Tohoku University · 공학
Taku Nonomura 교수의 연구실은 초음속 유동 및 유동유도 음향장의 수치 해석을 핵심으로 하며, 고정밀 수치 해법과 동적 모드 분해(DMD) 기반의 시스템 식별 기법을 융합한 연구를 수행하고 있습니다. 특히, 고차수 가중형 비선형 보간법(WCNS), WENO 스킴의 자유류 유지 기법, 그리고 칼만 필터 기반 동적 모드 분석(KFDMD, EKFDMD)을 활용해 복잡한 유동 현상의 정확한 해석과 노이즈 제거를 추구합니다. 응용 분야로는 항공우주 분야의 소음 저감 설계 및 실시간 유동 제어 기술 개발이 포함됩니다.
표시된 성과는 수집된 데이터 기준으로 산출되며, 일부 차이가 있을 수 있습니다.
This paper presents a computational study of the flow and flow-induced acoustic fields of a supersonic jet impinging on an inclined flat plate. For the numerical simulations, we solved three-dimensional compressible Navier-Stokes equations with a modified weighted compact nonlinear scheme. We analyzed the simulation results mainly from the viewpoint of the acoustic emission and propagation mechanism, and we investigated the acoustic field characteristics such as directivity, their spectra, and a
A new technique for a finite-difference weighted essentially nonoscillatory scheme (WENO) on curvilinear grids to preserve freestream is introduced. This technique first divides the standard finite-difference WENO into two parts: (1) a consistent central difference part and (2) a numerical dissipation part. For the consistent central difference part, the conservative metric technique is directly adopted. For the numerical dissipation part, it is proposed that the metric term should be frozen for
A new dynamic mode decomposition (DMD) method is introduced for simultaneous system identification and denoising in conjunction with the adoption of an extended Kalman filter algorithm. The present paper explains the extended-Kalman-filter-based DMD (EKFDMD) algorithm which is an online algorithm for dataset for a small number of degree of freedom (DoF). It also illustrates that EKFDMD requires significant numerical resources for many-degree-of-freedom (many-DoF) problems and that the combinatio
A novel dynamic mode decomposition (DMD) method based on a Kalman filter is proposed. This paper explains the fast algorithm of the proposed Kalman filter DMD (KFDMD) in combination with truncated proper orthogonal decomposition for many-degree-of-freedom problems. Numerical experiments reveal that KFDMD can estimate eigenmodes more precisely compared with standard DMD or total least-squares DMD (tlsDMD) methods for the severe noise condition if the nature of the observation noise is known, thou
The coefficients of higher order weighted compact nonlinear scheme (WCNS) and the resolutions of the family of higher order WCNS are investigated. The coefficients of seventh and ninth order WCNS are calculated by using MATHEMATICA. Seventh and ninth WCNS can resolve the discontinuity without numerical oscillations as well as fifth order WCNS. Seventh and Ninth order WCNS have the higher resolution on the one-dimensional shock-entropy interaction problem with few grid points than fifth order WCN
The effects of plate angle on acoustic waves from a supersonic jet impinging on an inclined flat plate at angles of 30, 45, and 60 deg are numerically investigated. Three-dimensional compressible Navier–Stokes equations are solved using the modified weighted compact nonlinear scheme. Similar to previous studies, the acoustic fields indicate that there are at least three types of acoustic waves in all of the cases considered herein: 1) Mach waves generated from the shear layer of the main jet, 2)
