VR extension of client server type particle-based volume visualization application

Kawamura, Takuma; Sakamoto, Naohisa*; Osaki, Tsukasa*

Journal of Advanced Simulation in Science and Engineering (Internet), 10(1), p.31 - 39, 2023/02

https://doi.org/10.15748/jasse.10.31

Visualization of large fluid computation results at remote locations by VR, especially using volume rendering, is one of the key challenges in the visualization field. The remote visualization application CS-PBVR is capable of interactive volume rendering of large-scale data in remote locations. In this study, the image generation of CS-PBVR was extended for head-mounted displays to develop a remote VR visualization application, VR-PBVR. We also developed a function that allows manipulation of visualization data by gesture control with both hands in VR space. We applied VR-PBVR to remote volume data and confirmed that it can visualize the data at interactive frame rates.

Numerical analyses of design extension conditions for sodium-cooled fast reactor designed in Japan

Yamano, Hidemasa; Kubo, Shigenobu; Tokizaki, Minako*; Nakamura, Hironori*

Proceedings of International Conference on Topical Issues in Nuclear Installation Safety; Strengthening Safety of Evolutionary and Innovative Reactor Designs (TIC 2022) (Internet), 12 Pages, 2022/10

Specific design features of advanced sodium-cooled fast reactors (SFRs) designed in Japan are a passive reactor shutdown system, a passive decay heat removal system (DHRS), and an in-vessel retention (IVR) concept against an anticipated transients without scram (ATWS) in design extension condition (DECs). The present paper describes numerical analysis methodologies for event sequences studied in Japan and some numerical analyses of DECs to show the effectiveness of the passive shutdown system against a typical ATWS and severe accident mitigation measures for the IVR of molten core. For the passive shutdown capability, the numerical analysis has demonstrated the effectiveness of a self-actuated shutdown system against a severe ATWS event, for which the temperature response time was separately evaluated by a computational fluid dynamics (CFD) code. A recently developed debris-bed cooling analysis methodology coupled with a CFD code and a debris-bed module has successfully simulated a three-dimensional coolant flow field near the debris bed with the passive DHRS capability in order to demonstrate the debris-bed coolability on a core catcher.

Numerical investigations on the coolability and the re-criticality of a debris bed with the density-stratified configuration

Li, C.-Y.; Uchibori, Akihiro; Takata, Takashi; Pellegrini, M.*; Erkan, N.*; Okamoto, Koji*

Dai-25-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 4 Pages, 2021/07

The capability of stable cooling and avoiding re-criticality on the debris bed are the main issues for achieving IVR (In-Vessel Retention). In the actual situation, the debris bed is composed of mixed-density debris particles. Hence, when these mixed-density debris particles were launched to re-distribute, the debris bed would possibly form a density-stratified distribution. For the proper evaluation of this scenario, the multi-physics model of CFD-DEM-Monte-Carlo based neutronics is established to investigate the coolability and re-criticality on the heterogeneous density-stratified debris bed with considering the particle relocation. The CFD-DEM model has been verified by utilizing water injection experiments on the mixed-density particle bed in the first portion of this research. In the second portion, the coupled system of the CFD-DEM-Monte-Carlo based neutronics model is applied to reactor cases. Afterward, the debris particles' movement, debris particles' and coolant's temperature, and the k-eff eigenvalue are successfully tracked. Ultimately, the relocation and stratification effects on debris bed's coolability and re-criticality had been quantitatively confirmed.

Intuitive interactions for immersive data exploration of numerical simulation results

Tabata, Ginga*; Sakamoto, Naohisa*; Kawamura, Takuma

Proceedings of Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo 2020 (SNA + MC 2020), p.193 - 200, 2020/10

In interactive visualization/analysis, interactive operation of visualization results on the screen is an important technology that is directly linked to knowledge extraction. On the conventional 2D display, interactive operations such as moving the viewpoint and adjusting the visualization parameters were performed using the mouse. Then, the virtual reality (VR) technology such as CAVE system and head mounted display (HMD) is used for visualization and analysis, and the development of technology for interactively operating visualization result data in VR space has become one of the important issues in the visualization field. In this paper, we propose a technique to capture a real hand gesture by Leap Motion and intuitively change the viewpoint movement and visualization parameters in VR space by HMD. We asked four people to test the developed technology, and obtained a result that it was easy to change the viewpoint from the questionnaire on the operation feeling.

