Cell Volume Fraction Research Articles

Front-Tracking and Gelation in Sessile Droplet Suspensions: What Can They Tell Us about Human Blood?

Recently developed imaging techniques have been used to examine the redistribution of human red blood cells and comparator particles dispersed in carrier fluids within evaporating droplets. We demonstrate that progressive gelation initiates along an annular front, isolating a central pool that briefly remains open to particulate advection before gelation completes across the droplet center. Transition to an elastic solid is evidenced by cracking initiating proximal to front locations. The arrested flow of cellular components, termed a "halted front", has been investigated using a time-lapse analysis "signature". The presence of a deformable biocellular component is seen to be essential for front-halting. We show a dependence of front-halt radius on cell volume-fraction, potentially offering a low-cost means of measuring hematocrit. A simple model yields an estimate of the gel zero-shear yield-stress. This approach to understanding the drying dynamics of blood droplets may lead to a new generation of point-of-care diagnostics.

Surface-active microrobots can propel through blood faster than inert microrobots

Abstract Microrobots that can move through a network of blood vessels have promising medical applications. Blood contains a high volume fraction of blood cells, so in order for a microrobot to move through the blood, it must propel itself by rearranging the surrounding blood cells. However, swimming form effective for propulsion in blood is unknown. This study shows numerically that a surface-active microrobot, such as a squirmer, is more efficient in moving through blood than an inert microrobot. This is because the surface velocity of the microrobot steers the blood cells laterally, allowing them to propel themselves into the hole they are digging. When the microrobot size is comparable to a red blood cell or when the microrobot operates under a low Capillary number, the puller microrobot swims faster than the pusher microrobot. The trend reverses under considerably smaller microrobot sizes or high Capillary number scenarios. Additionally, the swimming speed is strongly dependent on the hematocrit and magnetic torque used to control the microrobot orientation. A comparative analysis between the squirmer and Janus squirmer models underscores the extensive applicability of the squirmer model. The obtained results provide new insight into the design of microrobots propelled efficiently through blood, paving the way for innovative medical applications.

Deposit of Red Blood Cells at low concentrations in evaporating droplets is dominated by a central edge growth

Evaporation of blood droplets and diluted blood samples is a topic of intensive research, as it is considered a potential low-cost diagnostic tool. So far, samples with a volume fraction down to a few percent of red blood cells have been studied, and these were reportedly dominated by a “coffee-ring” deposit. In this study, samples with lower volume fractions were used to investigate the growth of the evaporative deposit from sessile droplets in more detail. We observed that blood samples and salt solutions with less than 1% volume fraction of red blood cells are dominated by a central deposit. We characterized the growth process of this central deposit by evaporating elongated drops and determined that it is consistent with the Kardar-Parisi-Zhang process in the presence of quenched disorder. Our results showed a sensitivity of the deposit size to fibrinogen concentration and the shape of red blood cells, suggesting that this parameter could be developed into a new and cost-effective clinical marker for inflammation and red blood cell deformation.

Numerical-experimental estimation of the deformability of human red blood cells from rheometrical data

The deformability of human red blood cells (RBCs), which comprise almost 99% of the cells in whole blood, is largely related not only to pathophysiological blood flow but also to the levels of intracellular compounds. Therefore, statistical estimates of the deformability of individual RBCs are of paramount importance in the clinical diagnosis of blood diseases. Although the microscale hydrodynamic interactions of individual RBCs lead to non-Newtonian blood rheology, there is no established method to estimate individual RBC deformability from the rheological data of RBC suspensions, and the possibility of this estimation has not been proven. To address this issue, we conducted an integrated analysis of a model of the rheology of RBC suspensions, coupled with macrorheological data of human RBCs suspended in plasma. Assuming a nonlinear curve of the relative viscosity of the suspensions as a function of the cell volume fraction, the statistical average of the membrane shear elasticity was estimated for individual intact RBCs or hardened RBCs. Both estimated values reproduced well the experimentally observed shear-thinning non-Newtonian behavior in these suspensions. We hereby conclude that our complementary approach makes it possible to estimate the statistical average of individual RBC deformability from macrorheological data obtained with usual rheometric tests.

A nuclear jamming transition in vertebrate organogenesis.

