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第1回直交格子CFDワークショップ (2020年9月30日. オンライン開催), The 1st Workshop on Cartesian Grid-based CFD (September 30, 2020. Online Conference), The hierarchical cartesian grid method with immersed boundary method can realize automatic grid generation for very complicated geometries such as actual configuration of the aircraft. In this method, the geometry shape needs to be modeled by an algorithm and the analysis accuracy of this method has not been fully validated compared to traditional analysis methods using the body-fitted grid. Therefore, analysis accuracy of hierarchical cartesian grid method with immersed boundary method is studied fur two-dimensional basic geometries., 注記: 流体力学講演会/航空宇宙数値シミュレーション技術シンポジウム2020オンライン内で実施, 形態: カラー図版あり, Note: Workshop was held in Fluid Dynamics Conference / Aerospace Numerical Simulation Symposium 2020 Online, Physical characteristics: Original contains color illustrations, 資料番号: AA2030018002, レポート番号: JAXA-SP-20-006

流体力学講演会/航空宇宙数値シミュレーション技術シンポジウム2020オンライン (2020年9月28日-30日. 日本航空宇宙学会 : 宇宙航空研究開発機構(JAXA)オンライン会議), Fluid Dynamics Conference / Aerospace Numerical Simulation Symposium 2020 Online (September 28-30, 2020. The Japan Society for Aeronautical and Space Sciences : Japan Aerospace Exploration Agency (JAXA), Online meeting), In the immersed boundary method used in the hierarchical cartesian grid method, the geometry shape needs to be modeled by an algorithm, etc., unlike the geometry-adaptive grid using general curvilinear coordinates, and it is necessary to discuss the analysis accuracy near the geometry surface. In this paper, we will report the verification results of the analysis accuracy on the surface of the two-dimensional thin airfoil (NACA4402)., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA2030013023, レポート番号: JAXA-SP-20-008

Fifth Aerodynamics Prediction Challenge (APC-V) ワークショップ (2019年7月1日. 早稲田大学早稲田キャンパス国際会議場), 新宿区, 東京, Fifth Aerodynamics Prediction Challenge workshop (APC-V) (July 1, 2019. International Conference Center, Waseda University), Shinjuku-ku, Tokyo, Japan, 著者名の誤記: Yoshihara, Tamaki, 注記: 第51回流体力学講演会/第37回航空宇宙数値シミュレーション技術シンポジウム内で実施, 形態: カラー図版あり, The clerical error of an author's name: Yoshihara, Tamaki, Note: Workshop was held in 51st Fluid Dynamics Conference / 37th Aerospace Numerical Simulation Symposium, Physical characteristics: Original contains color illustrations, 資料番号: AA1930013005, レポート番号: JAXA-SP-19-008

Fifth Aerodynamics Prediction Challenge (APC-V) ワークショップ (2019年7月1日. 早稲田大学早稲田キャンパス国際会議場), 新宿区, 東京, Fifth Aerodynamics Prediction Challenge workshop (APC-V) (July 1, 2019. International Conference Center, Waseda University), Shinjuku-ku, Tokyo, Japan, 著者名の誤記: Yoshihara, Tamaki, 注記: 第51回流体力学講演会/第37回航空宇宙数値シミュレーション技術シンポジウム内で実施, 形態: カラー図版あり, The clerical error of an author's name: Yoshihara, Tamaki, Note: Workshop was held in 51st Fluid Dynamics Conference / 37th Aerospace Numerical Simulation Symposium, Physical characteristics: Original contains color illustrations, 資料番号: AA1930013004, レポート番号: JAXA-SP-19-008

第51回流体力学講演会/第37回航空宇宙数値シミュレーション技術シンポジウム (2019年7月1日-3日. 早稲田大学早稲田キャンパス国際会議場), 新宿区, 東京, 51st Fluid Dynamics Conference / the 37th Aerospace Numerical Simulation Symposium (July 1-3, 2019. International Conference Center, Waseda University), Shinjuku-ku, Tokyo, Japan, We are developing a high-speed and high-precision turbulent flow solver for high Reynolds number flows for the post-K computer. It is based on the hierarchical cartesian grid method and immersed boundary method, which can realize high-speed analysis, and the LES wall model, which can realize high-precision LES analysis of high Reynolds number flows. In this presentation, the outline of the program, especially the key technology for realizing high-speed analysis, is presented., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA1930011014, レポート番号: JAXA-SP-19-007

Fourth Aerodynamics Prediction Challenge (APC-IV) ワークショップ (2018年7月4日. 宮崎市民プラザ), 宮崎市, 宮崎, 注記: 第50回流体力学講演会/第36回航空宇宙数値シミュレーション技術シンポジウム内で実施, 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA1830030003, レポート番号: JAXA-SP-18-008

Fourth Aerodynamics Prediction Challenge (APC-IV) ワークショップ (2018年7月4日. 宮崎市民プラザ), 宮崎市, 宮崎, 注記: 第50回流体力学講演会/第36回航空宇宙数値シミュレーション技術シンポジウム内で実施, 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA1830030004, レポート番号: JAXA-SP-18-008

