Special Issue "Fluid Mechanics and Heat Transfer in Biological Systems and Clinical/Medical Applications"

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

Deadline for manuscript submissions: closed (15 February 2017).

Special Issue Editors

Guest Editor
Prof. Dr. Mehrdad Massoudi

Department of Biomedical Engineering and Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213-3890, USA
Website | E-Mail
Interests: multi-component flows; non-Newtonian fluids; granular materials; heat transfer; mathematical modelling
Guest Editor
Dr. Wei-Tao Wu

Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213-3890, USA
Website | E-Mail
Interests: fluid mechanics; biophysical; blood flow; continuum mechanics

Special Issue Information

Dear Colleagues,

Bio-fluid mechanics and bio-heat transfer represent the intersection of fluid mechanics, heat transfer, biological systems and clinical/medical applications. A few examples of bio-fluid mechanics and bio-heat transfer research are: Investigation of blood flow, human cardiovascular and respiratory systems, cryosurgery, laser surgery, bio-tribology, cell transport, drug delivery, aerodynamics of birds and insects, etc. A greater understanding of the behavior of biological systems is needed in order to be able to design better medical devices, to better predict the development of diseases and to improve the treatments of a wide range of pathologies. This Special Issue of Fluids seeks original contributions or reviews in all aspects of bio-fluid mechanics and bio-heat transfer including analytical, computational and experimental studies in biological systems.

Prof. Dr. Mehrdad Massoudi
Dr. Wei-Tao Wu
Guest Editors

Manuscript Submission Information

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Keywords

  • Blood flow
  • Bio-tribology
  • Biorheology
  • Circulatory biofluid mechanics
  • Computational biology
  • Heat transfer and diffusion in tissues
  • Cardiovascular and respiratory systems
  • Fluid mechanics of heart valves
  • Drug delivery
  • Mathematical and computational modeling
  • Fluid-Solid interactions (FSI)
  • Biphasic and multiphase modeling
  • CFD applications

Published Papers (6 papers)

