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Ishizawa, Akihiro*; Idomura, Yasuhiro; Imadera, Kenji*; Kasuya, Naohiro*; Kanno, Ryutaro*; Satake, Shinsuke*; Tatsuno, Tomoya*; Nakata, Motoki*; Nunami, Masanori*; Maeyama, Shinya*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 92(3), p.157 - 210, 2016/03
The high-performance computer system Helios which is located at The Computational Simulation Centre (CSC) in The International Fusion Energy Research Centre (IFERC) started its operation in January 2012 under the Broader Approach (BA) agreement between Japan and the EU. The Helios system has been used for magnetised fusion related simulation studies in the EU and Japan and has kept high average usage rate. As a result, the Helios system has contributed to many research products in a wide range of research areas from core plasma physics to reactor material and reactor engineering. This project review gives a short catalogue of domestic simulation research projects. First, we outline the IFERC-CSC project. After that, shown are objectives of the research projects, numerical schemes used in simulation codes, obtained results and necessary computations in future.
Ito, Kei; Kunugi, Tomoaki*; Yamamoto, Yoshinobu*
Dai-21-Kai Suchi Ryutai Rikigaku Shimpojiumu Koen Yoshishu (CD-ROM), 5 Pages, 2007/12
To evaluate gas entrainment phenomena in fast reactor systems accurately, we are developing a high-precision gas-liquid two-phase flow simulation method on the unstructured mesh. As a part of the development, an appropriate formulation was newly derived based on collocated variables' distributions employed in our unstructured simulation method. This formulation satisfied a mechanical balance between surface tension and pressure gradient at interfacial region. A definition formula of each phase's velocity near interfacial mesh cell was also improved to calculate physically correct velocity. The improved method was verified by simulating a rising air bubble in static water. It was confirmed that the new formulation eliminated unphysical interfacial behaviors induced by inappropriate formulations, and led similar air bubble shapes with experimental data both on the structured and the unstructured meshes.
Ito, Kei; Yamamoto, Yoshinobu*; Kunugi, Tomoaki*
Proceedings of 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-12) (CD-ROM), 15 Pages, 2007/09
For the purpose of direct numerical simulations of gas entrainment in fast breeder reactors, we are developing a high-precision seamless physical simulator based on computational scientific approaches. An unstructured mesh partitioning method was employed in this study and a high-precision calculation method for gas-liquid two-phase flow on the unstructured mesh was developed on the basis of the MARS formulated on a structured mesh. As the result of the verification, it was confirmed that the developed method has comparable or higher calculation accuracy compared to conventional methods. In addition, a correction method was introduced to the advection term of the volume fraction transport equation to improve volume conservation. The correction method led higher calculation accuracy on the unstructured mesh compared to the original method. Errors in a surface tension calculation were also estimated and the reconstructed distance function method showed the most accurate result.
Ito, Kei; Yamamoto, Yoshinobu*; Kunugi, Tomoaki*
no journal, ,
no abstracts in English
Ito, Kei; Yamamoto, Yoshinobu*; Kunugi, Tomoaki*
no journal, ,
For the purpose of direct simulation of gas entrainment (GE) phenomena in a sodium-cooled fast reactors, we are developing a high-accuracy seamless physical simulator based on computational scientific methods. In this study, a high-accuracy calculation method for gas-liquid two-phase flow on unstructured mesh has been developed. In this paper, formulations of the calculation method and calculation results of the verification works solving slotted-disk rotation problem are presented. As the verification result, it became clear that the present method had comparable or higher calculation accuracy comparing with conventional high-accuracy methods. In addition, a correction method was introduced to the advection term of the volume fraction transport equation to improve volume preservation characteristics of each phase. This correction method could lead higher calculation accuracy on unstructured mesh comparing with the original method (without correction method).
Ito, Kei; Yamamoto, Yoshinobu*; Kunugi, Tomoaki*
no journal, ,
For numerical evaluations of gas entrainment phenomena in sodium-cooled fast breeder reactors, numerical simulation methods have been developed. This numerical simulation methods are formulated on unstructured mehses to be applicable to numerical simulations in complicated geometries. In this report, formulations and verifications of high-precision calculation methods for two-phase flows on unstructured meshes are presented.
