Newsletter  2021.11  Index

Theme : "Mechanical Engineering Congress, 2021 Japan (MECJ-21)” Preface Masaaki MOTOZAWA, Hideo MORI Turbulence of viscoelastic fluid-from practical examples to turbulent coherent structure Yasuo KAWAGUCHI (Tokyo University of Science) Integration method of measurement and simulation in flow analysis and its applications Toshiyuki HAYASE (Tohoku University) Workshop on Experimental Fluid Dynamics (EFD) Chair: Shouichiro IIO (Shinshu University), Masaki FUCHIWAKI(Kyushu Institute of Technology), Ayumu INASAWA(Tokyo Metropolitan University), and Satoshi KIKUCHI (Gifu University) The Aerodynamic Noise not Made Clear With Acoustic Wind-tunnel Yoshiyuki MARUTA (Chuo University) Analysis of the flow-induced noise with the Extended Proper Orthogonal Decomposition Osamu TERASHIMA, Reon NISHIKAWA (Toyama Prefectural University), and Miyu OKUNO (Kanazawa University) Fan Noise Characteristics and Reduction Hidechito HAYASHI (Nagasaki University)

 

Integration method of measurement and simulation in flow analysis and its applications

Toshiyuki HAYASE Tohoku University

Abstract

In order to obtain information on real flows, extensive studies have been carried out on methodology to integrate measurement and simulation, for example, the four-dimensional variational data assimilation method or the state estimator such as the Kalman filter or the state observer. Measurement-integrated (MI) simulation is a state observer in which a computational fluid dynamics scheme is used as a mathematical model of the physical system in state observers. In MI simulation the computational result of the model flows converges to the state of the real flow by the effect of the feedback signal or the artificial force to compensate the difference between the model and real flows. Figure 1 shows the hybrid wind tunnel by which the Kalman vortex in a wind tunnel is analyzed by the server in real time. As shown in Fig. 2 the flow structure is properly reproduced by MI simulation including the phase of the oscillation.   Medical application of MI simulation is shown in Fig. 3. In two-dimensional ultrasonic-measurement-integrated (UMI) blood flow analysis system, blood flow simulation is performed by applying the feedback signal based on measurement of the Doppler velocity, velocity component of the blood flow along the ultrasound beam. As shown in Fig. 4 (b) complex blood flow in a carotid artery is properly reproduced in MI simulation while a simple Poiseuille flow was obtained by an ordinary simulation in Fig. 4 (a). By comparing the Doppler velocity measured values with the calculated values, the error of the Doppler velocity was reduced by about 1/3 compared with the ordinary simulation in the UMI simulation. These results show that complex blood flow fields can be reproduced with high accuracy by UMI simulation.

Key words

Computational Fluid dynamics, State observer, Measurement-integrated simulation, Karman Vortex, Blood Flow

Figures

Fig. 1 Real-time analysis of Karman vortices with a hybrid wind tunnel

Fig. 2 Streak lines obtained with (a) experiment and (b) MI simulation

Fig. 3 Two-dimensional ultrasonic-measurement-integrated (UMI) blood flow analysis system
Fig. 4 Analysis results of blood flow in a carotid artery with (a) ordinary simulation and (b) UMI simulation