Bulletin of the American Physical Society
75th Annual Meeting of the Division of Fluid Dynamics
Volume 67, Number 19
Sunday–Tuesday, November 20–22, 2022; Indiana Convention Center, Indianapolis, Indiana.
Session T07: Red Blood Cells and Microvasculature |
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Chair: Mahdi Esmaily, Cornell University Room: 134 |
Monday, November 21, 2022 4:10PM - 4:23PM |
T07.00001: Multiscale, Cell-Resolved Simulations of Red Blood Cells in Macroscale Flows with Cell-Cell Interactions Grant J Rydquist, Mahdi Esmaily Hemolysis, or the rupture of red blood cells (RBCs), is a common issue in many blood flow problems, particularly in implanted medical devices, which often expose the RBCs to non-physically large shear stresses. While hemolysis is often estimated using empirical methods that are not generalizable to arbitrary flows, if the behavior of the actual RBCs can be accurately resolved, the results should be suitable for any flow or geometry. The purpose of this work is to construct a computational framework for accurately resolving the response of RBCs in macroscale flows. The large difference in scale between the RBCs and the macroscale flows makes direct simulations computationally infeasible; however, it is assumed that the effects of the RBCs can be modeled in the macroscale flow, for example by using a shear-thinning viscosity, leaving only the effect of the flow on the RBC. The RBCs are advected through the flow as Lagrangian tracers. At each time step, the velocity field around the cell, along with its current deformation, is used as in input into a boundary integral solver to obtain the cell's velocity. Additionally, cell-cell interactions, constituting an essential component of the motion of the cells, are especially difficult to resolve, and potential solutions are discussed. |
Monday, November 21, 2022 4:23PM - 4:36PM |
T07.00002: The effects of the endothelial surface layer on red blood cell partitioning, deformation, and penetration of that layer Jared Barber, Carlson Triebold Blood is 40-45% red blood cells by volume. This large fraction significantly affects blood flow leading to several nonlinear phenomenon including the heterogeneous distribution of red blood cells (RBCs) and the oxygen they carry. Those distributions significantly depend on how RBCs are divided or partitioned at diverging vessel bifurcations where blood flows from one vessel into two downstream vessels. Blood flow is also affected by a layer that coats vessel walls that includes a poroelastic medium known as the endothelial surface layer (ESL). Despite the importance of both RBC partitioning and the ESL, very few studies have considered both. Here we use a two-dimensional mathematical model of RBCs, the surrounding flow, and a poroelastic ESL to consider how properties of the ESL may affect RBC dynamics at diverging bifurcations. The RBCs are modeled as interconnected damped springs (viscoelastic elements) and the flow using the Stokes (viscous) flow equations. The ESL's resistance to flow (hydraulic resistivity) is modeled using a Brinkman approximation and its resistance to structural compression is modeled using a superimposed external pressure that corresponds to an osmotic pressure difference that is usually seen at ESL-flow interface. Results using lone cells passing through the bifurcation suggest that decreasing the hydraulic resistivity and compression resistance increased partitioning nonuniformity slightly (leads to more heterogeneous RBC distribution), decreased RBC deformation, decreased relative RBC velocity, and increased RBC penetration into the ESL. Additional preliminary results using pairs of cells passing through the bifurcation suggest that interaction increases partitioning nonuniformity, RBC deformation, and RBC penetration into the ESL. Increased RBC deformation has been correlated with release of vasodilators like ATP and nitric oxide while increased penetration has been correlated with more clotting. |
Monday, November 21, 2022 4:36PM - 4:49PM |
T07.00003: Cell Distributions and Segregation During Blood Flow within Straight and Serpentine Vascular Geometries in Sickle Cell Disease and Iron Deficiency Anemia Xiaopo Cheng, Christina Caruso, Wilbur A Lam, Michael D Graham The spatial distribution of different cellular components of blood is nontrivial. Red blood cells (RBCs) migrate toward vessel center leaving RBC-depleted cell-free layer (CFL) near walls, while white blood cells and platelets reside in the CFL, a flow-induced segregation called margination. The margination may have significance in some blood diseases, such as sickle cell disease (SCD) and iron deficiency anemia (IDA). A complication of SCD is chronic vasculopathy, in which endothelial cells are pro-inflammatory in the circulation. One might hypothesize that diseased cells marginate, residing in CFL, and generating physical interactions that damage endothelium. |
Monday, November 21, 2022 4:49PM - 5:02PM |
