Biological Fluid Dynamics

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

Deadline for manuscript submissions: closed (30 September 2023) | Viewed by 11265

Special Issue Editors

School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK
Interests: biofluids; upper airways; airborne infection; air disinfection; UVC disinfection; blood circulatory support systems; urinary system
Special Issues, Collections and Topics in MDPI journals
College of Water Conservancy & Hydropower Engineering, Hohai University, Nanjing 210098, China
Interests: blood flow; red blood cells; stenosed vessels; rheology; hemorheology; microcirculation; computational fluid dynamics
Special Issues, Collections and Topics in MDPI journals
Department of Mechanical Engineering and Materials Science and Engineering, Cyprus University of Technology, Limassol 3036, Cyprus
Interests: biofluid mechanics; red blood cells; blood flow; bifurcation; microfluidics; modeling; experiments
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Biofluid dynamics is a wide topic that merges mechanical and biological engineering as well as several fields of science. It involves a range of issues from external to internal flows and from how birds fly and animals swim to internal blood and urinary flows. The complexities of such flows in terms of geometry, multi-scale effects, fluid–structure interaction, and, in many cases, non-Newtonian fluid properties (such as in small blood veins) impose significant challenges when it comes to studying these flows and, furthermore, to the design of devices aimed at controlling such flows. The recent COVID-19 pandemic has shown the complexity of analyzing bio-fluid phenomena involving both external and internal flows, multi-scale effects, and the strong effect of human behavior, which is sometimes difficult to predict.

For this Special Issue, we call for a wide range of papers, including those covering analytical, computational, and experimental studies of biofluids as they are related to humans and animals. Manuscripts can focus on fundamental research or applied research, e.g., the design of biofluid devices. Of particular interest are manuscripts looking at the blood, renal, and respiratory systems as well as at the external flows of swimmers, flying animals, and pathogens spreading through air/gas and water/liquid. Nonetheless, manuscripts dealing with any other field related to biofluid dynamics are welcome as well.

Dr. Eldad Avital
Dr. Dong Xu
Dr. Efstathios Kaliviotis
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

  • bio-fluids
  • analytical, computational, and experimental
  • blood
  • renal
  • respiratory
  • swimmers
  • flying animals
  • pathogens and fluid dynamics

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Published Papers (7 papers)

