Browsing by Author "Anish, S."

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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. Â© Published under licence by IOP Publishing Ltd.
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.
A Numerical Analysis on Effects of Boundary Layer Fence on Blade Passage Aerodynamics and Loss Reduction
(American Institute of Physics, 2024) Babu, S.; Anish, S.
Mitigation of total pressure loss and improvement in aerodynamic performance are obtained on a low aspect ratio turbine blade. The turbine blade hub region is constructed with a boundary layer fence to reduce secondary losses. The major objective of implementing boundary layer fence is to restrict the pressure side leg of horseshoe vortex from reaching suction surface of adjacent blade. This decreases the loss associated with the passage vortex by delaying its development. Present analysis reveals the aerodynamic performance of boundary layer fence in three ways. Firstly a rectangular strip is kept close to the suction surface in order to break the suction side leg of horseshoe vortex. Secondly, to restrict the pressure side leg of horseshoe vortex from traversing from pressure surface to suction surface a fence of curved trailing edge is kept at the middle of the blade passage. In the third configuration the combined effects of both rectangular strip and fence have been analyzed. In this work the shape of the rectangular strip and fence do not follow the blade profile. Ansys-cfx, commercial software is used for numerical analysis. The results indicate that the presence of strip has resulted in the breakdown of suction side leg of horseshoe vortex and the location of fence has directed the pressure side leg of horseshoe vortex more axially rather than traversing across the blade passage. The combination of both geometries has achieved further reduction of total pressure loss coefficient. Â© 2024 American Institute of Physics Inc.. All rights reserved.
Aerodynamic behaviour of a linear subsonic compressor cascade in a droplet laden flow
(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.
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. Â© 2018 by the authors of the abstracts.
Aerodynamic performance of profiled endwalls with upstream slot purge flow in a linear turbine cascade having pressure side separation
(American Institute of Physics Inc., 2021) Babu, S.; Anish, S.
In aeroengines, purge flow directly fed from the compressor (which bypasses the combustor) is introduced through the disk space between blade rows to prevent the hot ingress. Higher quantity of purge gas fed through the wheel space can provide additional thermal protection to the passage endwall and blade surfaces. However, the interaction of purge flow with the mainstream flow leads to higher secondary losses. Secondary losses inside a turbine blade passage can be reduced effectively by endwall contouring. This paper presents computational investigation on the influence of non-axisymmetric endwall contouring over endwall secondary flow modification in the presence of purge flow with the pressure side bubble (PSB). The experimental analysis was conducted for the base case without purge and base case with purge (BCP) configurations having flat endwalls. The total pressure loss coefficient and exit yaw angle deviation were measured with the help of a five-hole pressure probe. Static pressure distribution over the blade midspan was obtained by 16 channel Scanivalve. Aerodynamic performances of three different profiled endwalls are numerically analyzed and are compared against the BCP configuration. The effects of different contoured endwall geometries on endwall static pressure distribution and secondary kinetic energy were also discussed. Analysis shows that in the first contoured endwall configuration (EC1), the formation of stagnation zones at a contour valley close to the suction surface causes the exit total pressure loss coefficient to increase. The shifting of the contour valley near to the pressure surface (EC2 configuration) has resulted in local acceleration of the diverted pressure side leg of the horseshoe vortex over the hump toward the end of the passage. In the third configuration (EC3 configuration), reduced valley depth and optimum hump height have effectively redistributed the endwall pitchwise pressure gradient. The increased static pressure coefficient at the endwall near to the pressure surface has eliminated the PSB formation. In addition, computational results of unsteady Reynolds averaged Navier-Stokes simulations are obtained for analyzing transient behavior of PSB, with more emphasis on its migration on the pressure surface and transport across the blade passage. The additional work done by the mainstream fluid to transport the low momentum PSB fluid has caused higher aerodynamic penalty at the blade exit region. In this viewpoint, the implementation of contoured endwalls has shown beneficial effects by eliminating the PSB and related secondary vortices. At 27% of axial chord downstream of the blade trailing edge, a 4.1% reduction in the total pressure loss coefficient was achieved with endwall contouring. © 2021 Author(s).
