scholarly journals Continuum Scale Non Newtonian Particle Transport Model for Hæmorheology

Mathematics ◽  
2021 ◽  
Vol 9 (17) ◽  
pp. 2100
Author(s):  
Torsten Schenkel ◽  
Ian Halliday
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Particle Transport ◽  
Transport Model ◽  
Model Parameters ◽  
Newtonian Viscosity ◽  
Small Vessels ◽  
Continuum Scale ◽  
Particle Transport Model ◽  
Meso Scale

We present a continuum scale particle transport model for red blood cells following collision arguments, in a diffusive flux formulation. The model is implemented in FOAM, in a framework suitable for haemodynamics simulations and adapted to multi-scaling. Specifically, the framework we present is able to ingest transport coefficient models to be derived, prospectively, from complimentary but independent meso-scale simulations. For present purposes, we consider modern semi-mechanistic rheology models, which we implement and test as proxies for such data. The model is verified against a known analytical solution and shows excellent agreement for high quality meshes and good agreement for typical meshes as used in vascular flow simulations. Simulation results for different size and time scales show that migration of red blood cells does occur on physiologically relevany timescales on small vessels below 1 mm and that the haematocrit concentration modulates the non-Newtonian viscosity. This model forms part of a multi-scale approach to haemorheology and model parameters will be derived from meso-scale simulations using multi-component Lattice Boltzmann methods. The code, haemoFoam, is made available for interested researchers.

scholarly journals Mathematical Models for Some Aspects of Blood Microcirculation

Symmetry ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1020
Author(s):  
Angiolo Farina ◽  
Antonio Fasano ◽  
Fabio Rosso
Keyword(s):  
Blood Flow ◽  
Mathematical Models ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Blood Rheology ◽  
Small Class ◽  
Small Vessels ◽  
Blood Microcirculation ◽  
Peculiar Behavior

Blood rheology is a challenging subject owing to the fact that blood is a mixture of a fluid (plasma) and of cells, among which red blood cells make about 50% of the total volume. It is precisely this circumstance that originates the peculiar behavior of blood flow in small vessels (i.e., roughly speaking, vessel with a diameter less than half a millimeter). In this class we find arteriolas, venules, and capillaries. The phenomena taking place in microcirculation are very important in supporting life. Everybody knows the importance of blood filtration in kidneys, but other phenomena, of not less importance, are known only to a small class of physicians. Overviewing such subjects reveals the fascinating complexity of microcirculation.

EFFECT OF STENOSIS SEVERITY ON SHEAR-INDUCED DIFFUSION OF RED BLOOD CELLS IN CORONARY ARTERIES

2019 ◽  
Vol 19 (05) ◽  
pp. 1950034 ◽  
Author(s):  
ABDULRAJAK BURADI ◽  
SUMANT MORAB ◽  
ARUN MAHALINGAM
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Mixture Theory ◽  
Theory Approach ◽  
Newtonian Viscosity ◽  
Maximum Fluctuation ◽  
Stenosis Severity ◽  
Flux Model ◽  
First Time ◽  
Arterial Endothelial Cells

In large blood vessels, migration of red blood cells (RBCs) affects the concentration of platelets and the transport of oxygen to the arterial endothelial cells. In this work, we investigate the locations where hydrodynamic diffusion of RBCs occurs and the effects of stenosis severity on shear-induced diffusion (SID) of RBCs, concentration distribution and wall shear stress (WSS). For the first time, multiphase mixture theory approach with Phillips shear-induced diffusive flux model coupled with Quemada non-Newtonian viscosity model has been applied to numerically simulate the RBCs macroscopic behavior in four different degrees of stenosis (DOS) geometries, viz., 30%, 50%, 70% and 85%. Considering SID of RBCs, the calculated average WSS increased by 77.70% which emphasises the importance of SID in predicting hemodynamic parameters. At the stenosis throat, it was observed that 85% DOS model had the lowest concentration of RBCs near the wall and highest concentration at the center. For the stenosis models with 70% and 85% DOS, the RBC lumen wall concentration at the distal section of stenosis becomes inhomogeneous with the maximum fluctuation of 1.568%. Finally, the wall regions with low WSS and low RBC concentrations correlate well with the atherosclerosis sites observed clinically.

