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Advances in Hemodynamics and Related Biological Flows

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A special issue of Fluids (ISSN 2311-5521).

Deadline for manuscript submissions: 30 July 2024 | Viewed by 5817

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Special Issue Editors

Dr. Mesude Avci

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Guest Editor

Department of Chemical Engineering, Cumhuriyet University, Sivas 58140, Turkey
Interests: CFD simulations; artificial organs; ventricular assist devices

Prof. Dr. Dimitrios V. Papavassiliou

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Guest Editor

School of Chemical, Biological, and Materials Engineering, The University of Oklahoma, Norman, OK 73019, USA
Interests: hemodynamics; nanofluidics; computational transport; turbulent transport; flow and transport in porous media
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The heart and broad-branched vessel system contain blood, and it is their main objective to transport material to and from tissue, prevent fluid loss, and defend the body, constituting the circulatory system. Investigating and understanding the dynamics of blood flow (hemodynamics) and the fluid flow phenomena that are important in related biological flows will improve the design and performance of cardiovascular prosthetic devices and the treatment of cardiovascular disease.

This Special Issue will focus on the latest advances in understanding the physics of blood flow through analytical, experimental, and computational studies of hemodynamics. Recent advances in hemolysis, in cell-level and in molecular-level treatments of hemodynamics, and in computations of fluid–structure interactions are welcome. Both fundamental and applied research, e.g., the design of medical devices, in which hemodynamics is critical to the design process, can be included in manuscripts. Moreover, manuscripts focusing on other biological flow dynamics are welcome.

Dr. Mesude Avci
Prof. Dr. Dimitrios V. Papavassiliou
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Fluids is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

biological flow
hemodynamics
analytical
computational
experimental
blood
fluid dynamics

Published Papers (5 papers)

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Research

17 pages, 6015 KiB

Open AccessArticle

Adjoint Solver-Based Analysis of Mouth–Tongue Morphologies on Vapor Deposition in the Upper Airway

by Mohamed Talaat, Xiuhua Si and Jinxiang Xi

Fluids 2024, 9(5), 104; https://doi.org/10.3390/fluids9050104 - 27 Apr 2024

Viewed by 383

Abstract

Even though inhalation dosimetry is determined by three factors (i.e., breathing, aerosols, and the respiratory tract), the first two categories have been more widely studied than the last. Both breathing and aerosols are quantitative variables that can be easily changed, while respiratory airway morphologies are difficult to reconstruct, modify, and quantify. Although several methods are available for model reconstruction and modification, developing an anatomically accurate airway model and morphing it to various physiological conditions remains labor-intensive and technically challenging. The objective of this study is to explore the feasibility of using an adjoint–CFD model to understand airway shape effects on vapor deposition and control vapor flux into the lung. A mouth–throat model was used, with the shape of the mouth and tongue being automatically varied via adjoint morphing and the vapor transport being simulated using ANSYS Fluent coupled with a wall absorption model. Two chemicals with varying adsorption rates, Acetaldehyde and Benzene, were considered, which exhibited large differences in dosimetry sensitivity to airway shapes. For both chemicals, the maximal possible morphing was first identified and then morphology parametric studies were conducted. Results show that changing the mouth–tongue shape can alter the oral filtration by 3.2% for Acetaldehyde and 0.27% for Benzene under a given inhalation condition. The front tongue exerts a significant impact on all cases considered, while the impact of other regions varies among cases. This study demonstrates that the hybrid adjoint–CFD approach can be a practical and efficient method to investigate morphology-associated variability in the dosimetry of vapors and nanomedicines under steady inhalation. Full article

(This article belongs to the Special Issue Advances in Hemodynamics and Related Biological Flows)

