The increase in cardiovascular diseases worldwide has resulted in higher death rate of people globally; the primary reason being atherosclerosis. A better understanding of this condition can be achieved through the application of numerical methods to understand the haemodynamics. The present study aims to investigate the effects of renal artery angulation on the flow characteristics in a non-critically stenosed artery compared to that of a normal artery in order to understand better, the reasons for causes and progression of renal artery stenosis. Abdominal aorta-renal artery models ranging from 30° to 90° angulations were generated from computerized tomography-angiogram slices, post which they were subjected to cleanup and defeaturing. Haemodynamic parameters such as velocity, pressure and time-averaged wall shear stress were evaluated at early systole, peak systole and peak diastole for the different artery models. Extensive amounts of flow recirculation were observed in normal renal arteries with higher bifurcating angles, whereas it was not the case in stenosed arteries where flow acceleration was seen for the duration of the cardiac cycle. Evaluation of static pressure encountered a similar trend where an increase in angulation saw a decrease in pressure for normal arteries which contradicted with stenosed artery results. Analysis of shear stress saw very similar trends in normal and stenosed arteries, with lower angulation profiles experiencing higher values of shear stress at the Ostia. In the cases of arteries of higher angulation with a non-critical stenosis, the possibility of worsening of stenosis into an opprobrious stage remains a concern.

The recent developments in computational fluid dynamics (CFD) can be useful in observing the detailed haemodynamics in renal artery bifurcation for clinical evaluation and treatment. The present study focuses on haemodynamic behaviour of blood as it flows through the abdominal aorta-renal artery junction in an idealistic healthy artery with varying bifurcation angles to the abdominal aorta, i.e. from 30° to 90° with increments of 15°. This is to examine the effect of angulation on the junction and to determine whether arterial geometry plays a role in the prediction of atherosclerotic lesions. The three-dimensional models used in this study were generated using ANSYS WORKBENCH 19.0, and numerical simulation was done using FLUENT 19.0 solver. The blood flow is assumed to be Newtonian, incompressible and laminar. Haemodynamic parameters such as velocity, wall pressure and wall shear stress along with flow variation are compared among the different models. As the angulation increased, velocity and wall shear stress at the ostial region decreased by 14% and 52% respectively. Wall pressure at the same region saw an increase by 3%. Therefore, renal arteries with higher bifurcating angles to the abdominal aorta were observed to be more prone to the formation of atherosclerotic lesions. The present study is a precursor for future studies on renal artery with stenosis.

The hybridization of composites has recently seen an exponential growth in acceptance due to its ability to improve the property such as toughness of composites. Hybridization of fibers is known to give a better balance of properties and increases the opportunity to use natural fibers, thereby reducing the impact on the environment without compromising utility. This study deals with hybridization of ultrahigh-molecular-weight polyethylene (UHMWPE) with natural fibers such as flax and jute using phenol formaldehyde as the resin. Composite panels of 4 mm thickness, comprising of eight layers were fabricated in six different fiber stack sequences using hand lay-up and compression molding techniques. The effect of stack sequence on the composites' flexural, interlaminar shear, and impact properties were investigated using scanning electron microscopy and cone beam computed tomography techniques. Composites with outer UHMWPE fibers and having flax fibers as inner core were found to have superior flexural and interlaminar shear properties of 44.45 and 5.52 MPa, respectively. Also composites with surface layers of flax fibers displayed maximum impact strength of 91.08 kJ/m 2. The results indicate that the stack sequence has a significant influence on the properties of the composite under flexural and impact loading.

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