Jamming of cell collectives and associated rigidity transitions have been shown to play a key role in tissue dynamics, structure and morphogenesis. Cellular jamming is controlled by cellular density and the mechanics of cell-cell contacts. However, the contribution of subcellular organelles to the physical state of the emergent tissue is unclear. Here we report a nuclear jamming transition in zebrafish retina and brain tissues, where physical interactions between highly packed nuclei restrict cellular movements and control tissue mechanics and architecture. Computational modelling suggests that the nuclear volume fraction and anisotropy of cells control the emerging tissue physical state. Analysis of tissue architecture, mechanics and nuclear movements during eye development show that retina tissues undergo a nuclear jamming transition as they form, with increasing nuclear packing leading to more ordered cellular arrangements, reminiscent of the crystalline cellular packings in the functional adult eye. Our results reveal an important role of the cell nucleus in tissue mechanics and architecture.

A hybrid marching cubes based IsoAlpha method for interface reconstruction

SummaryIn modelling two‐phase flows, accurate representation of interfaces is crucial. A class of methods for interface reconstruction are based on isosurface extraction, which involves a non‐iterative, interpolation based approach. These approaches have been shown to be faster by an order of magnitude than the conventional PLIC schemes. In this work, we present a new isosurface extraction based interface reconstruction scheme based on the Marching Cubes algorithm (MC), which is commonly used in computer graphics for visualizing isosurfaces. The MC algorithm apriori lists and categorizes all possible interface configurations in a single grid cell into a Look Up Table (LUT), which makes this approach fast and robust. We also show that for certain interface configurations, the inverse problem of obtaining the isovalue from the cell volume fraction is not surjective, and a special treatment is required while handling these cases. We then demonstrate the capabilities of the method through benchmark cases for 2D and 3D static/dynamic interface reconstruction.

Study on rotary bending fatigue performance of TC4 lattice structure fabricated by selective laser melting

Prediction of the fatigue performance of lattice structures in additive manufacturing still lacks widely applicable methods. To address this issue, we investigated the effect of a BCC lattice structure combined with thin walls and ribs on the fatigue performance of TC4 alloy samples. The lattice-structured samples were fabricated by selective laser melting. In addition, we proposed a prediction model of fatigue performance that combined ABAQUS finite element analysis with FE-safe fatigue analysis. The simulation and experimental results verified the reliability of the model. Based on this method, the effects of lattice and ribbed plate structures on the bending fatigue performance were investigated. The experimental results showed that the stress concentration generated by lattice structures weakened the fatigue performance. On the contrary, ribbed plates can enhance fatigue performance, which also depends on the orientation of the rib structure. The simulation results showed that increasing the volume fraction of unit cells can mitigate the stress concentration, leading to improved fatigue performance. The lattice structure combined with the rib structure exhibited superior fatigue performance. In addition, the proposed models can also be applied to other metallic materials. The findings in this study can provide a theoretical basis for the design of lattice structures with better fatigue performance.

Flexoelectric and transverse shear effects on band gaps in periodic microbeams

This paper applies wave equations and boundary conditions to a periodic electro-elastic microbeam, which incorporates transverse shear, microstructure and flexoelectric effects to anticipate the occurrence of band gaps in elastic waves. The new model has been simplified as the flexoelectric model and classical elastic model, as special cases. Meanwhile, compared to Bernoulli-Euler beam model, it is found that transverse shear effect has a significant effect on the band gap predictions of thick beams, but this effect is negligible for slender beams, indicating that this new model can be used to predict band gaps of both thick and slender beams in the high-frequency range. Furthermore, the impacts of microstructure and flexoelectric effects as well as material and microstructural parameters on band gaps are studied. The numerical results show that the influence of flexoelectricity on band gaps is the primary in the submicron beams, while the microstructure effect is the main in the micron beams. Additionally, the band gap frequencies and sizes (bandwidth) are significantly affected by the beam thickness, unit cell length and volume fraction. Thus, these discoveries demonstrate the feasibility of tailoring the band gap frequencies and sizes through the adjustment of material and microstructural parameters.

Evaluation of Scatterer Parameters From Ultrasound Scattering Models Taking Into Account Scattering From Nuclei and Cells of Cell-Pellet Biophantoms and Ex Vivo Tumors.