An aerothermal investigation of purge flow behaviour in a linear turbine cascade with upstream wakes
(Bentham Science Publishers, 2018) Babu, S.; Anish, S.
Background: Over all efficiency of a turbofan engine can be improved by increasing turbine inlet temperature. To withstand the high turbine inlet temperatures advanced cooling techniques and robust materials are required. Air supplied from compressor can be used to purge turbine components and disk cavities from the incoming hot gas. Objective: In the present study, an attempt is made to understand the aerodynamic and thermal effects caused by the purge flow in the presence of stationary upstream wakes. Methods: Reynolds Averaged Navier Stokes Equation coupled with SST turbulence model is used for computational study. Base case experimental data conducted on a 5 blade linear cascade is used for numerical validation. The coolant to mainstream blowing ratio is varied from 0.2 to 1.2 with a step size of 0.2. Results: It is observed that with an increase in the blowing ratio, the mass averaged total pressure losses also increase. Purge flow shifts the passage vortex away from the endwall and causes significant overturning up to a span of 30-40mm, before they exhibit underturning up to midspan. In an effort to reduce the losses, purge ejection angle is reduced to 45° from 90°. Significant loss reduction and improved endwall protection are observed at 45° ejection angle. This ejection angle provides enough acceleration and momentum to the fluid inside the endwall boundary layer. But the upstream secondary wakes and secondary flows enhanced the mixing losses within the blade passage. Conclusion: The turbulent mixing generated by upstream wakes reduced the film cooling effectiveness over the endwall. The numerical results show that film cooling effectiveness can be improved by reducing the purge ejection angle. Various patents have been discussed in this article. © 2018 Bentham Science Publishers.
An investigation on the effect of pitchwise endwall design in a turbine cascade at different incidence angles
(Elsevier Masson SAS 62 rue Camille Desmoulins Issy les Moulineaux Cedex 92442, 2017) Kiran, K.N.; Anish, S.
This paper describes the effects of non-axisymmetric endwall profiling on the aerodynamic performance of a linear turbine cascade at different incidence angles. The sinusoidal profiling is carried out with constant profile curvature along the mean streamline path. Three different profiles, with varying hump to dip height, are analyzed numerically and the performances are compared with the planar profile. Reynolds Averaged Navier Stokes (RANS) equations are solved in their conservative form using Finite Volume Method with SST turbulence model. The calculated results indicate that the profiled endwall minimizes the lateral movement of weaker boundary layer fluid from the hub-pressure side corner. In comparison with planar case, the flow deviations are largely contained with endwall profiling but closer to the endwall it enhances the overturning and secondary flow kinetic energy. The reduction in loss coefficient is estimated to be 1.3%, 8.7% and 38% for incidence angles of ?10°, nominal and +15° respectively. The sinusoidal profiling has brought down the pitch averaged flow deviation and secondary flow kinetic energy at nominal and positive incidence angles but the impact is insignificant at negative incidence. Profiling minimizes the rolling up of the passage vortex and makes the passage vortex to migrate closer to the endwall. This flow modification brings down the losses in the core flow but enhances the losses near the endwall. © 2017 Elsevier Masson SAS
AN ITERATIVE ALGORITHM FOR DESIGNING AND SCALING OF PARABOLIC TROUGH COLLECTOR BASED SOLAR AGRO-DRYING SYSTEM
(Begell House Inc., 2025) Kabeer, V.P.A.; Maniyeri, R.; Anish, S.
