Faculty Publications
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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 Aerodynamic behaviour of a linear subsonic compressor cascade in a droplet laden flow(Dalian University of Technology, 2018) Narayanan, D.; Anand, S.; Anish, S.In the present investigation a computational study of droplet laden flow in a linear compressor cascade has been carried out. Simulations have been carried out at different incidence angles in order to understand the effect of water droplets in the separated flow regions. The study reveals significant flow modifications in the separated flow region by the presence of water droplets and the total loss coefficient reduces at the downstream side of the compressor significantly at positive incidence angles. Particular emphasis has been given to study the effect of water injection on the blade loading and analyze pressure distribution over the blade at negative and positive incidence angles. It has been noted that pressure distribution over blade is almost uniform at higher incidence angles. At smaller incidence angles the blade suction side pressure values are non-uniform in the axial direction due to the increased droplet wall interactions. As a result, the pressure contours are highly non-uniform in the suction surface. On the contrary at higher incidence angles a smoother pressure contours are observed at the suction side. © 2018 by the authors of the abstracts.Item Numerical Investigation on Effects of Profiled Endwall Over Purge Flow in Linear Turbine Cascade(Springer Science and Business Media Deutschland GmbH, 2020) Babu, S.; Kiran, K.N.; Tom, J.K.; Anish, S.This paper describes the combined effects of purge flow and non-axisymmetric endwall profiling on the aerothermal performance of a linear turbine cascade. Purge slot with 45° ejection angle and three different endwall profiles, with varying hump to dip height, are analyzed. Performance of profiled endwall is compared with the non-profiled case. Reynolds-averaged Navier–Stokes (RANS) equation with SST turbulence model is used for numerical simulation. The analyzed results explore the demerits of current endwall profiles and how the transverse movement of weaker boundary layer fluid from the hub-pressure side corner enhanced. Compared to base case, endwall profiling enhanced the overturning and secondary flow kinetic energy at cascade exit. Apart from this, the profiled cases are providing very effective endwall protection compared to non-profiled purge case. © 2020, Springer Nature Singapore Pte Ltd.Item Numerical Investigation on the Effect of Various Geometries in a Solar Box-Type Cooker: A Comparative Study(Springer Science and Business Media Deutschland GmbH, 2021) Anilkumar, B.C.; Maniyeri, R.; Anish, S.The solar energy as a renewable energy has been the primary interest of many researchers for the last four to five decades due to its wide applications such as domestic cooking systems. The present study aims to investigate the effect of various box geometries such as rectangular, trapezoidal, cylindrical and frustum of a cone on the performance of solar cookers. In this study, various heat losses (convective and radiative) from the cooker cavities are analysed by simulating the condition using commercial software ANSYS16. The results of numerical analysis of rectangular cavity box-type cooker are validated by comparing with experimental results. The results show that trapezoidal cavity box-type solar cooker has higher absorber plate temperature and minimum heat losses than all other geometries operating under the same conditions. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Exergy Analysis of a Triangular Duct Solar Air Heater with Square Ribs(Springer Science and Business Media Deutschland GmbH, 2022) Nidhul, K.; Kumar, S.; Yadav, A.K.; Anish, S.The awareness about limited energy resources has urged the scientific community to scrutinize the energy conversion devices and optimize existing limited resources. In this analytical study, the exergetic performance analysis of a triangular cross-section square ribbed solar air heater (SAH) is compared with a conventional SAH. Reynolds number (Re) and temperature rise parameter (∆T/G) are varied, and their effect on exergetic efficiency is quantified. For the present study, maximum exergetic efficiency for the present study is obtained for non-dimensionalized rib height (e/D) of 0.05 and non-dimensionalized rib pitch (P/e) of 10. The optimum combinations of roughness parameters are interpreted through plots to design turbulators for triangular cross-section solar air heaters. