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Study of flow through arteries is gaining importance in the recent times due to onset of several cardio-vascular diseases like atherosclerosis (block in artery), aneurysms (bulging of artery), hypertension etc. The application of CFD will be useful in demonstrating the underlying mechanism of flow past the diseased arteries. In the present study, initially an approximate eccentric and concentric 50% stenosed carotid model is generated in ANSYS 12.0 based on patient data obtained from ultrasound Doppler scan. Later the percentage of stenosis is increased to 60%, 70%, 80% and 90% in both the cases. A transient analysis has been performed for several pulse cycles in ANSYS FLOTRAN for various percentage cases. The results obtained from ECN and CCN cases are compared to observe the changes in flow behavior in the downstream of stenosis as compared with normal case. The formation of vortices and flow separation zone in downstream in eccentric case is higher than in concentric case. Comparison of results concludes that, with the increase in severity of stenosis, the flow changes abruptly causing an increase in velocity and WSS at throat region. The simulation results obtained agree well with clinically observed data and available literature.

The novel coronavirus responsible for COVID-19 has spread to several countries within a considerably short period. The virus gets deposited in the human nasal cavity and moves to the lungs that might be fatal. As per safety guidelines by theWorld Health Organization (WHO), social distancing has emerged as one of the major factors to avoid the spread of infection. However, different guidelines are being followed across the countries with regards to what should be the safe distance. Thus, the current work is an attempt to understand the virus deposition pattern in the realistic human nasal cavity and also to find the impact of distance that could be termed as a safety measure. This study is performed usingComputationalFluid Dynamics as a solution tool to investigate the impact of COVID-19 deposition (i) On a realistic 3D human upper airway model and (ii) 2D social distancing protocol for a distance of 0.6, 1.2, 1.8, and 2.4 m. The results revealed that the regional deposition flux within the nasal cavity was predominantly observed in the external nasal cavity and nasopharyngeal section. Frequent flushing of these regions with saltwater substitutes can limit contamination in healthy individuals. The safe distancing limit estimated with 1 m/s airflow was about 1.8 m. The extensive deposition was observed for distances less than 1.8 m in this study, emphasizing the fact that social distancing advisories are not useful and do not take into account the external dynamics associated with airflow. [ABSTRACT FROM AUTHOR]

Introduction: In this study, Renal artery (RA) stenosis of Single Stenosed (SS) and Double Stenosed (DS) with the condition of Normal Blood Pressure (NBP) and High Blood Pressure (HBP) were investigated using the aid of Fluid Structure Interaction (FSI) approach. Methods: Numerical analysis of 3D model patient's specific abdominal aorta with RA stenosis was conducted using FSI solver in software ANSYS 18. Results: The results of velocity profile, pressure drop, time average wall shear stress (TAWSS), Oscillatory shear index (OSI) and total deformation of SS and DS with the condition of NBP and HBP were compared in terms of blood flow and structural wall tissue behaviour. The results concluded SS-NBP produced the highest value of velocity profile, TAWSS and OSI parameter compared to the others. Meanwhile, SS-HBP indicates the highest value pressure drop. On the other hand, SS-HBP and DS-HBP have a higher distribution of deformation contour and also maximum VMS compared to SS-NBP and DS-HBP. Conclusion: With the aid of FSI approach, this studied has proven that the existence of SS at RA location has a higher impact on the velocity magnitude, higher pressure drop, higher TAWSS and OSI value compared to the DS case. This is due to a high concentration of pressure acting at the narrow blood vessel of SS compared to DS cases which most of the blood flow will pass to the lower part of abdominal aorta. [ABSTRACT FROM AUTHOR]

AbstractFace cups form a vital component of breathing, assisting with devices that aid in artificial breathing for neonates. This study aims to evaluate the flow parameters in the nasal cavity for two different types of face cups. The neonatal nasal cavity model was developed from CT scans using MIMICS 21.0. Two face cups, one hemispherical and the other anatomical shaped cups are developed around the nasal cavity and the airflow is simulated using ANSYS 2021 R2. Results are compared with a nasal-only model. At the nasal valve region, the highest velocity is seen for the nasal-only model which is 16.3% higher than that of the hemispherical face cup and 15.2% superior to the anatomical-shaped face cup. In addition, the decrease in pressure across the nasal-only model is 7.4 and 6.6% below that of the hemispherical cup and anatomical cup masks. The nasal resistance values across the nasal cavity are the lowest for the nasal-only model, 7.7 and 6.7% lower respectively than the hemispherical and anatomical-shaped cups. There were very minor changes in the flow parameters such as velocity, pressure and wall shear stress when comparing the hemispherical and anatomic-shaped masks for the airflow inside the nasal cavity. [ABSTRACT FROM AUTHOR]

Objectives: The geometry of carotid bifurcation is a crucial contributing factor to the localization of atherosclerotic lesions. Currently, studies on carotid bifurcation geometry are limited to the region near to bifurcation. This study aimed to determine the influence of carotid bifurcation geometry on the blood flow using numerical simulations considering magnitude of haemodynamic parameters in the extended regions of carotid artery., Methods: In the present study, haemodynamic analysis is carried out using the non-Newtonian viscosity model for patient-specific geometries consisting of both Left and Right carotid arteries. A 3D patient-specific geometric model is generated using MIMICS, and a numerical model is created using ANSYS., Results: The results obtained from patient-specific cases are compared. The influence of geometric features such as lumen diameter, bifurcation angle, and tortuosity on the haemodynamics parameters such as velocity, WSS, pressure, Oscillatory Shear Index (OSI), and Time-Averaged Wall Shear Stress (TAWSS) are compared., Conclusion: The results demonstrate significant changes in the flow regime due to the geometric shape of the carotid artery. It is observed that the lower value of TAWSS occurs near the bifurcation region and carotid bulb region. In addition, the higher value of the (OSI) is observed in the Internal Carotid Artery (ICA) and the tortuous carotid artery region. However, it is also observed that apart from the bifurcation angle, other factors, such as tortuosity and area ratio, play a significant role in the flow dynamics of the carotid artery., Competing Interests: Declaration of Competing Interest The authors declare that they have no competing interests., (Copyright © 2024. Published by Elsevier B.V.)