The Quantitative Ultrasound backscatter coefficient provides the capability to evaluate tissue microstructure parameters. Tissue-based scatterer parameters are extracted using ultrasound scattering models. It is challenging to correlate ultrasound scatterer parameters of tissue structures from optical-measured histology, possibly because of inappropriate scattering models or the presence of multiple scatterers. The objective of this study is to pursue the quantification of pertinent scatterer parameters with scattering models that consider ultrasound scattering from nuclei and cells. The concentric sphere model (CSM) and the structure factor model adapted for two types of scatterers (SFM2) are evaluated for cell-pellet biophantoms and ex vivo tumors of four cell lines: 4T1, JC, LMTK, and MAT. The structure factor model (SFM) was used for comparison. CSM and SFM2 provided scatterer parameters closer to histology (lower relative errors) for nucleus and cell radii and volume fractions than SFM but were not always accompanied by lower dispersion of the scatterer distribution (lower coefficient of variation). CSM and SFM2 quantified cell and nucleus radius and volume fraction parameters with lower relative error compared to SFM. For tumors, CSM provided better results than SFM2.

A study of non-uniform imperfect contact in shear wave propagation in a magneto-electro-elastic laminated periodic structure

The present study deals with shear wave propagation in a fully coupled Magneto-Electro-Elastic (MEE) multi-laminated periodic structure having non-uniform and imperfect interfaces. As a solution methodology, we applied a more general low-frequency dynamic asymptotic homogenization technique where the solution will be single-frequency dependent and the obtained results generalize those published in Chaki and Bravo-Castillero (Compos Struct 322:117410, 2023b) where the perfect contact case was studied. Effective homogenized dispersive equations of motion in second- and fourth-order approximations, also known as “Good” Boussinesq equations in elastic case, are derived. Local problems, closed-form expression of dispersion equations in second and fourth-order approximations and closed-form solutions of first and second local problems in second-order approximation for tri-laminated MEE periodic structure have been obtained and also validated for elastic laminates with imperfect contact case and MEE laminates with perfect contact case. The effect of non-uniform and imperfect contact, angle of incidence, unit cell size, volume fraction and ME-coupling on the wave propagation is illustrated through dispersion graphs. The effect of non-uniform and imperfect contact on dispersion curve serves as the highlight of the present work.

The effect of geometrical parameters on dimensional deviation in LPBF produced TPMS lattices: a numerical simulation based study

Triply periodic minimal surface (TPMS) lattices have drawn great attention both in academic and industrial perspective due to their outstanding mechanical behaviours. Additive manufacturing (AM) modalities enable the production of these lattices very easily. However, dimensional inaccuracy is still one of the problems that AM still faces with. Manufacturing of these lattices with AM modalities, then measuring the critical dimensions and making design changes accordingly is a costly process. Therefore, it is necessary to predict the dimensional deviation of TPMS lattices before print is a key topic. This study focused on prediction of dimensional deviation of laser powder bed fusion (LPBF) produced gyroid, diamond, primitive, IWP and Fisher-Koch lattices by using thermomechanical simulations. TPMS type, unit cell size, volume fraction, functional grading and part orientation were selected as design variables. Results showed that all the design inputs have effects on dimensional accuracy of LPBF produced parts and TPMS type has the most critical factor. Based on analysis of variance analysis, an optimum lattice configuration was proposed to obtain the lowest dimensional deviation after LPBF build.

A two-phase thin-film model for cell-induced gel contraction incorporating osmotic effects

We present a mathematical model of an experiment in which cells are cultured within a gel, which in turn floats freely within a liquid nutrient medium. Traction forces exerted by the cells on the gel cause it to contract over time, giving a measure of the strength of these forces. Building upon our previous work (Reoch et al. in J Math Biol 84(5):31, 2022), we exploit the fact that the gels used frequently have a thin geometry to obtain a reduced model for the behaviour of a thin, two-dimensional cell-seeded gel. We find that steady-state solutions of the reduced model require the cell density and volume fraction of polymer in the gel to be spatially uniform, while the gel height may vary spatially. If we further assume that all three of these variables are initially spatially uniform, this continues for all time and the thin film model can be further reduced to solving a single, non-linear ODE for gel height as a function of time. The thin film model is further investigated for both spatially-uniform and varying initial conditions, using a combination of analytical techniques and numerical simulations. We show that a number of qualitatively different behaviours are possible, depending on the composition of the gel (i.e., the chemical potentials) and the strength of the cell traction forces. However, unlike in the earlier one-dimensional model, we do not observe cases where the gel oscillates between swelling and contraction. For the case of initially uniform cell and gel density, our model predicts that the relative change in the gels’ height and length are equal, which justifies an assumption previously used in the work of Stevenson et al. (Biophys J 99(1):19–28, 2010). Conversely, however, even for non-uniform initial conditions, we do not observe cases where the length of the gel changes whilst its height remains constant, which have been reported in another model of osmotic swelling by Trinschek et al. (AIMS Mater Sci 3(3):1138–1159, 2016; Phys Rev Lett 119:078003, 2017).