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Influence of Purge Ejection Angles and Upstream Wakes/Disturbances on Low Aspect Ratio Turbine Blade Passage Aerodynamics(Springer Science and Business Media Deutschland GmbH, 2023) Babu, S.; Anish, S.The blade passage aerodynamics of turbine engine can be affected significantly by the purge flow—mainstream interaction. In this paper, aerodynamic behaviour of a turbine blade profile with aspect ratio 1.2 is investigated numerically, in the presence of purge flow and upstream wakes/disturbances. An effort is made to explore the effects of purge ejection angles and upstream wakes over turbine blade passage aerodynamics. Results indicates that purge flow has enhanced the cross passage pressure gradient. Presence of upstream wakes has altered the incidence angle non-uniformly throughout the span. However, strong flow acceleration of purge flow at lower ejection angles has caused significant reduction in the boundary layer cross flow and secondary flow losses. On the contrary higher ejection angles induced tangential and spanwise shifting of the loss core regions at the passage exit. The interaction of purge coolant and upstream wakes with the freestream has enhanced the secondary vortex formations within the blade passage. Additional secondary vortices are originated at the leading edge by the introduction of upstream wakes. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Computational Studies on the Hemodynamics of Patient-Specific Human Carotid Artery(Springer Science and Business Media Deutschland GmbH, 2023) Rakesh, L.; Anees Fahim, C.P.; Prakashini, K.; Anish, S.Atherosclerosis is a cardiovascular disease that affects large and medium-sized arteries and is characterised by intricate interactions between the artery wall and pulsatile blood flow. The current research focuses on the hemodynamics of the human carotid artery in both healthy and stenosed patients. Using the 3D Slicer, CT images of patients are rebuilt to get the three-dimensional geometry of the carotid artery. To further understand the effects of hemodynamic factors, computational experiments are conducted. The study used Time-Averaged Wall Shear Stress (TAWSS), OSI (Oscillating Shear Index), and RRT (Relative Residence Time) as hemodynamic parameters to characterise the flow behaviour. In this study, we have undertaken CFD studies on hemodynamic descriptors of a healthy normal artery (Case A) and unhealthy stenosed artery (Case B). The study concludes that there is a significant variation in the hemodynamic descriptors taken for study in the case of an unhealthy stenosed artery. High values of OSI and RRT are noticed in the case of an unhealthy stenosed artery. The larger magnitudes in the hemodynamic parameters indicate associated risk factors to progress and thus promotes atherosclerosis. All of these are effective in determining the loss of vascular function and the vessel tissue's integrity. For clinical diagnosis and further anatomical evidence, the indicated hemodynamics examination platform is relatively effective for clinicians. The novelty of this work is that we have used patient specific carotid artery of healthy and unhealthy artery, reconstructed artery from CT scans using appropriate medical imaging softwares, used physiological pulsatile flow for velocity input, coded an user defined function for the hemodynamic parameters like TAWSS, OSI, and RRT. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Performance Comparison of Different Geometries of Thermal Energy Storage Unit for Solar Cooker(Springer Science and Business Media Deutschland GmbH, 2023) Anilkumar, B.C.; Maniyeri, R.; Anish, S.Many researchers have been interested in solar energy as an unlimited energy resource over the last few decades due to its vast range of applications, including household cooking. The present work aims to design, optimize, fabricate, and test different geometries of thermal energy storage (TES) units for solar cooker (SC) using paraffin wax as the phase change material (PCM). The optimum amount of PCM necessary for different geometries (cylindrical, square, and hexagonal) of TES units surrounding the cooking vessel is computed using a computational approach. The TES units developed in this study have the provisions for filling the PCM on all sides, including the lid, enhancing the heat transfer to the cooking load. The performance comparison of different TES units is carried by conducting the indoor test. The experimental findings show that after 6 h, all geometries of TES units maintain the temperature of the cooking load at the melting point of PCM. However, cylindrical-shaped TES unit performs best in comparison with hexagonal and square. A cylindrical box solar cooker performance test is also carried out with an optimized cooking vessel surrounded by the PCM-filled TES unit and lid. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Effect of Induced Helicity on the Hemodynamics of Carotid Artery Passage(Springer Science and Business Media Deutschland GmbH, 2024) Rakesh, L.; Kadali, A.; Prakashini, K.; Anish, S.Abrupt narrowing of the carotid artery known as atherosclerosis is a common cardiovascular disease, increasing the risk of stroke which is one of the leading causes of death. Helicity in the arterial passage is found to be one of the effective ways to minimize plaque formation. Using Autodesk Meshmixer, an open-source software, the stenosed portion of the diseased artery is removed to obtain what is referred to in this study as the base case. The helicity and hemodynamic characteristics of a patient-specific geometry with and without stent in repaired instance are examined. The current study found that when novel stent design is placed there is a reduction in recirculation zone size and Relative Residence Time (RRT), but also resulted in increased pressure drop across the artery. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.