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Research

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22 pages, 15326 KiB  
Article
A Comparison of Newtonian and Non-Newtonian Models for Simulating Stenosis Development at the Bifurcation of the Carotid Artery
by Aikaterini C. Stamou, Jovana Radulovic and James M. Buick
Fluids 2023, 8(10), 282; https://doi.org/10.3390/fluids8100282 - 20 Oct 2023
Viewed by 1358
Abstract
Blood is a shear-thinning non-Newtonian fluid in which the viscosity reduces with the shear rate. When simulating arterial flow, it is well established that the non-Newtonian nature is important in the smallest vessels; however, there is no consistent view as to whether it [...] Read more.
Blood is a shear-thinning non-Newtonian fluid in which the viscosity reduces with the shear rate. When simulating arterial flow, it is well established that the non-Newtonian nature is important in the smallest vessels; however, there is no consistent view as to whether it is required in larger arteries, such as the carotid. Here, we investigate the importance of incorporating a non-Newtonian model when applying a plaque deposition model which is based on near-wall local haemodynamic markers: the time-averaged near wall velocity and the ratio of the oscillatory shear index to the wall shear stress. In both cases the plaque deposition was similar between the Newtonian and non-Newtonian simulations, with the observed differences being no more significant than the differences between the selected markers. More significant differences were observed in the haemodynamic properties in the stenosed region, the most significant being that lower levels of near-wall reverse flow were observed for a non-Newtonian fluid. Full article
(This article belongs to the Special Issue Biological Fluid Dynamics)
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20 pages, 7441 KiB  
Article
Highlighting Hemodynamic Risks for Bioresorbable Stents in Coronary Arteries
by Marcus S. Elliott, Jonathan S. Cole, Ross W. Blair and Gary H. Menary
Fluids 2023, 8(9), 241; https://doi.org/10.3390/fluids8090241 - 25 Aug 2023
Viewed by 854
Abstract
A three-dimensional, transient computational fluid dynamics analysis was conducted on an idealised geometry of a coronary artery fitted with representative geometries of an Absorb bioresorbable vascular scaffold (BVS) or a Xience drug-eluting stent (DES) in order to identify and compare areas of disturbed [...] Read more.
A three-dimensional, transient computational fluid dynamics analysis was conducted on an idealised geometry of a coronary artery fitted with representative geometries of an Absorb bioresorbable vascular scaffold (BVS) or a Xience drug-eluting stent (DES) in order to identify and compare areas of disturbed flow and potential risk sites. A non-Newtonian viscosity model was used with a transient velocity boundary condition programmed with user-defined functions. At-risk areas were quantified in terms of several parameters linked to restenosis: wall shear stress, time-averaged wall shear stress, oscillatory shear index, particle residence time, and shear rate. Results indicated that 71% of the BVS stented surface area had time-averaged wall shear stress values under 0.4 Pa compared to 45% of the DES area. Additionally, high particle residence times were present in 23% and 8% of the BVS and DES areas, respectively, with risk areas identified as being more prominent in close proximity to crowns and link struts. These results suggest an increased risk for thrombosis and neointimal hyperplasia for the BVS compared to the DES, which is in agreement with the outcomes of clinical trials. It is intended that the results of this study may be used as a pre-clinical tool to aid in the design of bioresorbable coronary stents. Full article
(This article belongs to the Special Issue Biological Fluid Dynamics)
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14 pages, 6914 KiB  
Article
Experimental Study on the Effect of the Angle of Attack on the Flow-Induced Vibration of a Harbor Seal’s Whisker
by Yuhan Wei, Chunning Ji, Dekui Yuan, Liqun Song and Dong Xu
Fluids 2023, 8(7), 206; https://doi.org/10.3390/fluids8070206 - 14 Jul 2023
Viewed by 1185
Abstract
A harbor seal’s whisker is able to sense the trailing vortices of marine organisms due to its unique three-dimensional wavy shape, which suppresses the vibrations caused by its own vortex-shedding, while exciting large-amplitude and synchronized vibrations in a wake flow. This provides insight [...] Read more.
A harbor seal’s whisker is able to sense the trailing vortices of marine organisms due to its unique three-dimensional wavy shape, which suppresses the vibrations caused by its own vortex-shedding, while exciting large-amplitude and synchronized vibrations in a wake flow. This provides insight into the development of whisker-inspired sensors, which have broad applications in the fields of ocean exploration and marine surveys. However, the harbor seal’s whisker may lose its vibration suppression ability when the angle of attack (AoA) of the incoming flow is large. In order to explore the flow-induced vibration (FIV) features of a harbor seal’s whisker at various angles of attack (θ=090), this study experimentally investigates the effect of AoA on the vibration response of a whisker model in a wide range of reduced velocities (Ur = 3–32.2) and the Reynolds number, Re = 400–7000, in a circulating water flume. Meanwhile, for the sake of comparison, the FIV response of an elliptical cylinder with the same equivalent diameters is also presented. The results indicate that an increase in AoA enhances the vibration amplitude and expands the lock-in range for both the whisker model and the elliptical cylinder. The whisker model effectively suppresses vibration responses at θ=0 due to its unique three-dimensional wavy shape. However, when θ30, the wavy surface structure gradually loses its suppression ability, resulting in large-amplitude vibration responses similar to those of the elliptical cylinder. For θ = 30 and 45, the vibration responses of the whisker model and the elliptical cylinder undergo three vibration regimes, i.e., vortex-induced vibration, transition response, and turbulent-induced vibration, with the increasing Ur. However, at θ = 60 and 90, the vortex-shedding gradually controls the FIV response, and only the vortex-induced vibration is observed. Full article
(This article belongs to the Special Issue Biological Fluid Dynamics)
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14 pages, 2772 KiB  
Article
Suitability of Different Blood-Analogous Fluids in Determining the Pump Characteristics of a Ventricular Assist Device
by Finn Knüppel, Inga Thomas, Frank-Hendrik Wurm and Benjamin Torner
Fluids 2023, 8(5), 151; https://doi.org/10.3390/fluids8050151 - 11 May 2023
Cited by 1 | Viewed by 1655