Using a probabilistic approach to derive a two-phase model of flow-induced cell migration

Interstitial fluid flow is a feature of many solid tumors. In vitro experiments have shown that such fluid flow can direct tumor cell movement upstream or downstream depending on the balance between the competing mechanisms of tensotaxis (cell migration up stress gradients) and autologous chemotaxis (downstream cell movement in response to flow-induced gradients of self-secreted chemoattractants). In this work we develop a probabilistic-continuum, two-phase model for cell migration in response to interstitial flow. We use a kinetic description for the cell velocity probability density function, and model the flow-dependent mechanical and chemical stimuli as forcing terms that bias cell migration upstream and downstream. Using velocity-space averaging, we reformulate the model as a system of continuum equations for the spatiotemporal evolution of the cell volume fraction and flux in response to forcing terms that depend on the local direction and magnitude of the mechanochemical cues. We specialize our model to describe a one-dimensional cell layer subject to fluid flow. Using a combination of numerical simulations and asymptotic analysis, we delineate the parameter regime where transitions from downstream to upstream cell migration occur. As has been observed experimentally, the model predicts downstream-oriented chemotactic migration at low cell volume fractions, and upstream-oriented tensotactic migration at larger volume fractions. We show that the locus of the critical volume fraction, at which the system transitions from downstream to upstream migration, is dominated by the ratio of the rate of chemokine secretion and advection. Our model also predicts that, because the tensotactic stimulus depends strongly on the cell volume fraction, upstream, tensotaxis-dominated migration occurs only transiently when the cells are initially seeded, and transitions to downstream, chemotaxis-dominated migration occur at later times due to the dispersive effect of cell diffusion.

Analysis of the Suitability of an Effective Viscosity to Represent Interactions Between Red Blood Cells in Shear Flow.

Many methods to computationally predict red blood cell damage have been introduced, and among these are Lagrangian methods that track the cells along their pathlines. Such methods typically do not explicitly include cell-cell interactions. Due to the high volume fraction of red blood cells (RBCs) in blood, these interactions could impact cell mechanics and thus the amount of damage caused by the flow. To investigate this question, cell-resolved simulations of red blood cells in shear flow were performed for multiple interacting cells, as well as for single cells in unbounded flow at an effective viscosity. Simulations run without adjusting the bulk viscosity produced larger errors unilaterally and were not considered further for comparison. We show that a periodic box containing at least 8 cells and a spherical harmonic of degree larger than 10 are necessary to produce converged higher-order statistics. The maximum difference between the single-cell and multiple-cell cases in terms of peak strain was 3.7%. To achieve this, one must use the whole blood viscosity and average over multiple cell orientations when adopting a single-cell simulation approach. The differences between the models in terms of average strain were slightly larger (maximum difference of 6.9%). However, given the accuracy of the single-cell approach in predicting the maximum strain, which is useful in hemolysis prediction, and its computational cost that is orders of magnitude less than the multiple-cell approach, one may use it as an affordable cell-resolved approach for hemolysis prediction.

Molecular Imaging with Aquaporin-Based Reporter Genes: Quantitative Considerations from Monte Carlo Diffusion Simulations.

Aquaporins provide a unique approach for imaging genetic activity in deep tissues by increasing the rate of cellular water diffusion, which generates a magnetic resonance contrast. However, distinguishing aquaporin signals from the tissue background is challenging because water diffusion is influenced by structural factors, such as cell size and packing density. Here, we developed a Monte Carlo model to analyze how cell radius and intracellular volume fraction quantitatively affect aquaporin signals. We demonstrated that a differential imaging approach based on subtracting signals at two diffusion times can improve specificity by unambiguously isolating aquaporin signals from the tissue background. We further used Monte Carlo simulations to analyze the connection between diffusivity and the percentage of cells engineered to express aquaporin and established a mapping that accurately determined the volume fraction of aquaporin-expressing cells in mixed populations. The quantitative framework developed in this study will enable a broad range of applications in biomedical synthetic biology, requiring the use of aquaporins to noninvasively monitor the location and function of genetically engineered devices in live animals.

