Refine your search:     
Report No.
 - 
Search Results: Records 1-11 displayed on this page of 11
  • 1

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Oral presentation

Full-f gyrokinetic simulations at the Exa-scale

Idomura, Yasuhiro

no journal, , 

Full-f gyrokinetic simulations are important tools for estimating confinement properties of fusion plasmas. On Peta-scale machines, capabilities of full-f gyrokinetic simulations have been significantly expanded, and the understanding of ITER-relevant issues such as the plasma size scaling of turbulent transport has been dramatically advanced. On the next generation Exa-scale machines, it is expected that core operation scenario of ITER will be optimized by full-f gyrokinetic simulations of turbulent burning plasmas. In this talk, we discuss physical and computational challenges towards such burning plasma simulations.

Oral presentation

Remote visualization of massive data using particle-based volume rendering

Kawamura, Takuma; Idomura, Yasuhiro; Miyamura, Hiroko; Takemiya, Hiroshi

no journal, , 

Visualization and analysis of extreme scale data are important issues in the next generation Exa-scale simulations. In order to resolve this issue, a remote visualization system has been developed based on the particle-based volume rendering technique. The system connects a supercomputer and a PC via a Client/Server type distributed processing model. Extreme scale data is converted to small particle data via massively parallel data processing on a supercomputer, and the particle data is transferred and rendered on a PC. In this talk, we discuss the performance of remote visualization using the K-computer.

Oral presentation

Modeling of fusion materials degradation

Suzudo, Tomoaki

no journal, , 

In this presentation we discuss what kinds of fusion material research can be considered for the next generation supercomputer after Kei. Since fusion materials are used in extremely severe environment, their degradation largely influences the lifespan and economical efficiency of these reactors. It is widely known that the degradation mechanism, for example, due to neutron irradiation is extremely complicated, we have to resort to large-scale atomistic simulations. Thus we expect that the next generation supercomputer shall support the clarification of the degradation mechanism and its accurate prediction.

Oral presentation

Optimization of fusion plasma codes

Asahi, Yuichi; Latu, G.*; Ina, Takuya; Idomura, Yasuhiro; Virginie, G.*; Garbet, X.*

no journal, , 

We present the optimization of kernels from fusion plasma codes, GYSELA and GT5D, on Tera-flops many-core architecturesincluding accelerators (Xeon Phi, GPU), and a multi-core CPUs (FX100). GYSELA kernel is based on a semi-Lagrangian scheme with high arithmetic intensity. Through the optimization of GYSELA kernel on Xeon Phi, we show the importance of the vectorization on Xeon Phi. For GT5D kernel, which is based on a finite difference scheme, a sophisticated memory access is necessary for high performance. Through the optimization of GT5D kernel on GPUs, we show the effective optimization for memory access on GPUs.

Oral presentation

Progress of full-f gyrokinetic simulations including a new hybrid kinetic electron model

Idomura, Yasuhiro

no journal, , 

A Gyrokinetic Toroidal 5D full-f Eulerian code GT5D is extended including a new hybrid kinetic electron model, which enables us to address ITER relevant issues related to electron turbulence. In this talk, physics backgrounds and computational properties of the new hybrid kinetic electron model are discussed, and applications of the model to ITER relevant issues such as the isotope effect of turbulent plasma transport and the plasma rotation change induced by electron heating are presented. These simulation studies show that electron turbulence plays a critical role in ITER, and thus, the new hybrid kinetic electron model is essential for analyzing the performance of core plasmas in ITER.

Oral presentation

Development of GT5D for stellarator configurations

Matsuoka, Seikichi; Idomura, Yasuhiro; Satake, Shinsuke*

no journal, , 

Global full-f gyrokinetic simulations, in which the gyrokinetic equation is solved based on the first principle without the scale separation with respect to the plasma distribution function, attracted much attention in the plasma transport study. Rich physics has been revealed by the simulations in axisymmetric tokamak plasmas such as JT-60 and ITER. However, no full-f simulations in three-dimensional magnetic field equilibria such as stellarators have been reported so far due to their complicated magnetic field geometries. In this work, we extend a full-f gyrokinetic simulation code, GT5D, to treat three-dimensional magnetic equilibria. A new interface code between GT5D and a 3D equilibrium code, VMEC, are developed, in which the geometry and the magnetic field provided by VMEC code is incorporated into GT5D. It is demonstrated that the neoclassical transport physics of GT5D can successfully reproduce results of another neoclassical transport code and a theory.

