scholarly journals Benchmarking 2D against 3D FDTD codes for the assessment of the measurement performance of a low field side plasma position reflectometer applicable to IDTT

2022 ◽  
Vol 17 (01) ◽  
pp. C01017
Author(s):  
F. da Silva ◽  
E. Ricardo ◽  
J. Ferreira ◽  
J. Santos ◽  
S. Heuraux ◽  
...  
Keyword(s):  
High Performance ◽  
Three Dimensional ◽  
Test Facility ◽  
Fusion Plasmas ◽  
Full Wave ◽  
Low Field ◽  
Plasma Position ◽  
Divertor Tokamak ◽  
Difference Time ◽  
Performance Computing

Abstract O-mode reflectometry, a technique to diagnose fusion plasmas, is foreseen as a source of real-time (RT) plasma position and shape measurements for control purposes in the coming generation of machines such as DEMO. It is, thus, of paramount importance to predict the behavior and capabilities of these new reflectometry systems using synthetic diagnostics. Finite-difference time-domain (FDTD) time-dependent codes allow for a comprehensive description of reflectometry but are computationally demanding, especially when it comes to three-dimensional (3D) simulations, which requires access to High Performance Computing (HPC) facilities, making the use of two-dimensional (2D) codes much more common. It is important to understand the compromises made when using a 2D model in order to decide if it is applicable or if a 3D approach is required. This work attempts to answer this question by comparing simulations of a potential plasma position reflectometer (PPR) at the Low Field-Side (LFS) on the Italian Divertor Tokamak Test facility (IDTT) carried out using two full-wave FDTD codes, REFMULF (2D) and REFMUL3 (3D). In particular, the simulations consider one of IDTT’s foreseen plasma scenarios, namely, a Single Null (SN) configuration, at the Start Of Flat-top (SOF) of the plasma current.

The structure of self-sustained instability, transition and turbulence in the separating boundary layer under an internal solitary wave of depression

2021 ◽  
Author(s):  
Peter Diamessis ◽  
Takahiro Sakai ◽  
Gustaaf Jacobs
Keyword(s):  
Boundary Layer ◽  
Large Amplitude ◽  
High Performance ◽  
Separation Bubble ◽  
Computational Cost ◽  
Three Dimensional ◽  
Instability Mode ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Performance Computing

<p>The development of the separated bottom boundary layer (BBL) in the footprint of a large-amplitude ISW of depression is examined using high-accuracy/resolution implicit Large Eddy Simulation. The talk will focus on a single relatively idealized case of a large-amplitude ISW propagating against an oncoming barotropic current with its own, initially laminar, BBL under the inevitable restriction of laboratory-scale Reynolds number. Significant discussion will be dedicated to the non-trivial computational cost of setting up and conducting the above simulation, within long domains and over long-integration times, in a high-performance-computing environment. Results will focus on documenting the full downstream evolution of the structure of the separated BBL development. Particular emphasis will be placed on the existence of a three-dimensional global instability mode, at the core of the separation bubble where typically one might assume two-dimensional dynamics. The particular instability mode is spontaneously excited and is considered responsible for the self-sustained nature of the resulting near-bed turbulent wake in the lee of the ISW. Fundamental mean BBL flow metrics will then be presented along with a short discussion for potential for particulate resuspension. The talk will close with a discussion of the relevance of the existing flow configuration to both the laboratory and ocean, in light of recent measurements in the NW Australian Shelf.<br><br></p>

PE-ALD of Ge1-xSx amorphous chalcogenide alloys for OTS applications

2021 ◽  
Author(s):  
Myoungsub Kim ◽  
Youngjun Kim ◽  
Minkyu Lee ◽  
Seok Man Hong ◽  
Hyung Keun Kim ◽  
...  
Keyword(s):  
High Performance Computing ◽  
High Performance ◽  
Memory Hierarchy ◽  
Three Dimensional ◽  
Cross Point ◽  
Computing Systems ◽  
Amorphous Chalcogenide ◽  
Threshold Switching ◽  
Chalcogenide Alloys ◽  
Performance Computing

Three-dimensional (3D) cross-point (X-point) technology, including amorphous chalcogenide-based ovonic threshold switching (OTS) selectors, is bringing new changes to the memory hierarchy for high-performance computing systems. To prepare for future 3D...

scholarly journals High performance computing for linear acoustic wave simulation

2021 ◽  
Author(s):  
Fouad Butt
Keyword(s):  
Parallel Computing ◽  
Acoustic Wave ◽  
High Performance ◽  
Three Dimensional ◽  
Wave Model ◽  
Acoustic Fields ◽  
Performance Simulation ◽  
Temporal Complexity ◽  
Spatio Temporal ◽  
Performance Computing

Parallel computing techniques are applied to a linear acoustic wave model to reduce execution time. Three parallel computing models are developed to parallelize computations. The fork-and-join, SPMD and SIMT models define the execution of parallel computations. The precision and efficiency of the linear acoustic wave model are improved through substantial speedups in all implementations. Furthermore, axisymmetric properties of certain acoustic fields lead to a reduction in the spatio-temporal complexity of those acoustic fields by removing redundant computations. The same linear acoustic wave model is also modified and extended to describe wave propagation across multiple media instead of only a single medium. The developed implementations are integrated into a particularly useful package for high performance simulation of two- or three-dimensional linear acoustic elds generated by realistic sources in various fluid media.

scholarly journals High performance computing for three-dimensional agent-based molecular models

2016 ◽  
Vol 68 ◽  
pp. 68-77 ◽  
Author(s):  
G. Pérez-Rodríguez ◽  
M. Pérez-Pérez ◽  
F. Fdez-Riverola ◽  
A. Lourenço
Keyword(s):  
High Performance Computing ◽  
High Performance ◽  
Three Dimensional ◽  
Molecular Models ◽  
Agent Based ◽  
Performance Computing

scholarly journals An Optimized Parallel FDTD Topology for Challenging Electromagnetic Simulations on Supercomputers

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Shugang Jiang ◽  
Yu Zhang ◽  
Zhongchao Lin ◽  
Xunwang Zhao
Keyword(s):  
Message Passing ◽  
High Performance ◽  
Message Passing Interface ◽  
Optimal Topology ◽  
Communication Model ◽  
Electromagnetic Simulations ◽  
General Rules ◽  
Computing Platforms ◽  
Difference Time ◽  
Performance Computing

It may not be a challenge to run a Finite-Difference Time-Domain (FDTD) code for electromagnetic simulations on a supercomputer with more than 10 thousands of CPU cores; however, to make FDTD code work with the highest efficiency is a challenge. In this paper, the performance of parallel FDTD is optimized through MPI (message passing interface) virtual topology, based on which a communication model is established. The general rules of optimal topology are presented according to the model. The performance of the method is tested and analyzed on three high performance computing platforms with different architectures in China. Simulations including an airplane with a 700-wavelength wingspan, and a complex microstrip antenna array with nearly 2000 elements are performed very efficiently using a maximum of 10240 CPU cores.

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