P15.04.A BIOLOGICAL CORRELATES OF LEAKAGE EFFECT METRICS COMPUTED FROM DYNAMIC SAGE-EPI MRI IN ENHANCING AND NON-ENHANCING HUMAN GLIOMAS

Abstract BACKGROUND Dynamic spin-and-gradient-echo echoplanar imaging (SAGE-EPI) can be used to compute novel quantitative maps derived from contrast leakage effects, which are thought to reflect tissue characteristics, while acquiring perfusion imaging. In this study, we explored leakage effect metrics and their biological correlates in human gliomas. METHODS 57 patients with histology-proven gliomas were studied (38 enhancing, 19 non-enhancing). The following quantitative leakage effect maps were computed: ΔR2,ss* (reflecting T2*-leakage effects, dependent on cytoarchitecture), ΔR1,ss (reflecting T1-leakage effects, dependent on blood-brain barrier permeability), and the transverse relaxivity at tracer equilibrium (TRATE, reflecting the balance between ΔR2,ss* and ΔR1,ss). In enhancing gliomas, these metrics were compared between patient subgroups (treatment-naïve [TN] vs recurrent [R]) and biological features (IDH status, Ki67 expression). In non-enhancing gliomas, qualitative and quantitative analyses were performed to evaluate the potential usefulness of leakage effects in the absence of gross contrast enhancement. RESULTS In enhancing IDH-wild-type gliomas (IDHwt), previous exposure to treatment determined higher ΔR1,ss (p=0.035) and lower TRATE (p=0.002). In IDH-mutant-gliomas (IDHm), previous treatment determined higher ΔR1,ss (p=0.026). In TN-gliomas, IDHwt status tended to determine higher ΔR1,ss and lower TRATE (p=0.13). ΔR1,ss values were correlated with Ktrans values (TN/R p=0.036/0.0024, r=0.68/0.59). TRATE values above 142 mM-1s-1 were exclusively seen in TN-IDHwt, and in TN-gliomas this cutoff had 89% sensitivity and 80% specificity as a predictor of Ki67>10%. Preliminary analyses on non-enhancing gliomas revealed that a subset of gliomas (n=11) showing a visual tumor-to- BACKGROUND contrast in leakage effect maps were higher in grade (p=0.049), and all grade 4 gliomas (n=2) displayed pronounced leakage effects. CONCLUSION s: In enhancing gliomas novel leakage effect metrics computed with dynamic SAGE-EPI may reflect cytoarchitecture and blood-brain barrier disruption. More in detail, TRATE was higher in IDHwt-gliomas and high-Ki67 gliomas, consistently with the hypothesis of TRATE values being proportional to cell volume fraction and cell size. ΔR1,ss was correlated to Ktrans and higher in IDHwt-gliomas and treated gliomas, consistently with the hypothesis of ΔR1,ss being a potential marker of blood-brain barrier disruption. Preliminary results on non-enhancing gliomas suggest that leakage effect metrics are more likely to be visualized in higher grades, and may be insightful in this subset despite the absence of gross contrast-enhancement. Overall, leakage effect metrics may provide insights regarding tissue characteristics with potential applications in differential diagnosis and treatment response assessment.

Application of computational fluid dynamics for simulation of stirred bioreactors in Ansys Fluent

Stirred bioreactors are widely used in the pharmaceutical industry to produce various active substances for the treatment of cancer, heart and vascular diseases, viral and bacterial infections. Despite the widespread use of bioreactors with a stirrer, the optimization of mixing conditions remains an urgent task. In bioreactors of this type, continuous mixing of cells in a medium with a high rotation speed should be carried out. The manuscript considers an example of the use of computational fluid dynamics to study and model the process of cultivation Escherichia coli bacterial cells in a batch bioreactor (NLF, 30 l.). Computational fluid dynamics was used to analyze the hydrodynamic conditions in a bioreactor with a double Rushton turbine stirrer. To describe the movement of flows and evaluate turbulence in a batch bioreactor, the multiphase Euler model and the k-𝜀 turbulence model, respectively, were used, the built-in Ansys Fluent software package. A geometric model was built with the original dimensions of the bioreactor with an NLF 30 stirrer. Based on the geometric model, a computational grid was created for the working volume of the bioreactor and the optimal parameters for constructing the computational grid were selected. As a result of modeling the hydrodynamic regime, the distribution profiles of the turbulence kinetic energy over the volume of the bioreactor were obtained and the velocities of cell movement were found at different speeds of rotation of the stirrer. The obtained results show the possibility and applicability of the Ansys Fluent software package for calculating the hydrodynamic situation in a bioreactor with a stirrer at different stirring rates and at different cell volume fractions.