Oral presentation

Status of fusion sub-project under Post-K project

Idomura, Yasuhiro

no journal, , 

This talk reviews the present status of the fusion sub-project, which has been promoted under the Post-K priority issue from 2016. In order to simulate burning plasmas in ITER, which have enormous spatio-temporal scales, the extension of existing Peta-scale plasma simulations have been addressed at different levels including computing technologies, mathematical algorithms, numerical schemes, and physics models. In particular, the project focused mainly on the development of strong scaling computational techniques and multi-time-scale physics models in order to overcome a gap of time-scales. In this talk, several examples of such multi-time-scale simulations are presented, and the present status of verification and validation studies of developed codes is discussed.

Oral presentation

Modeling of radiation-induced embrittlement of fusion materials

Suzudo, Tomoaki

no journal, , 

Plasma-facing materials used in future nuclear fusion reactors are exposed to high heat and high dose of radiation, and it is necessary to accurately predict the degradation of the materials. Currently, it is almost impossible to experimentally mimic the fusion reactor environment, and computational methodologies are useful for the study of mechanical property changes under such an environment. We recently obtained some new knowledge on how rhenium and osmium, which are produced from tungsten the prime candidate of the plasma-facing materials, influence the material properties under neutron irradiation. In addition, we also conducted modeling studies on how phase separation of iron-chromium alloys, a model alloy of blanket materials, cause hardening. In the current presentation, these two topics are focused.

Oral presentation

Status of GT5D

Idomura, Yasuhiro

no journal, , 

Under the Post-K project, a Gyrokinetic Toroidal 5D full-f Eulerian code GT5D has been developed towards exascale burning plasma simulations on the Post-K machine. In this talk, we review the present status on new computational techniques on GT5D, in which Krylov based sparse matrix solvers for a semi-implicit time integration method occupy the most of computational cost. Recently, we introduced communication-avoiding (CA) Krylov methods, and improved the scalability of GT5D on the latest many-core platforms. We also ported the CA-Krylov solver on the latest GPU platforms, and achieved speedup by more than an order of magnitude.

Oral presentation

Development of GT5D for stellarator configurations

Matsuoka, Seikichi*; Idomura, Yasuhiro; Satake, Shinsuke*; Honda, Mitsuru*; Suzuki, Yasuhiro*

no journal, , 

A Gyrokinetic Toroidal 5D full-f Eulerian code GT5D is extended for three dimensional magnetic configurations such as stellarators and tokamaks with perturbed magnetic fields. An interface program for three dimensional equilibrium magnetic configuration code VMEC is constructed to generate a vector potential used in GT5D. The developed code is verified through benchmark calculations of neoclassical transport and geodesic acoustic modes in a Large Helical Device configuration. The results show quantitative agreements against the three dimensional delta-f particle code FORTEC3D.

Oral presentation

Development of exascale matrix solvers based on communication avoiding algorithms

Imamura, Toshiyuki*; Idomura, Yasuhiro; Ina, Takuya*; Yamashita, Susumu; Onodera, Naoyuki; Ali, Y.*; Yamada, Susumu

no journal, , 

Towards exascale computing on the Post-K computer, a novel matrix solvers are developed by using communication avoiding algorithms. In this talk, we review two main approaches used in the three-dimensional thermal hydraulic multi-phase CFD code, JUPITER. One is a communication avoiding Krylov sub-space method, in which multiple basis vectors are generated and orthogonalized at once to reduce global collective communications. The other is a Krylov sub-space method with multi-grid preconditioning, which dramatically improve convergence property and reduce the number of iterations, and thus, global collective communications. We compare these approaches on the latest many core platform.

11 (Records 1-11 displayed on this page)
  • 1