Special Issue "Computational Biofluid Mechanics"

A special issue of Fluids (ISSN 2311-5521). This special issue belongs to the section "Mathematical and Computational Fluid Mechanics".

Deadline for manuscript submissions: closed (30 June 2021).

Special Issue Editors

Dr. Fang-Bao Tian
E-Mail Website
Guest Editor
School of Engineering and Information Technology, University of New South Wales Canberra, Canberra, ACT 2610, Australia
Interests: theoretical and computational fluid dynamics; computational bio-mechanics; fluid-structure interaction; numerical partial differential equations; immersed-boundary method; Lattice Boltzmann method; finite element methods; Non-Newtonian fluid; applied mathematics
Dr. Li Wang
E-Mail
Assistant Guest Editor
School of Engineering and Information Technology, University of New South Wales, Canberra, ACT 2610, Australia
Interests: computational fluid dynamics; fluid-structure interaction; immersed-boundary method; Lattice Boltzmann method

Special Issue Information

Dear Colleagues,

Computational biofluid mechanics is an emerging area involving complex fluids, complex structures and complex geometries. Modeling of the computational biofluid mechanics and understanding the underlying flow physics are of cruicial importance in uncovering the mystery in this field and its applications in biomimetics, biomedcine and beyond. This Special Issue of Fluids is dedicated to the recent advances in computational biofluid mechanics, including numerical methods and applications in a variety of topics.

Dr. Fang-Bao Tian
Dr. Li Wang
Guest Editors

Manuscript Submission Information

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Keywords

  • aerodynamics of bio-inspired flapping wings
  • hydrodynamics of swimmers
  • numerical methods for biological flows
  • biomimetic fluid dynamics
  • blood and blood cell flows

Published Papers (6 papers)

