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. 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. 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. 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.
13 August 2022 in Journal of Advanced Research in Fluid Mechanics and Thermal Sciences
The application of numerical methods like CFD to understand hemodynamics in arteries has excellent potential to solve complex flow problems. In recent years, CFD has been primarily used in the hemodynamics of the carotid artery due to advances in computational resources. This technique is widely used to obtain knowledge on hemodynamics, predict the risk factors for the development and progression of the atherosclerotic lesion, and analyze local flow profiles due to changes in the carotid artery geometry. This fundamental study will be supportive in observing the blood flow behavior through arteries and studying arterial diseases. The present study investigates three different subject-specific carotid bifurcation models under altered blood pressure conditions. Subject-specific 3D carotid bifurcation modeling is carried out using Materialize software. Unsteady flow simulation is conducted in ANSYS Fluent under the rigid wall and Newtonian conditions. The haemodynamic parameters such as vorticity, helicity, and time-averaged wall shear stress (TAWSS) were evaluated to understand better the beginning and progression of atherosclerotic plaques in the bifurcation. Also, the influence of geometric variation in the bifurcation region was investigated, and it was observed that this region causes significant vortex formation zones. A noticeable reduction in velocity and backflow formation was observed, which reduced the shear stress. It is established that the regions of low TAWSS along the bifurcation region are likely to develop atherosclerosis.
The output of wind energy, a vital renewable resource, has increased from 94 GW to 591 GW globally in the last ten years. Weight and cost are important considerations in wind turbine blade (WTB) design, as rotor blades make up 40%–80% of the overall weight, to fulfill the growing need for energy. Even though thermosetting composites are frequently used to make blades, they have several drawbacks, most notably that they cannot be recycled. As more blades approach the end of their lives and become unreformable once cured, recycling and disposal become more difficult, and environmental concerns increase. The main objective of the present work is to manufacture thermoplastic composites reinforced with fibers using the Vacuum Assisted Resin Infusion Moulding (VARIM) technique and assess their mechanical characteristics. The finite element analysis of the WTB incorporates the material parameters calculated for the thermoplastic resin. Test coupons are produced by shaping thermoplastic resin and fiber reinforcement using VARIM. The mechanical characteristics, including flexural and impact strength, are then assessed utilizing destructive testing techniques. Thermoset resins have good flexural properties while thermoplastic resins have better impact properties. The wind turbine blade (WTB) is simulated in ANSYS ACP based on the designated stacking sequence and fiber orientation. Static structure analysis is performed for the thermoplastic and thermosetting composites under various operating circumstances. Identification and analysis of the critical section susceptible to mechanical failure are conducted under different loading conditions, and the obtained outcome is verified. Based on the results, it is concluded that thermoplastic composites are viable materials for manufacturing wind turbine blades.
Background/Objectives: Dental cavity preparation is a critical procedure in restorative dentistry that involves the removal of decayed tissue while preserving a healthy tooth structure. Excessive stress during tooth preparation leads to enamel cracking, dentin damage, and long term compressive pulp health. This study employed finite element analysis (FEA) to investigate the stress distribution in dental structures during cavity preparation using round diamond burs of varying diameters and depths of cut (DOC). Methods: A three-dimensional human maxillary first molar was generated from computed tomography (CT) scan data using 3D Slicer, Fusion 360, and ANSYS Space Claim 2024 R-2. Finite element analysis (FEA) was conducted using ANSYS Workbench 2024. Round diamond burs with diameters of 1, 2, and 3 mm were modeled. Cutting simulations were performed for DOC of 1 mm and 2 mm. The burs were treated as rigid bodies, whereas the dental structures were modeled as deformable bodies using the Cowper–Symonds model. Results: The simulations revealed that larger bur diameters and deeper cuts led to higher stress magnitudes, particularly in the enamel and dentin. The maximum von Mises stress was reached at 136.98 MPa, and dentin 140.33 MPa. Smaller burs (≤2 mm) and lower depths of cut (≤1 mm) produced lower stress values and were optimal for minimizing dental structural damage. Pulpal stress remained low but showed an increasing trend with increased DOC and bur size. Conclusions: This study provides clinically relevant guidance for reducing mechanical damage during cavity preparation by recommending the use of smaller burs and controlled cutting depths. The originality of this study lies in its integration of CT-based anatomy with dynamic FEA modeling, enabling a realistic simulation of tool–tissue interaction in dentistry. These insights can inform bur selection, cutting protocols, and future experimental validations.
Cardiovascular disease (CVD) is one major cause of morbidity caused by the progress of atherosclerosis without any symptoms and has a high risk of Transient Ischemic Stroke (TIS). The carotid bifurcation and bulb are the region where the blood flow is irregular, which may lead to the progression of the plague. The flow disruption due to stenosis in idealised carotid artery has been extensively investigated using Fluid Structure interaction (FSI). However, the haemodynamic of patient specific carotid artery has been intensively studied. In this study, a comparison of blood flow in healthy and stenosed (80% blockage in the carotid bulb region) was carried out using Two- way FSI analysis considering non-Newtonian blood viscosity and isotropic property for vessel wall. Haemodynamic parameters such as velocity streamline, pressure, vorticity, helicity, Time-Averaged Wall shear stress (TAWSS) and Oscillatory Shear Index (OSI) were analysed along with structural parameters such as wall displacement and von Mises stress. The comparison between healthy and stenosed arteries reveals that stenosis significantly increases the velocity magnitude due to the reduced flow area caused by plaque buildup. This narrowing also results in elevated pressure upstream of the stenosis. In both healthy and stenosed arteries, maximum deformation occurs near the bifurcation at the left and right lateral sections, with the highest von Mises Stress located near the internal wall of the flow divider. In stenosed arteries, the stress magnitude is six times higher than in healthy arteries, illustrating the profound effect stenosis has on haemodynamic. Overall, the analysis emphasizes how stenosis disrupts normal blood flow and alters bio-fluid dynamics in the carotid artery