scholarly journals Silent hypoxia: higher NO in red blood cells of COVID-19 patients

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Esmaeil Mortaz ◽  
Majid Malkmohammad ◽  
Hamidreza Jamaati ◽  
Parisa Adimi Naghan ◽  
Seyed MohamadReza Hashemian ◽  
...  
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Diffuse Alveolar Damage ◽  
Serum Levels ◽  
Pulmonary Involvement ◽  
Clinical Feature ◽  
Control Group ◽  
Small Vessels ◽  
Control Subjects ◽  
Healthy Control

Abstract Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes coronavirus disease 2019 (COVID-19) has spread to almost 100 countries, infected over 31 M patients and resulted in 961 K deaths worldwide as of 21st September 2020. The major clinical feature of severe COVID-19 requiring ventilation is acute respiratory distress syndrome (ARDS) with multi-functional failure as a result of a cytokine storm with increased serum levels of cytokines. The pathogenesis of the respiratory failure in COVID-19 is yet unknown, but diffuse alveolar damage with interstitial thickening leading to compromised gas exchange is a plausible mechanism. Hypoxia is seen in the COVID-19 patients, however, patients present with a distinct phenotype. Intracellular levels of nitric oxide (NO) play an important role in the vasodilation of small vessels. To elucidate the intracellular levels of NO inside of RBCs in COVID-19 patients compared with that of healthy control subjects. Methods We recruited 14 COVID-19 infected cases who had pulmonary involvement of their disease, 4 non-COVID-19 healthy controls (without pulmonary involvement and were not hypoxic) and 2 hypoxic non-COVID-19 patients subjects who presented at the Masih Daneshvari Hospital of Tehran, Iran between March–May 2020. Whole blood samples were harvested from patients and intracellular NO levels in 1 × 106 red blood cells (RBC) was measured by DAF staining using flow cytometry (FACS Calibour, BD, CA, USA). Results The Mean florescent of intensity for NO was significantly enhanced in COVID-19 patients compared with healthy control subjects (P ≤ 0.05). As a further control for whether hypoxia induced this higher intracellular NO, we evaluated the levels of NO inside RBC of hypoxic patients. No significant differences in NO levels were seen between the hypoxic and non-hypoxic control group. Conclusions This pilot study demonstrates increased levels of intracellular NO in RBCs from COVID-19 patients. Future multi-centre studies should examine whether this is seen in a larger number of COVID-19 patients and whether NO therapy may be of use in these severe COVID-19 patients.

scholarly journals Forecasting Solar Energetic Particle Fluence with Multi-Spacecraft Observations

2017 ◽  
Vol 13 (S335) ◽  
pp. 298-300 ◽  
Author(s):  
T. Laitinen ◽  
S. Dalla ◽  
M. Battarbee ◽  
M. S. Marsh
Keyword(s):  
Particle Transport ◽  
Energetic Particle ◽  
Transport Model ◽  
Solar Energetic Particle ◽  
Time Estimates ◽  
Single Location ◽  
Model Predictions ◽  
Solar Eruptions ◽  
Order Of Magnitude ◽  
Particle Transport Model

AbstractForecasting Solar Energetic Particle (SEP) fluence, as integrated over an SEP event, is an important element when estimating the effect of solar eruptions on humans and technology in space. Current real-time estimates are based on SEP measurements at a single location in space. However, the interplanetary magnetic field corotates with the Sun approximately 13° each day with respect to Earth, thus in 4 days a near-Earth spacecraft will have changed their connection about 60° from the original SEP source. We estimate the effect of the corotation on particle fluence using a simple particle transport model, and show that ignoring corotation can cause up to an order of magnitude error in fluence estimations, depending on the interplanetary particle transport conditions. We compare the model predictions with STEREO observations of SEP events.

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