Review of the Development of Haemodynamic Modelling Techniques to Capture Flow Behaviour in Arteries Affected by Aneurysm, Atherosclerosis and Stenting

2021 ◽  
Author(s):  
Petra N. Williamson ◽  
Paul D. Docherty ◽  
Sina G. Yazdi ◽  
Adib Khanafer ◽  
Natalia Kabaliuk ◽  
...  
Keyword(s):  
Particle Image ◽  
Stent Grafts ◽  
Modelling Method ◽  
Image Velocimetry ◽  
Haemodynamic Changes ◽  
Modelling Techniques ◽  
Computational Fluid Dynamics Cfd ◽  
Aneurysm Dissection ◽  
Developed World ◽  
Insight Into

Abstract Cardiovascular diseases (CVDs) are the leading cause of death in the developed world. CVD can include atherosclerosis, aneurysm, dissection or occlusion of the main arteries. Many CVDs are caused by unhealthy haemodynamics. Some CVDs can be treated with the implantation of stents and stent grafts. Many investigations have sought to understand the effects stents and stent grafts have on arteries and the haemodynamic changes post-treatment. Many studies on stent haemodynamics have been carried out using Computational Fluid Dynamics (CFD), and have yielded significant insight into the effect of stent mesh design on near wall blood flow and improving haemodynamics. Particle Image Velocimetry (PIV) has also been used to capture behaviour of fluids that mimic physiological haemodynamics. However, PIV studies have largely been restricted to unstented models or intra-aneurysmal flow rather than peri or distal stent flow behaviours. PIV has been used both as a standalone measurement method and as a comparison to validate the CFD studies. This article reviews the successes and limitations of several experimental methods used to investigate the haemodynamic effects of stents. The review includes an overview of physiology and relevant mechanics of arteries as well as consideration of boundary conditions and the working fluids used to simulate blood for each modelling method along with the benefits and limitations introduced.

Experimental and Numerical Flow Visualization in Patient Specific Pre Operative Human Airway Geometry

2011 ◽  
Author(s):  
Mathias Vermeulen ◽  
Cedric Van Holsbeke ◽  
Tom Claessens ◽  
Jan De Backer ◽  
Peter Van Ransbeeck ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Particle Image ◽  
Patient Specific ◽  
Lung Volume Reduction ◽  
Cfd Simulations ◽  
Piv Measurements ◽  
Image Velocimetry ◽  
Specific Geometry ◽  
Computational Fluid Dynamics Cfd ◽  
Human Airways

An experimental and numerical platform was developed to investigate the fluidodynamics in human airways. A pre operative patient specific geometry was used to create an identical experimental and numerical model. The experimental results obtained from Particle Image Velocimetry (PIV) measurements were compared to Computational Fluid Dynamics (CFD) simulations under stationary and pulsatile flow regimes. Together these results constitute the first step in predicting the clinical outcome of patients after lung surgeries such as Lung Volume Reduction.

Cinema PIV and Its Application to Impinging Vortex Systems

1999 ◽  
Vol 121 (4) ◽  
pp. 720-724 ◽  
Author(s):  
J.-C. Lin ◽  
D. Rockwell
Keyword(s):  
Particle Image ◽  
Turbulent Shear ◽  
Turbulent Shear Layer ◽  
Image Velocimetry ◽  
Framing Rate ◽  
Image Density ◽  
First Time ◽  
Vortex Systems ◽  
Insight Into ◽  
Pressure Measurement System

An integrated cinema PIV-pressure measurement system allows detailed insight into impinging vortex systems. It employs a high framing rate camera in conjunction with a scanning-laser version of high-image-density particle image velocimetry, thereby generating space-time representations of the flow. Simultaneously, instantaneous surface pressures are acquired. This approach allows the instantaneous velocity and vorticity fields to be related to the induced loading. The instantaneous structure of vortex systems arising from an initially turbulent jet impinging upon an edge and an initially turbulent shear layer past a cavity are quantitatively characterized for the first time. In addition, distinctive mechanisms of vortex-wedge and vortex-corner interactions are related to the occurrence of peak values of instantaneous surface pressure.

The importance of hydrodynamics in UV advanced oxidation reactors

2007 ◽  
Vol 55 (12) ◽  
pp. 53-58 ◽  
Author(s):  
A. Sozzi ◽  
F. Taghipour
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Particle Image Velocimetry ◽  
Particle Image ◽  
Flow Distribution ◽  
Fluence Rate ◽  
Reactor Performance ◽  
Image Velocimetry ◽  
Reactor Axis ◽  
Computational Fluid Dynamics Cfd

The flow field of UV reactors was characterised experimentally using particle image velocimetry (PIV) and modelled with computational fluid dynamics (CFD). The reactor flow was integrated with the radiation fluence rate and photolysis kinetics to calculate the overall conversion of photo-reactant components in annular UV reactors with an inlet parallel and perpendicular to the reactor axis. The results indicated that the fluid flow distribution within the reactor volume affects photo-reactor performance.

scholarly journals Experimental and Numerical Study of Blood Flow in μ-vessels: Influence of the Fahraeus–Lindqvist Effect