T07.00004: In vivo and in silico red blood cell lingering and partitioning in the microcirculation Alexis Darras, Yazdan Rashidi, Greta Simionato, Thomas John, Lars Kaestner, Matthias Laschke, Michael Menger, Christian Wagner Erythrocytes, also known as red blood cells, are the most abundant type of cells in the human body. Among the mechanical peculiarities of these cells are their specific shape and high flexibility. These properties are known to be critical for the cells to travel in the capillaries of our circulatory system, whose cross section is sometimes smaller than the erythrocytes diameter. It has also been shown recently that their flexibility can lead them to linger at bifurcations of the microcirculatory system. In this presentation, we discuss how to quantify the amplitude of this lingering. We applied this quantification to both in vivo measurements in the microcirculatory system of hamster and to numerical simulations. This reveals that the lingering competes with the classical Zweifach-Fung effect, which governs their partitioning through bifurcations of bigger vessels. More accurately, we demonstrate a linear correlation between the lingering amplitude and deviations from the classical model of erythrocytes partitioning from the literature. This opens new interpretation to the hinderance of microcirculation by rigidified erythrocytes. |
Monday, November 21, 2022 5:02PM - 5:15PM |
T07.00005: Cell accumulation, trapping, and oscillation in a patient-specific microcirculation network under flow Kacper Ostalowski, Jifu Tan 3D simulations on blood flow in a complex patient-specific retina vascular network were performed considering a mixture of red blood cells (RBCs), white blood cells (WBCs), and obstructed vessels. Without cells, it showed that a vessel blockage in the network might change the flow or even reverse the flow direction on distant vessels. The flow rate in some vessels could increase up to 1200% due to an obstruction. However, with cells, it showed a fluctuating flow pattern, and the cells showed complicated transport behavior at bifurcations. Cell accumulation might occur in some bifurcations such a T shaped junction. The addition of large size of WBCs reduced the local flow rate when they were squeezed through a capillary vessel, resulting a 32% flow rate reduction. The simulation of flow under stenosis with cells showed that cells could oscillate and become trapped in a vessel due to the fluctuating flow. Finally, a reduced order model (ROM) with multiple non-Newtonian viscosity models was used to simulate the blood flow in the network. Among them the Fahræus-Lindqvist model was found to be the most accurate one in terms of predicting the average hematocrit and flow rate in the network, which can be used to build a multiscale model for blood flow. |
Monday, November 21, 2022 5:15PM - 5:28PM |
T07.00006: Simulating malaria-infected blood in arterial flow to quantify changes in cell margination and immune suppression Christina E Rice, Ronald G Larson Malaria stiffens and reshapes red blood cells (RBCs), which changes the cell distribution in the vasculature. When the RBC distribution is disrupted, the ability of white blood cells and platelets to sample the endothelium wall is impeded, and the body’s immune response is affected. In order to study the effect of malaria infection on cell margination and immune suppression, we simulated artery flow as a dense cell suspension using HemoCell, an open-source immersed boundary-lattice Boltzmann method (IB-LBM) code. |
Monday, November 21, 2022 5:28PM - 5:41PM |
T07.00007: Numerical analysis of red blood cells suspension and platelets margination in curved microvessels WENBIN MAO, Mojtaba Amir Aslan Pour Our body contains about 60'000 miles of blood vessels, many of which are tortuous vessels twisting into each other. To understand the origin of the complex phenomena appearing in microvessel, it is vital to examine how blood cells move inside these vessels. Although there have been many studies in cellular flow simulations in straight vessels, there have been few studies on understanding the probable phenomena happening inside the curved ones. The current study aims to fill this gap. We used an open-source code HemoCell, which is based on the combined immersed boundary and lattice Boltzmann methods, to simulate dense suspensions of deformable red blood cells (RBC) and platelets. Various validation cases have been tested including single RBC stretching, RBC deformation in shear flow, and RBC suspension in straight microvessels. Fåhræus and Fåhræus–Lindqvist effects were investigated. Next, we discuss the simulation of cellular flow in curved microvessels with various diameters (from 20 to 64 μm), capillary numbers, and hematocrits. Comparisons have been made to understand the difference between RBC suspensions within straight and curved microvessels. We have investigated how the bending of the vessels affects relative apparent viscosity and platelet margination in detail. |
Monday, November 21, 2022 5:41PM - 5:54PM |