Performance evaluation of runtime data exploration framework based on in-situ particle based volume rendering

Kawamura, Takuma; Noda, Tomoyuki; Idomura, Yasuhiro

Supercomputing Frontiers and Innovations, 4(3), p.43 - 54, 2017/07

AA2017-0206.pdf:3.74MB

https://doi.org/10.14529/jsfi170302

We examine the performance of the in-situ data exploration framework based on the in-situ Particle Based Volume Rendering (In-Situ PBVR) on the latest many-core platform. In-Situ PBVR converts extreme scale volume data into small rendering primitive particle data via parallel Monte-Carlo sampling without costly visibility ordering. This feature avoids severe bottlenecks such as limited memory size per node and significant performance gap between computation and inter-node communication. In addition, remote in-situ data exploration is enabled by asynchronous file-based control sequences, which transfer the small particle data to client PCs, generate view-independent volume rendering images on client PCs, and change visualization parameters at runtime. In-Situ PBVR shows excellent strong scaling with low memory usage up to about 100k cores on the Oakforest-PACS, which consists of 8,208 Intel Xeon Phi7250 (Knights Landing) processors.

Study on In-Vessel Retention (IVR) of unprotected accident for fast reactor, 1; Overview of IVR evaluation in Anticipated Transient without Scram (ATWS)

Suzuki, Toru; Sogabe, Joji; Tobita, Yoshiharu; Sakai, Takaaki*; Nakai, Ryodai

Dai-21-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (USB Flash Drive), 4 Pages, 2016/06

A Preliminary evaluation of unprotected loss-of-flow accident for a prototype fast-breeder reactor

Suzuki, Toru; Tobita, Yoshiharu; Kawada, Kenichi; Tagami, Hirotaka; Sogabe, Joji; Matsuba, Kenichi; Ito, Kei; Ohshima, Hiroyuki

Nuclear Engineering and Technology, 47(3), p.240 - 252, 2015/04

https://doi.org/10.1016/j.net.2015.03.001

An Experimental study on heat transfer from a mixture of solid-fuel and liquid-steel during core disruptive accidents in Sodium-Cooled Fast Reactors

Kamiyama, Kenji; Konishi, Kensuke; Sato, Ikken; Toyooka, Junichi; Matsuba, Kenichi; Suzuki, Toru; Tobita, Yoshiharu; Pakhnits, A. V.*; Vityuk, V. A.*; Vurim, A. D.*; et al.

Proceedings of 10th International Topical Meeting on Nuclear Thermal Hydraulics, Operation and Safety (NUTHOS-10) (USB Flash Drive), 8 Pages, 2014/12

Utilization of the volume rendering with spherical sampling method to immersive VR system

Suzuki, Yoshio*; Takeshima, Yuriko; Ono, Nobuaki*; Koyamada, Koji*

Nihon Bacharu Riaritei Gakkai Rombunshi, 10(2), p.231 - 240, 2005/06

http://ci.nii.ac.jp/naid/110008728891

A volume rendering is widely used for intuitively understanding 3-dimensionaly distribution of physical quantities. When the quantities have a nest-like distribution, however, the inside distribution cannot be observed. As one of the solution, an immersive virtual reality (VR) system is useful, since the researcher can immersively observe the distribution by using such a system. However, a plane slice sampling method conventionally used in the volume rendering has a problem that the quality of visualized images deteriorates especially in the immersive VR system. To resolve the problem, a spherical surface sampling method is applied to the volume rendering in the immersive VR system. The quality of image and the display speed are compared between these two methods.

Visualization environment and its utilization in the ITBL building

Yasuhara, Yuko*

JAERI-Data/Code 2004-009, 31 Pages, 2004/12

JAERI-Data-Code-2004-009.pdf:8.42MB

In recent years, visualization techniques have become more and more important in various fields. Especially in scientific fields, a large amount of numerical output data crucially needs to be changed into visualized form, because computations have grown to larger and larger scales as well as have become more complicated, so that computed results must be intuitively comprehensible by using various visualization techniques like 3D or stereo image construction. In the visualization room in the ITBL building, a 3-screen Virtual Reality system, a Portable Virtual Reality system, a Mixed Reality system, and Visualization tools like alchemy etc. are installed for the above-mentioned use. These devices enable us to easily change numerical data into visualized images of a virtual reality world with the use of eye-glasses or a head-mount-display device. This article describes the visualization environment in the ITBL building, it's use, and the tasks to be solved.