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Research

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Open AccessArticle
Aorta Ascending Aneurysm Analysis Using CFD Models towards Possible Anomalies
Received: 14 March 2017 / Revised: 6 June 2017 / Accepted: 8 June 2017 / Published: 10 June 2017
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Abstract
Computational fluid dynamics (CFD) can be seen as complementary tool alongside the visualization capabilities of cardiovascular magnetic resonance (CMR) and computed tomography (CT) imaging for decision-making. In this research CT images of three cases (i.e., a healthy heart pilot project and two patients [...] Read more.
Computational fluid dynamics (CFD) can be seen as complementary tool alongside the visualization capabilities of cardiovascular magnetic resonance (CMR) and computed tomography (CT) imaging for decision-making. In this research CT images of three cases (i.e., a healthy heart pilot project and two patients with complex aortic disease) are used to validate and analyse the corresponding computational results. Three 3D domains of the thoracic aorta were tested under hemodynamic conditions. Under normal conditions, the flow inside the thoracic aorta is more streamlined. In the presence of ascending aortic aneurysm, large areas of blue separation zones (i.e., low velocities) are identified, as well as an internal geometry deformation of the aortic wall, respectively. This flow separation is characterized by the reversal of flow and sudden drop of the wall shear stress (WSS) in the aorta. Moreover, the aortic aneurysm simulations adversely affect the flow by increasing the pressure drop and flow inefficiency, due to the anatomical configuration of the ascending aorta. Altered hemodynamics led to a vortex formation and locally reversed the flow that eventually induced a low flow velocity and oscillating WSS in the thoracic aorta. Significant changes in the hemodynamic characteristics affect the normal blood circulation with strong turbulence occurrence, damaging the aortic wall, leading ultimately to the need of surgical intervention to avoid fatal events. Full article
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Open AccessArticle
Large Eddy Simulation of Pulsatile Flow through a Channel with Double Constriction
Received: 26 July 2016 / Revised: 16 December 2016 / Accepted: 16 December 2016 / Published: 28 December 2016
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Abstract
Pulsatile flow in a 3D model of arterial double stenoses is investigated using a large eddy simulation (LES) technique. The computational domain that has been chosen is a simple channel with a biological-type stenosis formed eccentrically on the top wall. The pulsation was [...] Read more.
Pulsatile flow in a 3D model of arterial double stenoses is investigated using a large eddy simulation (LES) technique. The computational domain that has been chosen is a simple channel with a biological-type stenosis formed eccentrically on the top wall. The pulsation was generated at the inlet using the first four harmonics of the Fourier series of the pressure pulse. The flow Reynolds numbers, which are typically suitable for a large human artery, are chosen in the present work. In LES, a top-hat spatial grid-filter is applied to the Navier–Stokes equations of motion to separate the large-scale flows from the sub-grid scale (SGS). The large-scale flows are then resolved fully while the unresolved SGS motions are modelled using a localized dynamic model. It is found that the narrowing of the channel causes the pulsatile flow to undergo a transition to a turbulent condition in the downstream region; as a consequence, a severe level of turbulent fluctuations is achieved in these zones. Transitions to turbulent of the pulsatile flow in the post stenosis are examined through the various numerical results, such as velocity, streamlines, wall pressure, shear stresses and root mean square turbulent fluctuations. Full article
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Open AccessArticle
Reynolds Stresses and Hemolysis in Turbulent Flow Examined by Threshold Analysis
Received: 6 September 2016 / Revised: 25 November 2016 / Accepted: 13 December 2016 / Published: 21 December 2016
Cited by 2 | PDF Full-text (4747 KB) | HTML Full-text | XML Full-text
Abstract
Use of laminar flow-derived power law models to predict hemolysis with turbulence remains problematical. Flows in a Couette viscometer and a capillary tube have been simulated to investigate various combinations of Reynolds and/or viscous stresses power law models for hemolysis prediction. A finite [...] Read more.
Use of laminar flow-derived power law models to predict hemolysis with turbulence remains problematical. Flows in a Couette viscometer and a capillary tube have been simulated to investigate various combinations of Reynolds and/or viscous stresses power law models for hemolysis prediction. A finite volume-based computational method provided Reynolds and viscous stresses so that the effects of area-averaged and time-averaged Reynolds stresses, as well as total, viscous, and wall shear on hemolysis prediction could be assessed. The flow computations were conducted by using Reynolds-Averaged Navier-Stokes models of turbulence (k-ε and k-ω SST) to simulate four different experimental conditions in a capillary tube and seven experimental conditions in a Couette viscometer taken from the literature. Power law models were compared by calculating standard errors between measured hemolysis values and those derived from power law models with data from the simulations. In addition, suitability of Reynolds and viscous stresses was studied by threshold analysis. Results showed there was no evidence of a threshold value for hemolysis in terms of Reynolds and viscous stresses. Therefore, Reynolds and viscous stresses are not good predictors of hemolysis. Of power law models, the Zhang power law model (Artificial Organs, 2011, 35, 1180–1186) gives the lowest error overall for the hemolysis index and Reynolds stress (0.05570), while Giersiepen’s model (The International journal of Artificial Organs, 1990, 13, 300–306) yields the highest (6.6658), and intermediate errors are found through use of Heuser’s (Biorheology, 1980, 17, 17–24) model (0.3861) and Fraser’s (Journal of Biomechanical Engineering, 2012, 134, 081002) model (0.3947). Full article
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Open AccessArticle
Modeling the Link between Left Ventricular Flow and Thromboembolic Risk Using Lagrangian Coherent Structures
Received: 19 May 2016 / Revised: 21 October 2016 / Accepted: 15 November 2016 / Published: 22 November 2016
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Abstract
A thrombus is a blood clot that forms on a surface, and can grow and detach, presenting a high risk for stroke and pulmonary embolism. This risk increases with blood-contacting medical devices, due to the immunological response to foreign surfaces and altered flow [...] Read more.
A thrombus is a blood clot that forms on a surface, and can grow and detach, presenting a high risk for stroke and pulmonary embolism. This risk increases with blood-contacting medical devices, due to the immunological response to foreign surfaces and altered flow patterns that activate the blood and promote thromboembolism (TE). Abnormal blood transport, including vortex behavior and regional stasis, can be assessed from Lagrangian Coherent Structures (LCS). LCS are flow structures that bound transport within a flow field and divide the flow into regions with maximally attracting/repelling surfaces that maximize local shear. LCS can be identified from finite time Lyapunov exponent (FTLE) fields, which are computed from velocity field data. In this study, the goal was to use FTLE analysis to evaluate LCS in the left ventricle (LV) using velocity data obtained from flow visualization of a mock circulatory loop. A model of dilated cardiomyopathy (DCM) was used to investigate the effect of left ventricular assist device (LVAD) support on diastolic filling and transport in the LV. A small thrombus in the left ventricular outflow tract was also considered using data from a corresponding LV model. The DCM LV exhibited a direct flow of 0.8 L/cardiac cycle, which was tripled during LVAD support Delayed ejection flow was doubled, further illustrating the impact of LVAD support on blood transport. An examination of the attracting LCS ridges during diastolic filling showed that the increase is due primarily to augmentation of A wave inflow, which is associated with increased vortex circulation, kinetic energy and Forward FTLE. The introduction of a small thrombus in the left ventricular outflow tract (LVOT) of the LV had a minimal effect on diastolic inflow, but obstructed systolic outflow leading to decreased transport compared with the unobstructed LVOT geometry. Localized FTLE in the LVOT increased dramatically with the small thrombus model, which reflects greater recirculation distal to the thrombus location. The combination of the thrombus and the LVAD increased stasis distal to the thrombus, increasing the likelihood of recurring coagulation during Series flow conditions. The extension of the results of the previous studies with this analysis provides a more sensitive indicator of TE risk than the Eulerian velocity values do, and may provide an important tool for evaluating medical device design, surgical implantation, and treatment options. Full article
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Review