Abstract
Ventricular assist devices (VADs) are implantable turbomachines that save and improve the lives of patients with severe heart failure. In the preclinical evaluation, a VAD design must be experimentally or numerically tested regarding its pump characteristics, primarily for its pressure buildup (pressure head  [...] Read more.
Ventricular assist devices (VADs) are implantable turbomachines that save and improve the lives of patients with severe heart failure. In the preclinical evaluation, a VAD design must be experimentally or numerically tested regarding its pump characteristics, primarily for its pressure buildup (pressure head H) since it must provide the cardiovascular system with a sufficient blood flow rate Q. Those pump characteristics are determined on a test bench. Here, a glycerol-water mixture is almost exclusively used as blood-analogous fluid, which should reflect the properties (density, viscosity) of blood as close as possible. However, glycerol water has some disadvantages, such as a higher density compared to real blood and a relatively high cost. Therefore, the study aimed to analyze six different blood analogous fluids to select the most suitable one in consideration of fluid handling, costs, and, most importantly, fluid properties (material and rheological). First, all fluids were mixed to achieve reference values of blood density and viscosity from the literature. Afterwards, the pump characteristics (pressure heads and efficiencies via the VAD) were experimentally and numerically determined and compared among each other and with literature values. Of all six investigated fluids, only the aqueous–polyethylene glycol 200 (PEG 200) solution matches exactly the desired blood properties, and the pump characteristics of this fluid are in the expected range for the analyzed operation point of the VAD. Another advantage is that the cost of the mixture is 35% lower compared to glycerol water. Additionally, we demonstrate that non-Newtonian flow behavior has little effect on the pump characteristics in our VAD. Full article
(This article belongs to the Special Issue Biological Fluid Dynamics)
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18 pages, 6967 KiB  
Article
Conceptual Design of a UVC-LED Air Purifier to Reduce Airborne Pathogen Transmission—A Feasibility Study
by Saket Kapse, Dena Rahman, Eldad J. Avital, Nithya Venkatesan, Taylor Smith, Lidia Cantero-Garcia, Fariborz Motallebi, Abdus Samad and Clive B. Beggs
Fluids 2023, 8(4), 111; https://doi.org/10.3390/fluids8040111 - 27 Mar 2023
Cited by 1 | Viewed by 1984
Abstract
Existing indoor closed ultraviolet-C (UVC) air purifiers (UVC in a box) have faced technological challenges during the COVID-19 breakout, owing to demands of low energy consumption, high flow rates, and high kill rates at the same time. A new conceptual design of a [...] Read more.
Existing indoor closed ultraviolet-C (UVC) air purifiers (UVC in a box) have faced technological challenges during the COVID-19 breakout, owing to demands of low energy consumption, high flow rates, and high kill rates at the same time. A new conceptual design of a novel UVC-LED (light-emitting diode) air purifier for a low-cost solution to mitigate airborne diseases is proposed. The concept focuses on performance and robustness. It contains a dust-filter assembly, an innovative UVC chamber, and a fan. The low-cost dust filter aims to suppress dust accumulation in the UVC chamber to ensure durability and is conceptually shown to be easily replaced while mitigating any possible contamination. The chamber includes novel turbulence-generating grids and a novel LED arrangement. The turbulent generator promotes air mixing, while the LEDs inactivate the pathogens at a high flow rate and sufficient kill rate. The conceptual design is portable and can fit into ventilation ducts. Computational fluid dynamics and UVC ray methods were used for analysis. The design produces a kill rate above 97% for COVID and tuberculosis and above 92% for influenza A at a flow rate of 100 L/s and power consumption of less than 300 W. An analysis of the dust-filter performance yields the irradiation and flow fields. Full article
(This article belongs to the Special Issue Biological Fluid Dynamics)
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27 pages, 11157 KiB  
Article
Influence of Morphological Parameters on the Flow Development within Human Airways
by Andres Santiago Espinosa-Moreno, Carlos Alberto Duque-Daza and Diego Alexander Garzón-Alvarado
Fluids 2023, 8(3), 78; https://doi.org/10.3390/fluids8030078 - 21 Feb 2023
Viewed by 1321
Abstract
Anatomical airways parameters, such as length, diameter and angles, have a strong effect on the flow dynamics. Aiming to explore the effect of variations of the bifurcation angle (BA) and carina rounding radius (CRR) of lower human airways on respiratory processes, numerical simulations [...] Read more.
Anatomical airways parameters, such as length, diameter and angles, have a strong effect on the flow dynamics. Aiming to explore the effect of variations of the bifurcation angle (BA) and carina rounding radius (CRR) of lower human airways on respiratory processes, numerical simulations of airflow during inhalation and exhalation were performed using synthetic bifurcation models. Geometries for the airways models were parameterized based on a set of different BA’s and several CRR’s. A range of Reynolds numbers (Re), relevant to the human breathing process, were selected to analyze airflow behavior. The numerical results showed a significant influence of BA and the CRR on the development of the airflow within the airways, and, therefore, affecting the following relevant features of the flow: the deformation of velocity profiles, alterations of pressure drop, flow patterns, and, finally, enhancement or attenuation of wall shear stresses (WSS) appearing during the regular respiratory process. The numerical results showed that increases in the bifurcation angle value were accompanied by pressure increases of about 20%, especially in the regions close to the bifurcation. Similarly, increases in the BA value led to a reduction in peak shear stresses of up to 70%. For the ranges of angles and radii explored, an increase in pressure of about 20% and a reduction in wall shear stress of more than 400% were obtained by increasing the carina rounding radius. Analysis of the coherent structures and secondary flow patterns also revealed a direct relationship between the location of the vortical structures, the local maxima of the velocity profiles and the local vorticity minima. This relationship was observed for all branches analyzed, for both the inhalation and exhalation processes of the respiratory cycle. Full article
(This article belongs to the Special Issue Biological Fluid Dynamics)
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Review

