Numerical Experiment of Transient and Steady Characteristics of Ultrasonic-Measurement-Integrated Simulation in Three-Dimensional Blood Flow Analysis

Funamoto, Kenichi; Hayase, Toshiyuki; Saijo, Yoshifumi; Yambe, Tomoyuki

doi:10.1007/s10439-008-9600-2

Cited by 13 publications

(21 citation statements)

References 24 publications

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“…This relation agrees with the empirical relation obtained in a former study [25]. In summary, the destabilization phenomenon of existing MI simulation is ascribed to the fact that a large feedback signal in the source term determines the leading term of the numerator of the coefficient for the successive change in the iterative calculation, and, therefore, divergence occurs with a coefficient larger than 1 or with a feedback gain larger than the critical value.…”

Section: Stabilizationsupporting

confidence: 80%

“…The transient characteristics of the UMI simulation were evaluated by the time constant or equivalently by the frequency response to the oscillating flow, and the steady characteristics were evaluated by the steady state error of the velocity vectors in an aneurysm. Velocity error vectors against the standard solution are shown in Figure 17 [25]. In the initial state, the result is the same as that of the ordinary simulation with large error vectors.…”

Section: Blood Flowssupporting

confidence: 63%

“…An example of UMI simulation with feedback from real color Doppler measurement also showed good agreement with measurement ( Figure 16). Ultrasonic-measurement-integrated (UMI) simulation to reproduce three-dimensional steady and unsteady blood flows in an aneurysmal aorta with realistic boundary conditions was investigated [25] [30]. The transient characteristics of the UMI simulation were evaluated by the time constant or equivalently by the frequency response to the oscillating flow, and the steady characteristics were evaluated by the steady state error of the velocity vectors in an aneurysm.…”

Section: Blood Flowsmentioning

confidence: 99%

“…Figure 3 shows the critical feedback gains with the computational time step plotted for the results of UMI simulation for blood flow in an aneurismal aorta (Case 1) [25] [30], magnetic-resonance measurement-integrated (MR-MI) blood flow simulation in a cerebral aneurism (Case 2) [26], and MI simulation for the turbulent flow in a square duct (Case 4). Theoretical values for the critical feedback gain were obtained from Equation (17).…”

Section: Stabilizationmentioning

confidence: 99%

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A Review of Measurement-Integrated Simulation of Complex Real Flows

Hayase¹

2015

JFCMV

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In spite of the inherent difficulty, reproducing the exact structure of real flows is a critically important issue in many fields, such as weather forecasting or feedback flow control. 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 (4D-Var) 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 (CFD) scheme is used as a mathematical model of the physical system instead of a small dimensional linear dynamical system usually used in state observers. A large dimensional nonlinear CFD model makes it possible to accurately reproduce real flows for properly designed feedback signals. This review article surveys the theoretical formulations and applications of MI simulation. Formulations of MI simulation are presented, including governing equations of a flow field observer, those of a linearized error dynamics describing the convergence of the observer, and stabilization of the numerical scheme, which is important in implementation of MI simulation. Applications of MI simulation are presented ranging from fundamental turbulent flows in pipes and Karman vortices in a wind tunnel to clinical application in diagnosis of blood flows in a human body.

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Section: Stabilizationsupporting

confidence: 80%

Section: Blood Flowssupporting

confidence: 63%

Section: Blood Flowsmentioning

confidence: 99%

Section: Stabilizationmentioning

confidence: 99%

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A Review of Measurement-Integrated Simulation of Complex Real Flows

Hayase¹

2015

JFCMV

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“…In our previous studies, a two-dimensional UMI simulation using real ultrasound color Doppler images was conducted [19]. The transient and steady characteristics of UMI simulation and the efficiency of feedback to reproduce unsteady threedimensional hemodynamics were investigated by numerical experiments [21][22][23]. Those studies revealed that the UMI simulation improved computational accuracy in comparison with the ordinary simulation, making the computational velocity vector field approach that of a model solution of real blood flow.…”

Section: Introductionmentioning

confidence: 95%

Reproduction of pressure field in ultrasonic‐measurement‐integrated simulation of blood flow

Funamoto

Hayase

2012

Numer Methods Biomed Eng

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Ultrasonic-measurement-integrated (UMI) simulation of blood flow is used to analyze the velocity and pressure fields by applying feedback signals of artificial body forces based on differences of Doppler velocities between ultrasonic measurement and numerical simulation. Previous studies have revealed that UMI simulation accurately reproduces the velocity field of a target blood flow, but that the reproducibility of the pressure field is not necessarily satisfactory. In the present study, the reproduction of the pressure field by UMI simulation was investigated. The effect of feedback on the pressure field was first examined by theoretical analysis, and a pressure compensation method was devised. When the divergence of the feedback force vector was not zero, it influenced the pressure field in the UMI simulation while improving the computational accuracy of the velocity field. Hence, the correct pressure was estimated by adding pressure compensation to remove the deteriorating effect of the feedback. A numerical experiment was conducted dealing with the reproduction of a synthetic three-dimensional steady flow in a thoracic aneurysm to validate results of the theoretical analysis and the proposed pressure compensation method. The ability of the UMI simulation to reproduce the pressure field deteriorated with a large feedback gain. However, by properly compensating the effects of the feedback signals on the pressure, the error in the pressure field was reduced, exhibiting improvement of the computational accuracy. It is thus concluded that the UMI simulation with pressure compensation allows for the reproduction of both velocity and pressure fields of blood flow.

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Inverse problems in blood flow modeling: A review

Nolte

Bertoglio

2022

Numer Methods Biomed Eng

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Mathematical and computational modeling of the cardiovascular system is increasingly providing non‐invasive alternatives to traditional invasive clinical procedures. Moreover, it has the potential for generating additional diagnostic markers. In blood flow computations, the personalization of spatially distributed (i.e., 3D) models is a key step which relies on the formulation and numerical solution of inverse problems using clinical data, typically medical images for measuring both anatomy and function of the vasculature. In the last years, the development and application of inverse methods has rapidly expanded most likely due to the increased availability of data in clinical centers and the growing interest of modelers and clinicians in collaborating. Therefore, this work aims to provide a wide and comparative overview of literature within the last decade. We review the current state of the art of inverse problems in blood flows, focusing on studies considering fully dimensional fluid and fluid–solid models. The relevant physical models and hemodynamic measurement techniques are introduced, followed by a survey of mathematical data assimilation approaches used to solve different kinds of inverse problems, namely state and parameter estimation. An exhaustive discussion of the literature of the last decade is presented, structured by types of problems, models and available data.

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Numerical Experiment of Transient and Steady Characteristics of Ultrasonic-Measurement-Integrated Simulation in Three-Dimensional Blood Flow Analysis

Cited by 13 publications

References 24 publications

A Review of Measurement-Integrated Simulation of Complex Real Flows

A Review of Measurement-Integrated Simulation of Complex Real Flows

Reproduction of pressure field in ultrasonic‐measurement‐integrated simulation of blood flow

Inverse problems in blood flow modeling: A review

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