Can cancer cells inform us about the tumor microenvironment?

Characteristics of the tumor microenvironment (TME) such as the leaky intratumoral vascular network and the density and composition of the desmoplastic extracellular matrix (ECM) contain essential information that determine the possibly heterogeneous interstitial fluid (IF) velocity field and interstitial fluid pressure (IFP). This information plays an important role for how anticancer drug that is delivered through the blood vasculature will distribute and possibly affect the tumor. The main question we deal with in this work is: Can we lure the cancer cells to reveal such information to us? By means of an in silico tumor model we demonstrate that subject to the condition that the tumor progression behavior is dominated by a cancer cell phenotype which moves by fluid-sensitive migration mechanisms as reported from experimental works, such information about the TME can be acquired by measuring the change in the cancer cell volume fraction distribution between two times T0 and T1, e.g., based on MRI images. We demonstrate this principle by using a continuum based multiphase model for tumor progression combined with assimilation of observed data through an ensemble Kalman filter approach which has been extensively and successfully used for updating advanced multiphase flow models in the context of reservoir simulation. Our results based on a synthetic dataset demonstrate how the methodology can be used to extract valuable quantitative information (e.g., interstitial fluid velocity field and fluid pressure, tissue conductivity reflecting ECM status, and effective vasculature conductivity) for which direct measurements may not be possible or impractical.

Hybrid material usage in TPMS forms fabricated by additive manufacturing, comparison of mechanical strength of lattices produced with AlSi10Mg and 7050

Aluminum-based cellular structures are gaining significant attention across industries due to their lightweight and impressive mechanical properties. With the advent of additive manufacturing (AM), complex periodic cellular structures with varying unit cell forms, sizes, and volume fractions can be fabricated with relative ease. In this study, the mechanical strength of lattice structures fabricated using laser powder bed fusion (LPBF) was investigated, with a focus on the effect of lattice geometry, material type, and outer wall incorporation. Results showed that both material choice and lattice geometry significantly impacted the mechanical properties of the structures. The highest ultimate strength of 400 MPa was observed in the schwartz-p geometry model created with Al 7050 LPBF alloy, with the addition of Zr identified as the key factor in enhancing its strength. The incorporation of an outer wall did not improve the strength of the structures, indicating the importance of material and geometry selection in optimizing mechanical performance. These findings provide valuable insights for the development and advancement of lattice structures in various applications and highlight the potential of additive manufacturing in this field.

Multiphase Flow Hemodynamic Evaluation of Vertebral Artery Stenosis Lesions and Plaque Stability.

Atherosclerosis is one of the main causes of vertebral artery stenosis, which reduces blood supply to the posterior circulation, resulting in cerebral infarction or death. To investigate stenosis rates and locations on the development of vertebral artery plaques. Stenosis models with varying degrees and positions of stenosis were established. The stenosis area was comprehensively analyzed using multiphase flow numerical simulation. Wall shear stress (WSS), blood flow velocity, and red blood cell (RBC) volume fraction were calculated. Blood flow velocity in 30-70% stenosis of each segment tended to increase significantly higher than normal. Downstream of 50% stenosis exhibited turbulent flow; downstream of 70% displayed reflux. Severe stenosis increases the WSS and distribution area. The mixed area of high and low WSS appeared downstream of the stenosis. The RBC volume fraction at the stenosis increased (maximum value: 0.487 at 70% stenosis in the V4), which was 1.08 times the normal volume fraction. Turbulent and backflow regions exhibited complex RBC volume fraction distributions. Flow velocity, WSS, and RBC volume fraction at the stenosis increase with stenosis severity, increasing plaque shedding. Narrow downstream spoiler and reflux areas possess low WSS and high erythrocyte volume fractions, accelerating plaque growth.