Fluids ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 143
Author(s):  
Yorgos G. Stergiou ◽  
Aggelos T. Keramydas ◽  
Antonios D. Anastasiou ◽  
Aikaterini A. Mouza ◽  
Spiros V. Paras
Keyword(s):  
Blood Flow ◽  
Axial Velocity ◽  
Particle Image ◽  
Numerical Study ◽  
Implantable Devices ◽  
Cfd Simulations ◽  
Micro Particle Image Velocimetry ◽  
Image Velocimetry ◽  
Computational Fluid Dynamics Cfd ◽  
Cell Free Layer

The study of hemodynamics is particularly important in medicine and biomedical engineering as it is crucial for the design of new implantable devices and for understanding the mechanism of various diseases related to blood flow. In this study, we experimentally identify the cell free layer (CFL) width, which is the result of the Fahraeus–Lindqvist effect, as well as the axial velocity distribution of blood flow in microvessels. The CFL extent was determined using microscopic photography, while the blood velocity was measured by micro-particle image velocimetry (μ-PIV). Based on the experimental results, we formulated a correlation for the prediction of the CFL width in small caliber (D < 300 μm) vessels as a function of a modified Reynolds number (Re∞) and the hematocrit (Hct). This correlation along with the lateral distribution of blood viscosity were used as input to a “two-regions” computational model. The reliability of the code was checked by comparing the experimentally obtained axial velocity profiles with those calculated by the computational fluid dynamics (CFD) simulations. We propose a methodology for calculating the friction loses during blood flow in μ-vessels, where the Fahraeus–Lindqvist effect plays a prominent role, and show that the pressure drop may be overestimated by 80% to 150% if the CFL is neglected.

Experimental and Numerical Study of the Flow Around a Semi-Submerged Rectangular Cylinder

2012 ◽  
Author(s):  
Tufan Arslan ◽  
Stefano Malavasi ◽  
Bjørnar Pettersen ◽  
Helge I. Andersson
Keyword(s):  
Particle Image ◽  
Model Simulation ◽  
Numerical Study ◽  
Three Dimensional ◽  
Separated Flow ◽  
Piv Measurements ◽  
Rectangular Cylinder ◽  
Image Velocimetry ◽  
Computational Fluid Dynamics Cfd

The present work is motivated by phenomena occurring in the flow field around structures partly submerged in water. A three dimensional unsteady flow around a rectangular cylinder is studied for four different submergence ratios by using computational fluid dynamics (CFD) tools with LES turbulence model. Simulation results are compared to particle image velocimetry (PIV) measurements at Reynolds number Re = 12100 and Froude number Fr = 0.26. Focus in our investigation is on the characterization of the behaviour of vortex structures generated by separated flow. Another target in the study is to obtain better knowledge of the hydrodynamic forces acting on a semi-submerged structure. Computed force coefficients are compared with experimental measurements.

scholarly journals Deep velocimetry: Extracting full velocity distributions from projected images of flowing media

2021 ◽  
Vol 62 (5) ◽  
Author(s):  
James Lindsay Baker ◽  
Itai Einav
Keyword(s):  
Particle Image ◽  
Correlation Method ◽  
Image Correlation ◽  
Analysis Method ◽  
X Ray ◽  
Optical Images ◽  
Image Velocimetry ◽  
Out Of Plane ◽  
Velocity Information ◽  
Insight Into

Abstract Particle image velocimetry (PIV) is a powerful image correlation method for measuring bulk velocity fields of flowing media. It typically uses optical images, representing quasi-two-dimensional experimental slices, to measure a single velocity value at each in-plane position. However, projection-based imaging methods, such as x-ray radiography or shadowgraph imaging, encode additional out-of-plane information that regular PIV is unable to capture. Here, we introduce a new image analysis method, named deep velocimetry, that goes beyond established PIV methods and is capable of extracting full velocity distributions from projected images. The method involves solving a deconvolution inverse problem to recover the distribution at each in-plane position, and is validated using artificial data as well as controlled laboratory x-ray experiments. The additional velocity information delivered by deep velocimetry could provide new insight into a range of fluid and granular flows where out-of-plane variation is significant. Graphic abstract

scholarly journals Experimental Study on the Influence of Bulbous Bow Form on the Velocity Field around the Bow of a Trimaran Using Towed Underwater 2D-3C SPIV

2021 ◽  
Vol 9 (8) ◽  
pp. 905
Author(s):  
Rui Deng ◽  
Shigang Wang ◽  
Wanzhen Luo ◽  
Tiecheng Wu
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Field ◽  
Axial Velocity ◽  
Particle Image ◽  
Stereoscopic Particle Image Velocimetry ◽  
Testing Model ◽  
Image Velocimetry ◽  
Measured Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Bulbous Bow

In this study, particle image velocimetry was applied to measure the flow field around the bow region of a trimaran with different appendages. The dimensionless axial velocity u/U in test planes 1 and 2 of the testing model was measured by using a towed underwater stereoscopic particle image velocimetry (SPIV) system. Based on the measured flow field data, the local sinkage values in test planes 1 and 2 of the testing model with different appendages at speeds of 1.766 and 2.943 m/s were presented. In addition, the effects of speed, bulbous bow type, T foils, and bow wave on the axial velocity u/U were studied in detail. The acquired experimental data help in understanding the distribution of the flow field around the ship bow, and the data can also act as a reference to verify computational fluid dynamics (CFD) results.

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