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18 pages, 6388 KiB

Open AccessArticle

Computational Analysis of Blood Flow in Healthy Pulmonary Arteries in Comparison to Repaired Tetralogy of Fallot Results: A Small Cohort Study

by Maria Boumpouli, Scott MacDonald Black and Asimina Kazakidi

Fluids 2024, 9(4), 85; https://doi.org/10.3390/fluids9040085 - 01 Apr 2024

Viewed by 651

Abstract

Characterization of the physiological hemodynamic environment in normal pulmonary arteries is a key factor in understanding pathological conditions. This study aimed to analyze the morphology and hemodynamics in the healthy adult pulmonary bifurcation in comparison to age-matched repaired Tetralogy of Fallot (rTOF) geometries. The pulmonary trunk of five healthy volunteers was reconstructed from 4D Flow-MRI data and was compared to rTOF results. Subject-specific boundary conditions were assigned in both the inlet and outlets of the models, and flow characteristics were analyzed computationally. The morphological and flow features were consistent among the healthy geometries, highlighting the ability of an averaged geometry derived from this small cohort to capture the main flow characteristics. A slightly higher mean time-averaged wall shear stress (TAWSS) was found in the right pulmonary artery, which was also the branch with a higher mean curvature and local Reynolds number. Compared to rTOF results, the averaged healthy geometry demonstrated more than an 8-fold lower value in TAWSS, with the individual patient-specific healthy volunteers showing further reduced TAWSS than the rTOF patients. These observations could be useful in clinical assessment and decision making based on hemodynamic indices. Full article

(This article belongs to the Special Issue Advances in Hemodynamics and Related Biological Flows)

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15 pages, 2417 KiB

Open AccessArticle

Computational Flow Diverter Implantation—A Comparative Study on Pre-Interventional Simulation and Post-Interventional Device Positioning for a Novel Blood Flow Modulator

by Maximilian Thormann, Janneck Stahl, Laurel Marsh, Sylvia Saalfeld, Nele Sillis, Andreas Ding, Anastasios Mpotsaris, Philipp Berg and Daniel Behme

Fluids 2024, 9(3), 55; https://doi.org/10.3390/fluids9030055 - 23 Feb 2024

Viewed by 1351

Abstract

Due to their effect on aneurysm hemodynamics, flow diverters (FD) have become a routine endovascular therapy for intracranial aneurysms. Since over- and undersizing affect the device’s hemodynamic abilities, selecting the correct device diameter and accurately simulating FD placement can improve patient-specific outcomes. The purpose of this study was to validate the accuracy of virtual flow diverter deployments in the novel Derivo^® 2 device. We retrospectively analyzed blood flows in ten FD placements for which 3D DSA datasets were available pre- and post-intervention. All patients were treated with a second-generation FD Derivo^® 2 (Acandis GmbH, Pforzheim, Germany) and post-interventional datasets were compared to virtual FD deployment at the implanted position for implanted stent length, stent diameters, and curvature analysis using ANKYRAS (Galgo Medical, Barcelona, Spain). Image-based blood flow simulations of pre- and post-interventional configurations were conducted. The mean length of implanted FD was 32.61 (±11.18 mm). Overall, ANKYRAS prediction was good with an average deviation of 8.4% (±5.8%) with a mean absolute difference in stent length of 3.13 mm. There was a difference of 0.24 mm in stent diameter amplitude toward ANKYRAS simulation. In vessels exhibiting a high degree of curvature, however, relevant differences between simulated and real-patient data were observed. The intrasaccular blood flow activity represented by the wall shear stress was qualitatively reduced in all cases. Inflow velocity decreased and the pulsatility over the cardiac cycle was weakened. Virtual stenting is an accurate tool for FD positioning, which may help facilitate flow FDs’ individualization and assess their hemodynamic impact. Challenges posed by complex vessel anatomy and high curvatures must be addressed. Full article

(This article belongs to the Special Issue Advances in Hemodynamics and Related Biological Flows)

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21 pages, 5865 KiB

Open AccessArticle

Hemodynamic Insights into Abdominal Aortic Aneurysms: Bridging the Knowledge Gap for Improved Patient Care

by Suvash C. Saha, Isabella Francis, Goutam Saha, Xinlei Huang and Md. Mamun Molla

