scholarly journals An improved reduced-order model for pressure drop across arterial stenoses

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258047
Author(s):  
Konstantinos G. Lyras ◽  
Jack Lee
Keyword(s):  
Pressure Drop ◽  
Reduced Order Model ◽  
Accurate Estimation ◽  
Classification Error ◽  
Fractional Flow ◽  
Order Model ◽  
Reduced Order ◽  
Flow Reserve ◽  
Proposed Model ◽  
New Formulation

Quantification of pressure drop across stenotic arteries is a major element in the functional assessment of occlusive arterial disease. Accurate estimation of the pressure drop with a numerical model allows the calculation of Fractional Flow Reserve (FFR), which is a haemodynamic index employed for guiding coronary revascularisation. Its non-invasive evaluation would contribute to safer and cost-effective diseases management. In this work, we propose a new formulation of a reduced-order model of trans-stenotic pressure drop, based on a consistent theoretical analysis of the Navier-Stokes equation. The new formulation features a novel term that characterises the contribution of turbulence effect to pressure loss. Results from three-dimensional computational fluid dynamics (CFD) showed that the proposed model produces predictions that are significantly more accurate than the existing reduced-order models, for large and small symmetric and eccentric stenoses, covering mild to severe area reductions. FFR calculations based on the proposed model produced zero classification error for three classes comprising positive (≤ 0.75), negative (≥ 0.8) and intermediate (0.75 − 0.8) classes.

scholarly journals Estimating the accuracy of a reduced-order model for the calculation of fractional flow reserve (FFR)

2017 ◽  
Vol 34 (1) ◽  
pp. e2908 ◽  
Author(s):  
Etienne Boileau ◽  
Sanjay Pant ◽  
Carl Roobottom ◽  
Igor Sazonov ◽  
Jingjing Deng ◽  
...  
Keyword(s):  
Fractional Flow Reserve ◽  
Reduced Order Model ◽  
Fractional Flow ◽  
Order Model ◽  
Reduced Order ◽  
Flow Reserve

Flows in annuli with longitudinal grooves

2013 ◽  
Vol 716 ◽  
pp. 280-315 ◽  
Author(s):  
H. V. Moradi ◽  
J. M. Floryan
Keyword(s):  
Pressure Drop ◽  
Drag Reduction ◽  
Optimization Procedure ◽  
Optimal Shape ◽  
Laminar Flows ◽  
Reduced Order Model ◽  
Order Model ◽  
Reduced Order ◽  
Pressure Losses ◽  
Optimal Geometry

AbstractAnalysis of pressure losses in laminar flows through annuli fitted with longitudinal grooves has been carried out. The additional pressure gradient required in order to maintain the same flow rate in the grooved annuli, as well as in the reference smooth annuli, is used as a measure of the loss. The groove-induced changes can be represented as a superposition of a pressure drop due to a change in the average position of the bounding cylinders and a pressure drop due to flow modulations induced by the shape of the grooves. The former effect can be evaluated analytically while the latter requires explicit computations. It has been demonstrated that a reduced-order model is an effective tool for extraction of the features of groove geometry that lead to flow modulations relevant to drag generation. One Fourier mode from the Fourier expansion representing the annulus geometry is sufficient to predict pressure losses with an accuracy sufficient for most applications in the case of equal-depth grooves. It is shown that the presence of the grooves may lead to a reduction of pressure loss in spite of an increase of the surface wetted area. The drag-decreasing grooves are characterized by the groove wavenumber $M/ {R}_{1} $ being smaller than a certain critical value, where $M$ denotes the number of grooves and ${R}_{1} $ stands for the radius of the annulus. This number marginally depends on the groove amplitude and does not depend on the flow Reynolds number. It is shown that the drag reduction mechanism relies on the re-arrangement of the bulk flow that leads to the largest mass flow taking place in the area of the largest annulus opening. The form of the optimal grooves from the point of view of the maximum drag reduction has been determined. This form depends on the type of constraints imposed. In general, the optimal shape can be described using the reduced-order model involving only a few Fourier modes. It is shown that in the case of equal-depth grooves, the optimal shape can be approximated using a special form of trapezoid. In the case of unequal-depth grooves, where the groove depth needs to be determined as part of the optimization procedure, the optimal geometry, consisting of the optimal depth and the corresponding optimal shape, can be approximated using a delta function. The maximum possible drag reduction, corresponding to the optimal geometry, has been determined.

A Reduced-Order Model of a Microfluidic Transistor

2013 ◽  
Author(s):  
Joseph Bakarji ◽  
Khoudor Keniar ◽  
Mohammad Cheikh ◽  
Issam Lakkis
Keyword(s):  
Reduced Order Model ◽  
Elastic Model ◽  
Small Signal ◽  
Micro Channel ◽  
Order Model ◽  
Reduced Order ◽  
Proposed Model ◽  
Structure Problem ◽  
Flow Inertia ◽  
The Impact

A reduced-order model of a Microfluidic Transistor is presented. The transistor is essentially a long micro channel between substrate and a membrane that is pressure actuated. The proposed model captures steady (DC) and small signal (AC) behavior of the device in a manner analogous to standard semiconductor transistor models. The model is based on steady and perturbed unsteady solutions of the conservation of mass and momentum, coupled with an elastic model for the membrane. To improve the accuracy and to enhance the range of validity, the model is enhanced by numerical simulations of the coupled fluid-structure problem. The model predicts dependence of the transconductance on the pressure differentials across the membrane and along the channel. The proposed model also investigates the impact of flow inertia, among other effects, on the dynamic behavior of the transistor.

scholarly journals An efficient multigrid-DEIM semi-reduced-order model for simulation of single-phase compressible flow in porous media

2020 ◽  
Author(s):  
Jing-Fa Li ◽  
Bo Yu ◽  
Dao-Bing Wang ◽  
Shu-Yu Sun ◽  
Dong-Liang Sun
Keyword(s):  
Porous Media ◽  
Equation Of State ◽  
Single Phase ◽  
Reduced Order Model ◽  
Flow In Porous Media ◽  
Order Model ◽  
Reduced Order ◽  
Proposed Model ◽  
Speed Up ◽  
Robinson Equation

Abstract In this paper, an efficient multigrid-DEIM semi-reduced-order model is developed to accelerate the simulation of unsteady single-phase compressible flow in porous media. The cornerstone of the proposed model is that the full approximate storage multigrid method is used to accelerate the solution of flow equation in original full-order space, and the discrete empirical interpolation method (DEIM) is applied to speed up the solution of Peng–Robinson equation of state in reduced-order subspace. The multigrid-DEIM semi-reduced-order model combines the computation both in full-order space and in reduced-order subspace, which not only preserves good prediction accuracy of full-order model, but also gains dramatic computational acceleration by multigrid and DEIM. Numerical performances including accuracy and acceleration of the proposed model are carefully evaluated by comparing with that of the standard semi-implicit method. In addition, the selection of interpolation points for constructing the low-dimensional subspace for solving the Peng–Robinson equation of state is demonstrated and carried out in detail. Comparison results indicate that the multigrid-DEIM semi-reduced-order model can speed up the simulation substantially at the same time preserve good computational accuracy with negligible errors. The general acceleration is up to 50–60 times faster than that of standard semi-implicit method in two-dimensional simulations, but the average relative errors of numerical results between these two methods only have the order of magnitude 10−4–10−6%.

Sign in / Sign up

Export Citation Format

Share Document