scholarly journals Validation of a one-dimensional model of the systemic arterial tree

2009 ◽  
Vol 297 (1) ◽  
pp. H208-H222 ◽  
Author(s):  
Philippe Reymond ◽  
Fabrice Merenda ◽  
Fabienne Perren ◽  
Daniel Rüfenacht ◽  
Nikos Stergiopulos
Keyword(s):  
Constitutive Law ◽  
Distributed Model ◽  
Arterial Tree ◽  
One Dimensional ◽  
Continuity Equations ◽  
Nonlinear Viscoelastic ◽  
Model Predictions ◽  
The One ◽  
D Model ◽  
Systemic Arterial Tree

A distributed model of the human arterial tree including all main systemic arteries coupled to a heart model is developed. The one-dimensional (1-D) form of the momentum and continuity equations is solved numerically to obtain pressures and flows throughout the systemic arterial tree. Intimal shear is modeled using the Witzig-Womersley theory. A nonlinear viscoelastic constitutive law for the arterial wall is considered. The left ventricle is modeled using the varying elastance model. Distal vessels are terminated with three-element windkessels. Coronaries are modeled assuming a systolic flow impediment proportional to ventricular varying elastance. Arterial dimensions were taken from previous 1-D models and were extended to include a detailed description of cerebral vasculature. Elastic properties were taken from the literature. To validate model predictions, noninvasive measurements of pressure and flow were performed in young volunteers. Flow in large arteries was measured with MRI, cerebral flow with ultrasound Doppler, and pressure with tonometry. The resulting 1-D model is the most complete, because it encompasses all major segments of the arterial tree, accounts for ventricular-vascular interaction, and includes an improved description of shear stress and wall viscoelasticity. Model predictions at different arterial locations compared well with measured flow and pressure waves at the same anatomical points, reflecting the agreement in the general characteristics of the “generic 1-D model” and the “average subject” of our volunteer population. The study constitutes a first validation of the complete 1-D model using human pressure and flow data and supports the applicability of the 1-D model in the human circulation.

Validation of a patient-specific one-dimensional model of the systemic arterial tree

2011 ◽  
Vol 301 (3) ◽  
pp. H1173-H1182 ◽  
Author(s):  
Philippe Reymond ◽  
Yvette Bohraus ◽  
Fabienne Perren ◽  
Francois Lazeyras ◽  
Nikos Stergiopulos
Keyword(s):  
Arterial Wall ◽  
Specific Model ◽  
Constitutive Law ◽  
Distributed Model ◽  
Patient Specific ◽  
Dimensional Model ◽  
Arterial Tree ◽  
One Dimensional ◽  
Flow Waveforms ◽  
Systemic Arterial Tree

The aim of this study is to develop and validate a patient-specific distributed model of the systemic arterial tree. This model is built using geometric and hemodynamic data measured on a specific person and validated with noninvasive measurements of flow and pressure on the same person, providing thus a patient-specific model and validation. The systemic arterial tree geometry was obtained from MR angiographic measurements. A nonlinear viscoelastic constitutive law for the arterial wall is considered. Arterial wall distensibility is based on literature data and adapted to match the wave propagation velocity of the main arteries of the specific subject, which were estimated by pressure waves traveling time. The intimal shear stress is modeled using the Witzig-Womersley theory. Blood pressure is measured using applanation tonometry and flow rate using transcranial ultrasound and phase-contrast-MRI. The model predicts pressure and flow waveforms in good qualitative and quantitative agreement with the in vivo measurements, in terms of wave shape and specific wave features. Comparison with a generic one-dimensional model shows that the patient-specific model better predicts pressure and flow at specific arterial sites. These results obtained let us conclude that a patient-specific one-dimensional model of the arterial tree is able to predict well pressure and flow waveforms in the main systemic circulation, whereas this is not always the case for a generic one-dimensional model.

One Dimensional Model of the Systemic Arterial Tree Including Cerebral Circulation

2007 ◽  
Author(s):  
Philippe Reymond ◽  
Fabrice Merenda ◽  
Fabienne Perren ◽  
Daniel Rüfenacht ◽  
Nikos Stergiopulos
Keyword(s):  
Cerebral Circulation ◽  
Cerebral Arteries ◽  
Distributed Model ◽  
Dimensional Model ◽  
Heart Model ◽  
Arterial Tree ◽  
One Dimensional ◽  
Distributed Models ◽  
The Past ◽  
Systemic Arterial Tree

The aim of this study is to develop a distributed model of the entire systemic arterial tree, coupled to a heart model and including a detailed description of the cerebral arteries. Distributed models of the arterial tree have been studied extensively in the past (Avolio [1]; Cassot et al [2]; Meister [3]; Schaaf and Abbrecht [4]; Stergiopulos et al [5]; Westerhof et al [6]; Zagzoule and Marc-Vergnes [7]), however, no model has been developed so far that offers a physiologically relevant coupling to the heart and includes the entire cerebral artery network.

