Faculty Publications
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Publications by NITK Faculty
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Item A computational study on the stenosis circularity for a severe stenosed idealized artery(Pleiades journals, 2019) Prashantha, B.; Anish, S.Narrowing of blood vessels (stenosis) changes the nature of blood flow through the arteries. The altered flow structures at the downstream of stenosis may generate adverse effects on the arterial wall. Hence, an understanding of the effect of stenosis circularity on the flow behavior at the downstream of stenosis is clinically beneficial. The present study has been carried out on idealized stenosed artery model with severe case of stenosis (75% area reduction) but with the same cross-sectional area that has been selected for the study. The effect of different physiological states (pulse rates) study has been examined through using FLUENT Inc. solver by finite volume method, controlled through user-defined functions. The results indicate that the velocity profiles, oscillatory shear stress, and fluid residence time are significantly affected by the shape of the stenotic region. Fluid residence time in the downstream plays a significant role in understanding the hotspots for the secondary deposition/plaque. © Springer Nature Singapore Pte Ltd. 2019.Item A comparative CFD study on the hemodynamics of flow through an idealized symmetric and asymmetric stenosed arteries(Institute of Physics Publishing helen.craven@iop.org, 2017) Prashantha, B.; Anish, S.The aim of the present study is to numerically evaluate the hemodynamic factors which affect the formation of atherosclerosis and plaque rupture in the human artery. An increase of atherosclerosis in the artery causes geometry changes, which results in hemodynamic changes such as flow separation, reattachment and adhesion of new cells (chemotactic) in the artery. Hence, geometry plays an important role in the determining the nature of hemodynamic patterns. Influence of stenosis in the non-bifurcating artery, under pulsatile flow condition has been studied on an idealized geometry. Analysis of flow through symmetric and asymmetric stenosis in the artery revealed the significance of oscillating shear index (OSI), flow separation, low wall shear stress (WSS) zones and secondary flow patterns on plaque formation. The observed characteristic of flow in the post-stenotic region highlight the importance of plaque eccentricity on the formation of secondary stenosis on the arterial wall. © Published under licence by IOP Publishing Ltd.Item Discrete-Phase Modelling of an Asymmetric Stenosis Artery Under Different Womersley Numbers(Springer Verlag, 2019) Prashantha, B.; Anish, S.Understanding the hemodynamics in the post-stenotic region of an asymmetric stenosis is of paramount importance in the study of atherosclerosis progression. Numerically, the analysis becomes more complex when a discrete phase is added to the continuous phase in order to understand the behaviour of atherogenic particles in a pulsatile flow environment. In the present study, discrete-phase modelling (DPM) of an asymmetric and symmetric stenosed artery models has been carried out at different Womersley numbers. The objective is to understand the correlation between the discrete-phase (atherogenic) particle behaviour with the characteristics of continuous phase (blood) under varying pulse frequencies. Continuous phase is modelled by time-averaged Navier–Stokes equations and solved by means of pressure implicit splitting of operators algorithm. DPM has been carried out with one-way coupling. The transport equations are solved in the Eulerian frame of reference, and the discrete phase is simulated in Lagrangian frame of reference. The study brings out the importance of helicity in the atherosclerosis progression. Result shows that the asymmetric stenosis model exhibits less helical flow structure and the vortical structures are not getting transported to the downstream. Consequently, the average particle residence time (PRT) of the atherogenic particles is one order higher than the symmetric stenosis model. Low PRT leads to enhanced mass transport in the arterial flow and triggers further occlusion/plaque build-up at the post-stenotic region. The extent of asymmetry in a diseased artery may be considered as a useful parameter in understanding the rate of progression of atherosclerosis. © 2018, King Fahd University of Petroleum & Minerals.Item Computational investigations on the hemodynamic performance of a new swirl generator in bifurcated arteries(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2019) Prashantha, B.; Anish, S.Hemodynamic behaviour of blood in the bifurcated arteries are closely related to the development of cardiovascular disease. The secondary flows generated at the bifurcation zone promotes the deposition of atherogenic particles on the outer walls. The present study aims at suppressing the development of atherosclerosis plaque by inducing helical flow structure in the arterial passage. To realize this objective a novel swirl generator (stent like structure with an internal groove) has been developed to induce helicity in the bifurcated passage. The functional requirement of the swirl generator is to minimize the relative residence time (RRT) of the fluid layer near the endothelial wall without generating any additional pressure drop. Different configurations of the swirl generator have been tested computationally using large eddy simulation (LES) model. It is observed that the induced helical flow redistributes the kinetic energy from the centre to the periphery. A single rib swirl flow generator proximal to the stent treated passage can generate sufficient helicity to bring down the RRT by 36% without generating any additional pressure drop. The swirl flow adds azimuthal instability which increase vortex formations in the passage. The induced helical flow in the domain provokes more linked vortices, which may act as self-cleaning mechanism to the arterial wall. © 2018, © 2019 Informa UK Limited, trading as Taylor & Francis Group.