T07.00008: Margination of discoidal micro-sized particles in blood flow Chih-Tang Liao, Wei Chien, Yeng-Long Chen Micro-sized vascular-targeted drug carriers and imaging agents are promising for therapeutic applications. The hydrodynamics-driven migration of these micro-particles toward the vessel wall is known as margination and is the prerequisite of adhesion to the endothelial layer. Herein, we apply the lattice Boltzmann method coupled with the immersed boundary method to investigate the effect of the particle properties, vessel size, and hematocrit on the margination of discoidal polymeric micro-particles in whole blood. Experiments have shown that Leukocytes account for Young's modulus dependence of the adhesion of micro-sized particles on the vessel wall under different shear rates. On the other hand, micro-sized drug carriers can alter the dynamics of white blood cells in blood flow. We exploit our cellular-sale modeling to examine these complicated dependences. Besides, red blood cells rigidify and undergo morphological changes in diseases. We also look into the effect of red cell deformability on the margination of white blood cells and micro-sized drug carriers. |
Monday, November 21, 2022 5:54PM - 6:07PM |
T07.00009: Intravital Microscopy to Continuum In Silico Simulation of Flow-mediated Transport in Blood Clot Neighborhoods Chayut Teeraratkul, Maurizio Tomaiuolo, Timothy J Stalker, Debanjan Mukherjee Pathological blood clotting, or thrombosis, is the primary underlying cause of stroke and heart attack. Complications occur by a clot obstructing flow or embolization causing occlusion downstream. Understanding flow and flow-mediated transport in blood clot neighborhoods under physiologically realistic conditions is essential to discerning disease etiology. In silico techniques have emerged as a powerful approach to studying flow conditions in and around blood clots. Existing in silico methods, however, are often limited to idealized or static clot geometries. Here, we circumvent this limitation by bridging the gap between in silico techniques and in vivo imaging. Intravital microscopy provides a time-ordered series of high-resolution images characterizing the process of clot development in living animals. Leveraging intravital microscopy data we present an image segmentation methodology to obtain a data-driven dynamic clot configuration from mouse cremaster injury experiments. We illustrate unsteady flow and flow-mediated transport in the segmented clot neighborhood during clot development and identify coherent structures which organize advective transport around a dynamic blood clot. |
Monday, November 21, 2022 6:07PM - 6:20PM |
T07.00010: Dynamics and shape transitions of red blood cells in time-dependent capillary flow Steffen M Recktenwald, Katharina Graessel, Felix Maurer, Thomas John, Stephan Gekle, Christian Wagner Blood is mainly comprised of red blood cells (RBCs) that determine the unique flow properties of blood in the circulatory system. Their high deformability allows them to squeeze through microvessels much smaller than their equilibrium size. In microfluidic flows with channel dimensions similar to their size, RBCs exhibit characteristic shapes, such as croissants and slippers, depending on their confinement, velocity, and initial conditions. Although RBCs have been studied under steady flow conditions, knowledge about their flow behavior and shape transitions in unsteady flows remains vague. |
Monday, November 21, 2022 6:20PM - 6:33PM Author not Attending |
T07.00011: Blood flows in capillary networks Antoine G Morente, Anirudh Asuri Mukundan, Aashish Goyal, anthony wachs Modeling blood flows at the microscale is essential to improve the understanding of physiological processes occurring in capillary networks, such as vascular resistance. Progress has been made regarding 1D modeling (based on empirical correlations) or experimental techniques. Recent work (Balogh and Bagchi JCP 2017) showed results of microscale simulations of blood flows involving deformable red blood cells (RBCs) through networks of capillaries. |
Monday, November 21, 2022 6:33PM - 6:46PM |
T07.00012: The influence of the endothelial surface layer on the motion of red blood cells Ying Zhang, Thomas G Fai The endothelial lining of blood vessels presents a large surface area for exchanging materials between blood and tissues. The endothelial surface layer (ESL) plays a critical role in regulating vascular permeability, hindering leukocyte adhesion as well as inhibiting coagulation during inflammation. Once the ESL is pathologically altered, the changes in its topography are believed to cause vascular hyperpermeability and induce thrombus formation during sepsis. The occurrence of these biological phenomena requires Red Blood Cells (RBCs) stay within close proximity to the ESL, initiating RBC-layer interaction. To investigate the influence of various physical properties of the ESL on the motion of RBCs, we construct two models to represent the ESL combined with the immersed boundary method. In particular, we focus on analyzing how lift force and drag force change over time when a RBC is placed close to the ESL as the width, roughness, and permeability of the ESL vary. Our results suggest that increase in the ESL thickness has a dominant effect in slowing down the motion of RBCs for all physically-relevant permeability values, hindering the migration of RBCs from the layer; whereas effect of the roughness is minimal. |
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