Toward a noninvasive subject-specific estimation of abdominal aortic pressure

2008 ◽  
Vol 295 (3) ◽  
pp. H1156-H1164 ◽  
Author(s):  
Carl-Johan Thore ◽  
Jonas Stålhand ◽  
Matts Karlsson
Keyword(s):  
Aortic Pressure ◽  
Processing Technique ◽  
Distributed Model ◽  
Specific Information ◽  
Peripheral Artery ◽  
Tree Model ◽  
Signal Processing Technique ◽  
Arterial Tree ◽  
One Dimensional ◽  
Abdominal Aortic

A method for estimation of central arterial pressure based on linear one-dimensional wave propagation theory is presented in this paper. The equations are applied to a distributed model of the arterial tree, truncated by three-element windkessels. To reflect individual differences in the properties of the arterial trees, we pose a minimization problem from which individual parameters are identified. The idea is to take a measured waveform in a peripheral artery and use it as input to the model. The model subsequently predicts the corresponding waveform in another peripheral artery in which a measurement has also been made, and the arterial tree model is then calibrated in such a way that the computed waveform matches its measured counterpart. For the purpose of validation, invasively recorded abdominal aortic, brachial, and femoral pressures in nine healthy subjects are used. The results show that the proposed method estimates the abdominal aortic pressure wave with good accuracy. The root mean square error (RMSE) of the estimated waveforms was 1.61 ± 0.73 mmHg, whereas the errors in systolic and pulse pressure were 2.32 ± 1.74 and 3.73 ± 2.04 mmHg, respectively. These results are compared with another recently proposed method based on a signal processing technique, and it is shown that our method yields a significantly ( P < 0.01) lower RMSE. With more extensive validation, the method may eventually be used in clinical practice to provide detailed, almost individual, specific information as a valuable basis for decision making.

Validation of 1D Model of the Systemic Arterial Tree Including the Cerebral Circulation

2008 ◽  
Author(s):  
Philippe Reymond ◽  
Fabrice Merenda ◽  
Fabienne Perren ◽  
Daniel Rüfenacht ◽  
Nikos Stergiopulos
Keyword(s):  
Cerebral Circulation ◽  
Cerebral Arteries ◽  
Distributed Model ◽  
Heart Model ◽  
Arterial Tree ◽  
Distributed Models ◽  
The Past ◽  
1D Model ◽  
Systemic Arterial Tree

The aim of this study is to develop a distributed model of the entire systemic arterial tree, coupled to a heart model and including a detailed description of the cerebral arteries. Distributed models of the arterial tree have been studied extensively in the past (Avolio [1], Stergiopulos et al [2], Westerhof et al [3]), however, no model has been developed so far that offers a physiologically relevant coupling to the heart and includes the entire cerebral arterial tree.

P8.13 A 1-D MODEL OF THE SYSTEMIC ARTERIAL TREE IN MICE

2014 ◽  
Vol 8 (4) ◽  
pp. 154
Author(s):  
L. Aslanidou ◽  
B. Trachet ◽  
P. Reymond ◽  
P. Segers ◽  
N. Stergiopulos
Keyword(s):  
Arterial Tree ◽  
D Model ◽  
Systemic Arterial Tree

One-Dimensional and Two-Dimensional Estimates of Abutment Scour Prediction Variables

1998 ◽  
Vol 1647 (1) ◽  
pp. 18-26 ◽  
Author(s):  
Terry W. Sturm ◽  
Antonis Chrisochoides
Keyword(s):  
Vertical Wall ◽  
Two Dimensional ◽  
One Dimensional ◽  
Bridge Abutment ◽  
Overbank Flow ◽  
Bridge Approach ◽  
Surface Profiles ◽  
Abutment Scour ◽  
The One ◽  
D Model

An experimental study of the estimation of hydraulic parameters needed in bridge abutment scour formulas is presented. Two different compound channel geometries are studied with rough floodplains in shallow overbank flow. Vertical-wall and spill-through abutment shapes are included in the study, with the abutment face located on the floodplain for various embankment lengths. Water surface profiles and velocity distributions are measured and compared with predictions made by the one-dimensional (1-D) model WSPRO and a two-dimensional k-ε turbulence model developed in previous research. The results show that a 1-D model can predict scour parameters reasonably well in the bridge approach section but not in the bridge contraction section.

