(s):  
Adaptive Mesh Refinement ◽  
Initial Conditions ◽  
Adaptive Mesh ◽  
General Idea ◽  
Short Introduction ◽  
Set Up ◽  
Self Gravity ◽  
Tree Codes ◽  
The Universe ◽  
Broad Overview

AbstractIn this contribution a broad overview of the methodologies of cosmological N-body simulations and a short introduction explaining the general idea behind such simulations is presented. After explaining how to set up the initial conditions using a set of N particles two (diverse) techniques are presented for evolving these particles forward in time under the influence of their self-gravity. One technique (tree codes) is solely based upon a sophistication of the direct particle–particle summation whereas the other method relies on the continuous (de-)construction of arbitrarily shaped grids and is realized in adaptive mesh refinement codes.

Operational Aspects of National Securities Depository Limited (NSDL) in Depository System

2018 ◽  
Vol 6 (8) ◽  
pp. 249
Author(s):  
Rajnikant Kumar
Keyword(s):  
Capital Markets ◽  
Service Providers ◽  
State Of The Art ◽  
Stock Exchanges ◽  
Saving Account ◽  
Business Partners ◽  
Paper Work ◽  
Set Up ◽  
Buy Back ◽  
Operational Aspects

NSDL was registered by the SEBI on June 7, 1996 as India’s first depository to facilitate trading and settlement of securities in the dematerialized form. NSDL has been set up to cater to the demanding needs of the Indian capital markets. NSDL commenced operations on November 08, 1996. NSDL has been promoted by a number of companies, the prominent of them being IDBI, UTI, NSE, SBI, HDFC Bank Ltd., etc. The initial paid up capital of NSDL was Rs. 105 crore which was reduced to Rs. 80 crore. During 2000-2001 through buy-back programme by buying back 2.5 crore shares @ 12 Rs./share. It was done to bring the size of its capital in better alignment with its financial operations and to provide same return to shareholders by gainfully deploying the excess cash available with NSDL. NSDL carries out its activities through service providers such as depository participants (DPs), issuing companies and their registrars and share transfer agents and clearing corporations/ clearing houses of stock exchanges. These entities are NSDL's business partners and are integrated in to the NSDL depository system to provide various services to investors and clearing members. The investor can get depository services through NSDL's depository participants. An investor needs to open a depository account with a depository participant to avail of depository facilities. Depository system essentially aims at eliminating the voluminous and cumbersome paper work involved in the scrip-based system and offers scope for ‘paperless’ trading through state-of-the-art technology. A depository can be compared to a bank. A depository holds securities of investors in the form of electronic accounts, in the same way as bank holds money in a saving account. Besides, holding securities, a depository also provides services related to transactions in securities.

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