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Research

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Article
Numerical Study of the Unsteady Flow in Simplified and Realistic Iliac Bifurcation Models
Fluids 2021, 6(8), 284; https://doi.org/10.3390/fluids6080284 - 14 Aug 2021
Cited by 1 | Viewed by 360
Abstract
Cardiovascular diseases are a major cause of death and disability worldwide and they are commonly associated with the occurrence of atherosclerotic plaque deposition in the vessel walls, a process denoted as atherosclerosis. This is a chronic and progressive inflammatory disease of large-/medium-sized blood [...] Read more.
Cardiovascular diseases are a major cause of death and disability worldwide and they are commonly associated with the occurrence of atherosclerotic plaque deposition in the vessel walls, a process denoted as atherosclerosis. This is a chronic and progressive inflammatory disease of large-/medium-sized blood vessels that affects blood flow profiles, with the abdominal aorta and its branches being one of the locations prone to the development of this pathology, due to their curvatures and bifurcations. In this regard, the effect of flow patterns was studied and compared for both a simplified three-dimensional model of aorta bifurcation on the iliac arteries and a realistic model of iliac bifurcation, which was constructed from a computational tomography medical image. The flow patterns were analyzed in terms of velocity and wall shear stress distribution, but a special focus was given to the size and location of the recirculation zone. The simulations were performed using the Computational Fluid Dynamics software, FLUENT, taking into account the cardiac cycle profile at the infrarenal aorta. The shear stress and the velocity distribution observed for both models indicated that higher shear stress occurred along the flow divider wall (inner wall) and low shear stress occurred along the outer walls. In addition, the results demonstrated that the wall shear stress profiles were deeply affected by the transient profile of the cardiac cycle, with the deceleration phase being the most critical phase to the occurrence of backflow. Full article
(This article belongs to the Special Issue Computational Biofluid Mechanics)
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Article
Fluid Flow Characteristics of Healthy and Calcified Aortic Valves Using Three-Dimensional Lagrangian Coherent Structures Analysis
Fluids 2021, 6(6), 203; https://doi.org/10.3390/fluids6060203 - 31 May 2021
Cited by 2 | Viewed by 872
Abstract
Aortic valve calcification is an important cardiovascular disorder that deteriorates the accurate functioning of the valve leaflets. The increasing stiffness due to the calcification prevents the complete closure of the valve and therefore leads to significant hemodynamic alterations. Computational fluid dynamics (CFD) modeling [...] Read more.
Aortic valve calcification is an important cardiovascular disorder that deteriorates the accurate functioning of the valve leaflets. The increasing stiffness due to the calcification prevents the complete closure of the valve and therefore leads to significant hemodynamic alterations. Computational fluid dynamics (CFD) modeling enables the investigation of the entire flow domain by processing medical images from aortic valve patients. In this study, we computationally modeled and simulated a 3D aortic valve using patient-specific dimensions of the aortic root and aortic sinus. Leaflet stiffness is deteriorated in aortic valve disease due to calcification. In order to investigate the influence of leaflet calcification on flow dynamics, three different leaflet-stiffness values were considered for healthy, mildly calcified, and severely calcified leaflets. Time-dependent CFD results were used for applying the Lagrangian coherent structures (LCS) technique by performing finite-time Lyapunov exponent (FTLE) computations along with Lagrangian particle residence time (PRT) analysis to identify unique vortex structures at the front and backside of the leaflets. Obtained results indicated that the peak flow velocity at the valve orifice increased with the calcification rate. For the healthy aortic valve, a low-pressure field was observed at the leaflet tips. This low-pressure field gradually expanded through the entire aortic sinus as the calcification level increased. FTLE field plots of the healthy and calcified valves showed a variety of differences in terms of flow structures. When the number of fluid particles in the healthy valve model was taken as reference, 1.59 and 1.74 times more particles accumulated in the mildly and severely calcified valves, respectively, indicating that the calcified valves were not sufficiently opened to allow normal mass flow rates. Full article
(This article belongs to the Special Issue Computational Biofluid Mechanics)
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Article
Near Stall Unsteady Flow Responses to Morphing Flap Deflections
Fluids 2021, 6(5), 180; https://doi.org/10.3390/fluids6050180 - 07 May 2021
Viewed by 951
Abstract
The unsteady flow characteristics and responses of an NACA 0012 airfoil fitted with a bio-inspired morphing trailing edge flap (TEF) at near-stall angles of attack (AoA) undergoing downward deflections are investigated at a Reynolds number of 0.62 × 106 near stall. An [...] Read more.
The unsteady flow characteristics and responses of an NACA 0012 airfoil fitted with a bio-inspired morphing trailing edge flap (TEF) at near-stall angles of attack (AoA) undergoing downward deflections are investigated at a Reynolds number of 0.62 × 106 near stall. An unsteady geometric parametrization and a dynamic meshing scheme are used to drive the morphing motion. The objective is to determine the susceptibility of near-stall flow to a morphing actuation and the viability of rapid downward flap deflection as a control mechanism, including its effect on transient forces and flow field unsteadiness. The dynamic flow responses to downward deflections are studied for a range of morphing frequencies (at a fixed large amplitude), using a high-fidelity, hybrid RANS-LES model. The time histories of the lift and drag coefficient responses exhibit a proportional relationship between the morphing frequency and the slope of response at which these quantities evolve. Interestingly, an overshoot in the drag coefficient is captured, even in quasi-static conditions, however this is not seen in the lift coefficient. Qualitative analysis confirms that an airfoil in near stall conditions is receptive to morphing TEF deflections, and that some similarities triggering the stall exist between downward morphing TEFs and rapid ramp-up type pitching motions. Full article
(This article belongs to the Special Issue Computational Biofluid Mechanics)
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Article
A Computational Analysis of the Influence of a Pressure Wire in Evaluating Coronary Stenosis
Fluids 2021, 6(4), 165; https://doi.org/10.3390/fluids6040165 - 20 Apr 2021
Cited by 1 | Viewed by 557
Abstract
Cardiovascular disease is one of the world’s leading causes of morbidity and mortality. Fractional flow reserve (FFR) was proposed in the 1990s to more accurately evaluate the functional severity of intermediate coronary stenosis, and it is currently the gold standard in cardiac catheterization [...] Read more.
Cardiovascular disease is one of the world’s leading causes of morbidity and mortality. Fractional flow reserve (FFR) was proposed in the 1990s to more accurately evaluate the functional severity of intermediate coronary stenosis, and it is currently the gold standard in cardiac catheterization laboratories where coronary pressure and flow are routinely obtained. The clinical measurement of FFR relies on a pressure wire for the recording of pressures; however, in computational fluid dynamics studies, an FFR is frequently predicted using a wire-absent model. We aim to investigate the influence of the physical presence of a 0.014-inch (≈0.36 mm) pressure wire in the calculation of virtual FFR. Ideal and patient-specific models were simulated with the absence and presence of a pressure wire. The computed FFR reduced from 0.96 to 0.93 after inserting a wire in a 3-mm non-stenosed (pipe) ideal model. In mild stenotic cases, the difference in FFR between the wire-absent and wire-included models was slight. The overestimation in severe case was large but is of less clinical significance because, in practice, this tight lesion does not require sophisticated measurement to be considered critical. However, an absence of the pressure wire in simulations could contribute to an over-evaluation for an intermediate coronary stenosis. Full article
(This article belongs to the Special Issue Computational Biofluid Mechanics)
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Review