scholarly journals Transition from Diffusion to Wave Propagation in Fractional Jeffreys-Type Heat Conduction Equation

2020 ◽  
Vol 4 (3) ◽  
pp. 32
Author(s):  
Emilia Bazhlekova ◽  
Ivan Bazhlekov
Keyword(s):  
Heat Conduction ◽  
Fundamental Solution ◽  
Heat Conduction Equation ◽  
Constitutive Law ◽  
Conduction Equation ◽  
Diffusion Regime ◽  
One Dimensional ◽  
Different Types ◽  
Propagation Regime ◽  
The One

The heat conduction equation with a fractional Jeffreys-type constitutive law is studied. Depending on the value of a characteristic parameter, two fundamentally different types of behavior are established: diffusion regime and propagation regime. In the first case, the considered equation is a generalized diffusion equation, while in the second it is a generalized wave equation. The corresponding memory kernels are expressed in both cases in terms of Mittag–Leffler functions. Explicit representations for the one-dimensional fundamental solution and the mean squared displacement are provided and analyzed analytically and numerically. The one-dimensional fundamental solution is shown to be a spatial probability density function evolving in time, which is unimodal in the diffusion regime and bimodal in the propagation regime. The multi-dimensional fundamental solutions are probability densities only in the diffusion case, while in the propagation case they can have negative values. In addition, two different types of subordination principles are formulated for the two regimes. The Bernstein functions technique is extensively employed in the theoretical proofs.

scholarly journals LONG-TERM MORPHOLOGICAL EVOLUTION MODEL

2018 ◽  
pp. 64
Author(s):  
Bradley Johnson ◽  
Jesse McNinch
Keyword(s):  
South Carolina ◽  
Morphological Evolution ◽  
Shoreline Change ◽  
One Dimensional ◽  
The Past ◽  
Longshore Transport ◽  
Model Predictions ◽  
Erosion And Accretion ◽  
The One

Nearshore morphology models predicting storm-scale erosion have been in use for the past several decades. These empirical tools typically focus on a single time-scale, which limits the utilization. For example, models developed to predict cross-shore storm erosion are poorly suited for longer-term simulations that include the beach recovery between events and gradients in longshore transport. Herein, the one-dimensional model CSHORE is extended to include shoreline change associated with along- shore variation in transport. A comparison of model predictions with long-term shoreline data from South Carolina demonstrate reasonable agreement with both erosion and accretion.

Optimization of the Axial Porosity Distribution of Porous Inserts in a Liquid-Piston Gas Compressor Using a One-Dimensional Formulation

2013 ◽  
Author(s):  
Chao Zhang ◽  
Terrence W. Simon ◽  
Perry Y. Li
Keyword(s):  
Porous Media ◽  
Piston Compressor ◽  
High Porosity ◽  
Porosity Distribution ◽  
One Dimensional ◽  
Piston Speed ◽  
Work Input ◽  
The One ◽  
Liquid Piston ◽  
D Model

A One-Dimensional (One-D) numerical model to calculate transient temperature distributions in a liquid-piston compressor with porous inserts is presented. The liquid-piston compressor is used for Compressed Air Energy Storage (CAES), and the inserted porous media serve the purpose of reducing temperature rise during compression. The One-D model considers heat transfer by convection in both the fluids (gas and liquid) and convective heat exchange with the solid. The Volume of Fluid (VOF) method is used in the model to deal with the moving liquid-gas interface. Solutions of the One-D model are validated against full CFD solutions of the same problem but within a two-dimensional computation domain, and against another study given in the literature. The model is used to optimize the porosity distribution, in the axial direction, of the porous insert. The objective is to minimize the compression work input for a given piston speed and a given overall pressure compression ratio. The model equations are discretized and solved by a finite difference method. The optimization method is based on sensitivity calculations in an iterative procedure. The sensitivity is the partial derivative of compression work with respect to the porosity value at each optimization node. In each optimization round, the One-D model is solved as many times as there are optimization nodes, and each time the porosity value at a single optimization node is changed by a small amount. From these calculations, the sensitivity of changing the porosity distribution to the total work input (objective) is obtained. Based on this, the porosity distribution is updated in the direction that favors the objective. Then, the optimization procedure marches to the next round and the same calculations are completed iteratively until an optimum solution is reached. The optimization shows that porous media with high porosity should be used in the lower part of the chamber and porous media with low porosity should be used in the upper part of the chamber. An optimal distribution of porosity over the chamber is obtained.

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