第50回流体力学講演会/第36回航空宇宙数値シミュレーション技術シンポジウム (2018年7月4日-6日. 宮崎市民プラザ), 宮崎市, 宮崎, 50th Fluid Dynamics Conference /the 36th Aerospace Numerical Simulation Symposium (July 4-6, 2018. Miyazaki Citizen's Plaza), Miyazaki, Japan, Cartesian grid method is suitable for aerodynamic design of aircraft because its fast, automatic and robust grid generation alleviates labor and time in numerical simulation. To improve simulation accuracy near wall in Cartesian CFD, we have proposed the method which extends wall adjacent fluid cells to the wall. Thus, conservation laws are satisfied, and wall aligned grid can be generated without complicated exception handling on arbitrary shaped objects. The objective of the present study is to examine the applicability of our method to grid generation around 3D complex geometries. The grid around DLR-F4 is generated and shape reconstruction quality is examined. In addition, inviscid flow calculations around NACA0012 and ONERA M6 are conducted., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA1830029019, レポート番号: JAXA-SP-18-005

第49回流体力学講演会/第35回航空宇宙数値シミュレーション技術シンポジウム (2017年6月28日-30日. 国立オリンピック記念青少年総合センター), 渋谷区, 東京, 49th Fluid Dynamics Conference /the 35th Aerospace Numerical Simulation Symposium (June 28-30, 2017. National Olympics Memorial Youth Center), Shibuya-ku, Tokyo, Japan, To simulate flows around complex geometries, an improvement on the Cartesian-grid-based flow solver UTCart is proposed, which enables UTCart to handle a grid with variable cell sizes on the wall. UTCart uses an immersed boundary method with a wall function for the wall boundary condition in turbulent flow simulations. The boundary condition requires a cutoff distance that is defined as the grid size assigned at the nearest wall multiplied by a constant. A large computational effort was needed to determine the cutoff distance because every cell in the computational domain must detect the nearest wall. Thus, a new method based on an advection equation to calculate the cutoff distance is developed. Using UTCart, turbulent flows around the JAXA high-lift configuration standard model are simulated. The surface features, including the small gaps between the wing and the flap, are well resolved in the generated grid that has approximately 110 million cells. In the computational results, the lift coefficients and the surface pressure coefficients show a good agreement with the experimental data, especially at the low angles of attack., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA1730011023, レポート番号: JAXA-SP-17-004

Third Aerodynamics Prediction Challenge (APC-III) ワークショップ (2017年6月28日. 国立オリンピック記念青少年総合センター), 渋谷区, 東京, 注記: 第49回流体力学講演会/第35回航空宇宙数値シミュレーション技術シンポジウム内で実施, 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA1730007005, レポート番号: JAXA-SP-17-001

Second Aerodynamics Prediction Challenge (APC-II) ワークショップ (2016年7月6日. 金沢歌劇座), 金沢市, 石川, 注記: 第48回流体力学講演会/第34回航空宇宙数値シミュレーション技術シンポジウム内で実施, 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA1630028010, レポート番号: JAXA-SP-16-004

First Aerodynamics Prediction Challenge (APC-I) ワークショップ (2015年7月3日. 東京大学生産技術研究所), 東京, Aerodynamic Prediction Challenge workshop (APC-I) (July 3, 2015. Institute of Industrial Science, the University of Tokyo), Tokyo, Japan, 注記: 第47回流体力学講演会/第33回航空宇宙数値シミュレーション技術シンポジウム内で実施, 形態: カラー図版あり, Note: Workshop was held in 47th Fluid Dynamics Conference / 33nd Aerospace Numerical Simulation Symposium, Physical characteristics: Original contains color illustrations, 資料番号: AA1530033015, レポート番号: JAXA-SP-15-005

第46回流体力学講演会/第32回航空宇宙数値シミュレーション技術シンポジウム (2014年7月3日-4日. 弘前文化センター), 弘前市, 青森県, 46th Fluid Dynamics Conference / 32nd Aerospace Numerical Simulation Symposium (July 3-4, 2014. Hirosaki Bunka Center), Hirosaki, Aomori, Japan, In this paper, a new higher-order flux quadrature scheme for finite-volume methods (FVM) is proposed. The scheme is especially for unstructured Cartesian grids; therefore only the information (values and its spatial gradients) of the two cells which shares the face is used to calculate the flux. On the FVM, cell-averaged values are updated in each cell. The values are interpolated onto the cell-interface to calculate numerical flux, and then the flux is integrated over the cell-interface. The spatial accuracy of the entire scheme depends on the accuracy of both the variable interpolation and the flux quadrature. In the conventional flux quadrature, the flux evaluated at one point on each face of the cell is multiplied with the area of the face, but the accuracy is only second-order. In order to enhance the accuracy of the quadrature, at first, the error terms of the conventional scheme are clarified. The error term is represented with the variables and its gradient value along the face, thus can be calculated using the value of the both cell sharing the face. Adding this error term as a modifying flux to the conventional second-order integrated flux, the accuracy of quadrature is enhanced to fourth-order. The new scheme is implemented in the verification problems on Burgers and Euler equations on the FVM framework, and the results show fourth-order convergence correctly., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA1530023017, レポート番号: JAXA-SP-14-010