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Open AccessReview
A Short Review of Advances in the Modelling of Blood Rheology and Clot Formation
Received: 21 May 2017 / Revised: 19 June 2017 / Accepted: 20 June 2017 / Published: 28 June 2017
Cited by 5 | PDF Full-text (277 KB) | HTML Full-text | XML Full-text
Abstract
Several advances have taken place since the early 2000s in the field of blood flow modelling. These advances have been driven by the development of assist devices such as Left Ventricular Assist Devices (LVADs), etc., and by the acceptance of in silico tests [...] Read more.
Several advances have taken place since the early 2000s in the field of blood flow modelling. These advances have been driven by the development of assist devices such as Left Ventricular Assist Devices (LVADs), etc., and by the acceptance of in silico tests for the generation of hypotheses concerning clot formation and lysis. We give an overview of the developments in modelling of blood rheology and clot formation/lysis in the last 10 to 15 years. In blood rheology, advances are increasingly supplemented by flow simulation studies. In clot formation (or coagulation), advances have taken place in both single-scale modeling under quiescent conditions as well as in multi-scale modeling in the presence of flow. The future will possibly see more blood flow simulations in complex geometries and, simultaneously, development and simulation of multi-scale models for clot formation and lysis. Full article
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Open AccessReview
A Quasi-Mechanistic Mathematical Representation for Blood Viscosity
Received: 16 November 2016 / Accepted: 17 February 2017 / Published: 1 March 2017
Cited by 3 | PDF Full-text (3188 KB) | HTML Full-text | XML Full-text
Abstract
Blood viscosity is a crucial element for any computation of flow fields in the vasculature or blood-wetted devices. Although blood is comprised of multiple elements, and its viscosity can vary widely depending on several factors, in practical applications, it is commonly assumed to [...] Read more.
Blood viscosity is a crucial element for any computation of flow fields in the vasculature or blood-wetted devices. Although blood is comprised of multiple elements, and its viscosity can vary widely depending on several factors, in practical applications, it is commonly assumed to be a homogeneous, Newtonian fluid with a nominal viscosity typically of 3.5 cP. Two quasi-mechanistic models for viscosity are presented here, built on the foundation of the Krieger model of suspensions, in which dependencies on shear rate, hematocrit, and plasma protein concentrations are explicitly represented. A 3-parameter Asymptotic Krieger model (AKM) exhibited excellent agreement with published Couette experiments over four decades of shear rate (0–1000 s-1, root mean square (RMS) error = 0.21 cP). A 5-parameter Modified Krieger Model (MKM5) also demonstrated a very good fit to the data (RMS error = 1.74 cP). These models avoid discontinuities exhibited by previous models with respect to hematocrit and shear rate. In summary, the quasi-mechanistic, Modified-Krieger Model presented here offers a reasonable compromise in complexity to provide flexibility to account for several factors that affect viscosity in practical applications, while assuring accuracy and stability. Full article
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