Biofluid Dynamics

2016 ◽  
Author(s):  
Clement Kleinstreuer
Keyword(s):  
2017 ◽  
Vol 313 (3) ◽  
pp. F706-F720 ◽  
Author(s):  
Subhra Nag ◽  
Andrew Resnick

Primary cilia have been called “the forgotten organelle” for over 20 yr. As cilia now have their own journal and several books devoted to their study, perhaps it is time to reconsider the moniker “forgotten organelle.” In fact, during the drafting of this review, 12 relevant publications have been issued; we therefore apologize in advance for any relevant work we inadvertently omitted. What purpose is yet another ciliary review? The primary goal of this review is to specifically examine the evidence for and against the hypothesized flow-sensing function of primary cilia expressed by differentiated epithelia within a kidney tubule, bringing together differing disciplines and their respective conceptual and experimental approaches. We will show that understanding the biophysics/biomechanics of primary cilia provides essential information for understanding any potential role of ciliary function in disease. We will summarize experimental and mathematical models used to characterize renal fluid flow and incident force on primary cilia and to characterize the mechanical response of cilia to an externally applied force and discuss possible ciliary-mediated cell signaling pathways triggered by flow. Throughout, we stress the importance of separating the effects of fluid shear and stretch from the action of hydrodynamic drag.


2001 ◽  
Vol 54 (5) ◽  
pp. 405-454 ◽  
Author(s):  
W Shyy and ◽  
M Francois ◽  
HS Udaykumar ◽  
N N’dri and ◽  
R Tran-Son-Tay

Many critical issues in biofluid dynamics occur at the boundaries between fluids, solids, or both. These issues can be very complex since in many cases the boundaries are deformable and moving. Furthermore, different characteristic times, lengths, and material properties are often present which make any computational task taxing. The present review focuses on computational modeling techniques for moving boundaries and multi-component systems with emphasis on micro-scale biofluid physics, including i) the dynamics of leukocyte (white blood cell) deformation, recovery, and adhesion; and ii) the thin-film dynamics involving tear–structure interaction in soft contact lens applications. In these problems, multiple length scales exist, and at least one of them is on the order of 10 μm or smaller. After presenting appropriate computational techniques for moving boundaries, recent research on leukocyte deformation, recovery, and adhesion is reviewed in the context of multi-component, multi-time-scale, and micro-macro interactions. The soft contact lens problem is discussed from the viewpoint of large disparities in length scales due to high aspect ratios. Depending on the nature of the problem and the goal of the computation, alternative computational techniques can successfully address the physical and numerical challenges. A major interest of this article is to stress how moving boundary techniques can be applied to provide new insights into the physico-chemical behavior of complex biological systems. To treat different time and length scales with due care in a moving boundary framework is a grand challenge in developing first-principle-based computational capabilities. There are 175 references in this review article.


Author(s):  
O.C. Zienkiewicz ◽  
R.L. Taylor ◽  
P. Nithiarasu
Keyword(s):  

Author(s):  
Charles S. Peskin ◽  
David M. McQueen
Keyword(s):  

2004 ◽  
Vol 126 (2) ◽  
pp. 188-195 ◽  
Author(s):  
S. Hyun ◽  
C. Kleinstreuer ◽  
P. W. Longest ◽  
C. Chen

Based on the hypothesis that aggravating hemodynamic factors play a key role in the onset of arterial diseases, the methodology of “virtual prototyping” of branching blood vessels was applied to diseased external carotid artery (ECA) segments. The goals were to understand the underlying particle-hemodynamics and to provide various geometric design options for improved surgical reconstruction based on the minimization of critical hemodynamic wall parameters (HWPs). First, a representative carotid artery bifurcation (CAB) and then CABs with stenosed ECAs, i.e., a distally occluded ECA and an ECA stump, were analyzed based on transient three-dimensional blood flow solutions, employing a user-enhanced commercial finite volume code. Specifically, the HWPs, i.e., oscillatory shear index, wall shear stress angle gradient, near-wall residence time of monocytes, and near-wall helicity angle difference were evaluated to compare the merits of each design option, including a reconstructed near-optimal junction which generates the lowest HWP-values. The results provide physical insight to the biofluid dynamics of branching blood vessels and guide vascular surgeons as well as stent manufacturers towards interventions leading to high sustained patency rates.


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