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24 pages, 4808 KiB  
Review
Fluid–Structure Interaction Aortic Valve Surgery Simulation: A Review
by Alex G. Kuchumov, Anastasiya Makashova, Sergey Vladimirov, Vsevolod Borodin and Anna Dokuchaeva
Fluids 2023, 8(11), 295; https://doi.org/10.3390/fluids8110295 - 04 Nov 2023
Cited by 1 | Viewed by 2000
Abstract
The complicated interaction between a fluid flow and a deformable structure is referred to as fluid–structure interaction (FSI). FSI plays a crucial role in the functioning of the aortic valve. Blood exerts stresses on the leaflets as it passes through the opening or [...] Read more.
The complicated interaction between a fluid flow and a deformable structure is referred to as fluid–structure interaction (FSI). FSI plays a crucial role in the functioning of the aortic valve. Blood exerts stresses on the leaflets as it passes through the opening or shutting valve, causing them to distort and vibrate. The pressure, velocity, and turbulence of the fluid flow have an impact on these deformations and vibrations. Designing artificial valves, diagnosing and predicting valve failure, and improving surgical and interventional treatments all require the understanding and modeling of FSI in aortic valve dynamics. The most popular techniques for simulating and analyzing FSI in aortic valves are computational fluid dynamics (CFD) and finite element analysis (FEA). By studying the relationship between fluid flow and valve deformations, researchers and doctors can gain knowledge about the functioning of valves and possible pathological diseases. Overall, FSI is a complicated phenomenon that has a great impact on how well the aortic valve works. Aortic valve diseases and disorders can be better identified, treated, and managed by comprehending and mimicking this relationship. This article provides a literature review that compiles valve reconstruction methods from 1952 to the present, as well as FSI modeling techniques that can help advance valve reconstruction. The Scopus, PubMed, and ScienceDirect databases were used in the literature search and were structured into several categories. By utilizing FSI modeling, surgeons, researchers, and engineers can predict the behavior of the aortic valve before, during, and after surgery. This predictive capability can contribute to improved surgical planning, as it provides valuable insights into hemodynamic parameters such as blood flow patterns, pressure distributions, and stress analysis. Additionally, FSI modeling can aid in the evaluation of different treatment options and surgical techniques, allowing for the assessment of potential complications and the optimization of surgical outcomes. It can also provide valuable information on the long-term durability and functionality of prosthetic valves. In summary, fluid–structure interaction modeling is an effective tool for predicting the outcomes of aortic valve surgery. It can provide valuable insights into hemodynamic parameters and aid in surgical planning, treatment evaluation, and the optimization of surgical outcomes. Full article
(This article belongs to the Special Issue Biological Fluid Dynamics)
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