Continuous data assimilation of large eddy simulation by lattice Boltzmann method and local ensemble transform Kalman filter (LBM-LETKF)

Hasegawa, Yuta; Onodera, Naoyuki; Asahi, Yuichi; Ina, Takuya; Imamura, Toshiyuki*; Idomura, Yasuhiro

Fluid Dynamics Research, 55(6), p.065501_1 - 065501_25, 2023/11

https://doi.org/10.1088/1873-7005/ad06bd

We investigate the applicability of the data assimilation (DA) to large eddy simulations (LESs) based on the lattice Boltzmann method (LBM). We carry out the observing system simulation experiment of a two-dimensional (2D) forced isotropic turbulence, and examine the DA accuracy of the nudging and the local ensemble transform Kalman filter (LETKF) with spatially sparse and noisy observation data of flow fields. The advantage of the LETKF is that it does not require computing spatial interpolation and/or an inverse problem between the macroscopic variables (the density and the pressure) and the velocity distribution function of the LBM, while the nudging introduces additional models for them. The numerical experiments with grids and 10% observation noise in the velocity showed that the root mean square error of the velocity in the LETKF with observation points ( of the total grids) and 64 ensemble members becomes smaller than the observation noise, while the nudging requires an order of magnitude larger number of observation points to achieve the same accuracy. Another advantage of the LETKF is that it well keeps the amplitude of the energy spectrum, while only the phase error becomes larger with more sparse observation. From these results, it was shown that the LETKF enables robust and accurate DA for the 2D LBM with sparse and noisy observation data.

Kinetic mass transfer behavior of Eu(III) in nitrilotriacetamide-impregnated polymer-coated silica particles

Miyagawa, Akihisa*; Hayashi, Naoki*; Kuzure, Yoshiaki*; Takahashi, Takumi*; Iwamoto, Hibiki*; Arai, Tsuyoshi*; Nagatomo, Shigenori*; Miyazaki, Yasunori; Hasegawa, Kenta; Sano, Yuichi; et al.

Bulletin of the Chemical Society of Japan, 96(7), p.671 - 676, 2023/07

https://doi.org/10.1246/bcsj.20230087

We investigated the distribution mechanism of Eu(III) in a single polymer-coated silica particle including nitrilotriacetamide (NTA) extractants known as HONTA and TOD2EHNTA. The present study provides a valuable approach for the evaluation and enhancement of the functionality of "single extractant-impregnated polymer-coated silica particle".

Experiment and numerical simulation of pulsation flow in single channel for Li-7 enrichment technology development by MCCCE method

Horiguchi, Naoki; Yoshida, Hiroyuki; Kitatsuji, Yoshihiro; Hasegawa, Makoto*; Kishimoto, Tadafumi*

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 7 Pages, 2023/05

From the viewpoint of energy security in Japan and reduction of the environmental load, continuous operation of light water reactors is essential. Since a pH adjuster with enriched Li-7 ions is required for water quality control on PWR, the development of Li-7 enrichment technology is one of the key issues. The multi-channel counter-current electrophoresis (MCCCE) method has been developed as the technology with a low environmental load. To put this method into practical use, it is necessary to understand Li-7 ion behavior in the channel flow and optimize the experimental condition to separate Li-7 and its isotope. In this paper, to understand Li-7 ion behavior in a single channel of the experimental apparatus, a numerical simulation method based on a computational fluid dynamics (CFD) code with a particle tracking method, TPFIT-LPT, was developed. In the method, the motion of multiple ions under the electric field was simulated as a particle with an added velocity by the electric field. The difference in the isotopes was represented by changing of the magnitude of the added velocity. We also considered that although it is impossible to measure the behavior of each ion, it is important to measure the flow velocity of the bulk fluid for the validation of the numerical simulation. We developed a lab-scale experimental apparatus in which the single channel of the actual apparatus was simplified to measure the flow velocity by Particle Image Velocimetry (PIV). We set a pulsation flow condition on the lab-scale experiment, which is one of difficult conditions for the numerical simulation, and measured the velocity. As the result, we confirmed that the pulsation flow was reproduced. We set the measured data as the inlet boundary condition of the numerical simulation and conducted it. As the numerical result, we confirmed the ions affected by the electric field moved upstream with pulsation. We also confirmed the effect of the electric field on the motion of the isotope.

Investigation of hydrogen superoxide adsorption during ORR on Pt/C catalyst in acidic solution for PEFC by high energy resolution XAFS

Yamamoto, Naoki*; Matsumura, Daiju; Hagihara, Yuto*; Tanaka, Kei*; Hasegawa, Yuta*; Ishii, Kenji*; Tanaka, Hirohisa*

Journal of Power Sources, 557, p.232508_1 - 232508_10, 2023/02

https://doi.org/10.1016/j.jpowsour.2022.232508

Parameter optimization for turbulent boundary layer generation using ensemble Kalman filter

Onodera, Naoyuki; Idomura, Yasuhiro; Hasegawa, Yuta; Nakayama, Hiromasa

Dai-36-Kai Suchi Ryutai Rikigaku Shimpojiumu Koen Rombunshu (Internet), 3 Pages, 2022/12

We have developed a wind simulation code named CityLBM to realize wind digital twins. Mesoscale wind conditions are given as boundary conditions in CityLBM by using a nudging data assimilation method. It is found that conventional approaches with constant nudging coefficients fail to reproduce turbulent intensity in long time simulations, where atmospheric stability conditions change significantly. We propose a dynamic parameter optimization method for the nudging coefficient based on an ensemble Kalman filter. CityLBM was validated against plume dispersion experiments in the complex urban environment of Oklahoma City. The nudging coefficient was updated to reduce the error of the turbulent intensity between the simulation and the observation. The mean error of velocity variance is reduced by 10% compared to the conventional nudging method with a constant nudging coefficient.

Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.

Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09

https://doi.org/10.1080/00223131.2022.2038301

In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.

Safety design philosophy of HTTR Heat Application Test Facility

Aoki, Takeshi; Shimizu, Atsushi; Iigaki, Kazuhiko; Okita, Shoichiro; Hasegawa, Takeshi; Mizuta, Naoki; Sato, Hiroyuki; Sakaba, Nariaki

JAEA-Technology 2022-011, 60 Pages, 2022/07

JAEA-Technology-2022-011.pdf:2.08MB

Japan Atomic Energy Agency is planning a High Temperature Engineering Test Reactor (HTTR) heat application test producing hydrogen with the HTTR which achieved the highest reactor outlet coolant temperature of 950C in the world to realize a massive, cost-effective and carbon-free hydrogen production technology utilizing a high temperature gas cooled reactor (HTGR). In the HTTR heat application test, it is required to establish its safety design for coupling a hydrogen production plant to HTGR through the licensing by the Nuclear Regulation Authority (NRA). A draft of a safety design philosophy for the HTTR heat application test facility was considered taking into account postulated events due to the plant modification and coupling of the hydrogen production plant based on the HTTR safety design which was authorized through the safety review of the NRA against New Regulatory Requirements. The safety design philosophy was examined to apply proven conventional chemical plant standards to the hydrogen production plant for ensuring public safety against disasters caused by high pressure gases. This report presents a result of a consideration on safety design philosophies regarding the reasonability and condition to apply the High Pressure Gas Safety Act for the hydrogen production plant, safety classifications, seismic design classification, identification of important safety system.

Parameter optimization for generating atmospheric boundary layers by using the locally mesh-refined lattice Boltzmann method

Onodera, Naoyuki; Idomura, Yasuhiro; Hasegawa, Yuta; Shimokawabe, Takashi*; Aoki, Takayuki*

Keisan Kogaku Koenkai Rombunshu (CD-ROM), 27, 4 Pages, 2022/06

We have developed a wind simulation code named CityLBM to realize wind digital twins. Mesoscale wind conditions are given as boundary conditions in CityLBM by using a nudging data assimilation method. It is found that conventional approaches with constant nudging coefficients fail to reproduce turbulent intensity in long time simulations, where atmospheric stability conditions change significantly. We propose a dynamic parameter optimization method for the nudging coefficient based on a particle filter. CityLBM was validated against plume dispersion experiments in the complex urban environment of Oklahoma City. The nudging coefficient was updated to reduce the error of the turbulent intensity between the simulation and the observation, and the atmospheric boundary layer was reproduced throughout the day.

GPU optimization of lattice Boltzmann method with local ensemble transform Kalman filter

Hasegawa, Yuta; Imamura, Toshiyuki*; Ina, Takuya; Onodera, Naoyuki; Asahi, Yuichi; Idomura, Yasuhiro

Proceedings of 13th Workshop on Latest Advances in Scalable Algorithms for Large-Scale Heterogeneous Systems (ScalAH22) (Internet), p.10 - 17, 2022/00

https://doi.org/10.1109/ScalAH56622.2022.00007

The ensemble data assimilation of computational fluid dynamics simulations based on the lattice Boltzmann method (LBM) and the local ensemble transform Kalman filter (LETKF) is implemented and optimized on a GPU supercomputer based on NVIDIA A100 GPUs. To connect the LBM and LETKF parts, data transpose communication is optimized by overlapping computation, file I/O, and communication based on data dependency in each LETKF kernel. In two dimensional forced isotropic turbulence simulations with the ensemble size of and the number of grid points of , the optimized implementation achieved speedup from the naive implementation, in which the LETKF part is not parallelized. The main computing kernel of the local problem is the eigenvalue decomposition (EVD) of real symmetric dense matrices, which is computed by a newly developed batched EVD in EigenG. The batched EVD in EigenG outperforms that in cuSolver, and speedup was achieved.

Tree cutting approach for domain partitioning on forest-of-octrees-based block-structured static adaptive mesh refinement with lattice Boltzmann method

Hasegawa, Yuta; Aoki, Takayuki*; Kobayashi, Hiromichi*; Idomura, Yasuhiro; Onodera, Naoyuki

Parallel Computing, 108, p.102851_1 - 102851_12, 2021/12

https://doi.org/10.1016/j.parco.2021.102851

The aerodynamics simulation code based on the lattice Boltzmann method (LBM) using forest-of-octrees-based block-structured local mesh refinement (LMR) was implemented, and its performance was evaluated on GPU-based supercomputers. We found that the conventional Space-Filling-Curve-based (SFC) domain partitioning algorithm results in costly halo communication in our aerodynamics simulations. Our new tree cutting approach improved the locality and the topology of the partitioned sub-domains and reduced the communication cost to one-third or one-fourth of the original SFC approach. In the strong scaling test, the code achieved maximum speedup at the performance of 2207 MLUPS (mega- lattice update per second) on 128 GPUs. In the weak scaling test, the code achieved 9620 MLUPS at 128 GPUs with 4.473 billion grid points, while the parallel efficiency was 93.4% from 8 to 128 GPUs.