Fluids 2024, 9(2), 50; https://doi.org/10.3390/fluids9020050 - 15 Feb 2024

Cited by 1 | Viewed by 1361

Abstract

Background: Abdominal aortic aneurysms (AAAs) present a formidable public health concern due to their propensity for localized, anomalous expansion of the abdominal aorta. These insidious dilations, often in their early stages, mask the life-threatening potential for rupture, which carries a grave prognosis. Understanding the hemodynamic intricacies governing AAAs is paramount for predicting aneurysmal growth and the imminent risk of rupture. Objective: Our extensive investigation delves into this complex hemodynamic environment intrinsic to AAAs, utilizing comprehensive numerical analyses of the physiological pulsatile blood flow and realistic boundary conditions to explore the multifaceted dynamics influencing aneurysm rupture risk. Our study introduces novel elements by integrating these parameters into the overall context of aneurysm pathophysiology, thus advancing our understanding of the intricate mechanics governing their evolution and rupture. Methods: Conservation of mass and momentum equations are used to model the blood flow in an AAAs, and these equations are solved using a finite volume-based ANSYS Fluent solver. Resistance pressure outlets following a three-element Windkessel model were imposed at each outlet to accurately model the blood flow and the AAAs’ shear stress. Results: Our results uncover elevated blood flow velocities within an aneurysm, suggesting an augmented risk of future rupture due to increased stress in the aneurysm wall. During the systole phase, high wall shear stress (WSS) was observed, typically associated with a lower risk of rupture, while a low oscillatory shear index (OSI) was noted, correlating with a decreased risk of aneurysm expansion. Conversely, during the diastole phase, low WSS and a high OSI were identified, potentially weakening the aneurysm wall, thereby promoting expansion and rupture. Conclusion: Our study underscores the indispensable role of computational fluid dynamic (CFD) techniques in the diagnostic, therapeutic, and monitoring realms of AAAs. This body of research significantly advances our understanding of aneurysm pathophysiology, thus offering pivotal insights into the intricate mechanics underpinning their progression and rupture, informing clinical interventions and enhancing patient care. Full article

(This article belongs to the Special Issue Advances in Hemodynamics and Related Biological Flows)

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10 pages, 3814 KiB

Open AccessArticle

A Computational Fluid Dynamics Study to Compare Two Types of Arterial Cannulae for Cardiopulmonary Bypass

by Vera Gramigna, Arrigo Palumbo, Michele Rossi and Gionata Fragomeni

Fluids 2023, 8(11), 302; https://doi.org/10.3390/fluids8110302 - 16 Nov 2023

Viewed by 1489

Abstract

Thanks to recent technological and IT advances, there have been rapid developments in biomedical and health research applications of computational fluid dynamics. This is a methodology of computer-based simulation that uses numerical solutions of the governing equations to simulate real fluid flows. The aim of this study is to investigate, using a patient-specific computational fluid dynamics analysis, the hemodynamic behavior of two arterial cannulae, with two different geometries, used in clinical practice during cardiopulmonary bypass. A realistic 3D model of the aorta is extracted from a subject’s CT images using segmentation and reverse engineering techniques. The two cannulae, with similar geometry except for the distal end (straight or curved tip), are modeled and inserted at the specific position in the ascending aorta. The assumption of equal boundary conditions is adopted for the two simulations in order to analyze only the effects of a cannula’s geometry on hemodynamic behavior. Simulation results showed a greater percentage of the total output directed towards the supra-aortic vessels with the curved tip cannula (66% vs. 54%), demonstrating that the different cannula tips geometry produces specific advantages during cardiopulmonary bypass. Indeed, the straight one seems to generate a steadier flow pattern with good recirculation in the ascending aorta. Full article

(This article belongs to the Special Issue Advances in Hemodynamics and Related Biological Flows)

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