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Review
Numerical Modeling of Sperm Swimming
Fluids 2021, 6(2), 73; https://doi.org/10.3390/fluids6020073 - 07 Feb 2021
Viewed by 1673
Abstract
Due to rising human infertility, sperm motility has been an important subject. Among the hundreds of millions of sperms on the journey up the oviducts, only a few excellent travelers will reach the eggs. This journey is affected by many factors, some of [...] Read more.
Due to rising human infertility, sperm motility has been an important subject. Among the hundreds of millions of sperms on the journey up the oviducts, only a few excellent travelers will reach the eggs. This journey is affected by many factors, some of which include sperm quality, sperm density, fluid rheology and chemotaxis. In addition, the sperm swimming through different body tracks and fluids involves complex sperm flagellar, complex fluid environment, and multi-sperm and sperm-wall interactions. Therefore, this topic has generated substantial research interest. In this paper, we present a review of computational studies on sperm swimming from an engineering perspective with focus on both simplified theoretical methods and fluid–structure interaction methods. Several open issues in this field are highlighted. Full article
(This article belongs to the Special Issue Computational Biofluid Mechanics)
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Review
Blood Flow Modeling in Coronary Arteries: A Review
Fluids 2021, 6(2), 53; https://doi.org/10.3390/fluids6020053 - 23 Jan 2021
Cited by 6 | Viewed by 1193
Abstract
Atherosclerosis is one of the main causes of cardiovascular events, namely, myocardium infarction and cerebral stroke, responsible for a great number of deaths every year worldwide. This pathology is caused by the progressive accumulation of low-density lipoproteins, cholesterol, and other substances on the [...] Read more.
Atherosclerosis is one of the main causes of cardiovascular events, namely, myocardium infarction and cerebral stroke, responsible for a great number of deaths every year worldwide. This pathology is caused by the progressive accumulation of low-density lipoproteins, cholesterol, and other substances on the arterial wall, narrowing its lumen. To date, many hemodynamic studies have been conducted experimentally and/or numerically; however, this disease is not yet fully understood. For this reason, the research of this pathology is still ongoing, mainly, resorting to computational methods. These have been increasingly used in biomedical research of atherosclerosis because of their high-performance hardware and software. Taking into account the attempts that have been made in computational techniques to simulate realistic conditions of blood flow in both diseased and healthy arteries, the present review aims to give an overview of the most recent numerical studies focused on coronary arteries, by addressing the blood viscosity models, and applied physiological flow conditions. In general, regardless of the boundary conditions, numerical studies have been contributed to a better understanding of the development of this disease, its diagnosis, and its treatment. Full article
(This article belongs to the Special Issue Computational Biofluid Mechanics)
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