This work proposes a simple and robust iterative algorithm for designing and scaling an indirect solar agro-drying system, which harvests thermal energy for drying using a parabolic trough collector (PTC). Separate computational procedures are developed for the design of the PTC by considering receiver tubes with and without a glass envelope. The computational procedure starts with the total heat requirement in the drying chamber and considers various heat losses and heat loss coefficients for the PTC receiver tube. The equations for various modes of heat losses in receiver tubes with and without a glass envelope are identified and formulated. Using thermal network and heat balance analysis, the expressions for various heat losses and overall heat loss coefficient are formulated in both cases. Required aperture area for the reflector surface of the PTC can be obtained in terms of overall heat loss coefficient and the collector heat removal factor. The tedious equations involved in computational procedure are solved using an iterative algorithm by developing a code in MATLAB. The results obtained from parametric analysis conducted using computational procedure reveals that heat losses and area of PTC required for providing drying thermal energy will be more if the receiver tube of PTC is without glass cover. The iterative algorithm described here can be used to optimize the design parameters and thus helps researchers in designing and sizing the components required for drying agro-based products. The algorithm will also help to scale the size of PTC and drying chamber based on the quantity and item to be dried. © 2025 by Begell House, Inc.
A comparative CFD study on the hemodynamics of flow through an idealized symmetric and asymmetric stenosed arteries
(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.
Computational and experimental studies on the development of an energy-efficient drier using ribbed triangular duct solar air heater
(Elsevier Ltd, 2020) Nidhul, K.; Kumar, S.; Yadav, A.; Anish, S.
Triangular duct cross-section is introduced for solar air heater (SAH) of an indirect type of solar dryer (ITSD). Using computational study, the thermo-hydraulic performance of triangular duct SAH with inclined ribs for varying rib inclination (30° < ? < 75°) in the turbulent flow regime (5000 < Re < 17500) is studied. With the rib configuration providing maximum thermos-hydraulic performance, a ribbed rectangular duct SAH is designed, and the performance of the same is compared to the former for similar heat input. Results show that the ribbed (? = 45°) triangular duct has 17% higher effectiveness compared to the latter and 79% when compared to smooth SAH. Ribs in triangular duct solar air heater facilitate the increase in temperature even in the core of the duct, delivering the air at 6 K additional temperature relative to a rectangular ribbed duct for same heat input and flow Re. The superiority of the ribbed triangular SAH is further confirmed by studying the drying characteristics of Okra and two variants of banana, namely Nendran and Robusta for the maximum temperature obtained at the outlet of the respective SAH. Various thin layer drying models available in the literature were analyzed, and Modified page model represented the drying behaviour with R2 = 0.99. For ITSD, ribbed triangular duct SAH exhibits a maximum of 60.3% reduction in moisture ratio with a maximum increase of 97.9% increase in average values of diffusivity coefficient confirming that it is an energy-efficient design for an ITSD. © 2020 International Solar Energy Society
Computational investigation on secondary flows in a linear turbine cascade with tapered dual fence
(Korean Society of Mechanical Engineers, 2019) Kiran, K.N.; Babu, B.; Anish, S.
The focus of the present work is to minimize the secondary flow losses inside a linear turbine cascade by means of a novel design of streamwise dual fence. The leading edge and trailing edge of the fences have been modified so as to reduce the total pressure loss coefficient in the passage. The study has been carried out computationally based on RANS simulations with SST turbulence model. Numerous simulations have been undertaken with single fence and dual fence models and compared with the base case model. The dual fence model with tapered trailing edge exhibits significant loss reduction compared to the base case. A suitable fence height ratio (FHR) has been identified for the dual fence model. The FHR = 2 configuration reduces the secondary flow kinetic energy by 78 % within the blade passage and it reduces the exit angle deviation significantly throughout the span. Detailed flow field analysis has been carried out to understand the physical mechanism behind the loss reduction with dual fence models. It is observed that fence-1 breaks the pressure side leg of the horse shoe vortex at the beginning of their formation itself. The radial penetration of the suction side leg of the horse shoe vortex is restrained by fence-2. These combined effects prevent the formation and mixing of two prominent loss core regions thereby avoiding the accumulation of low energy fluid near the suction side of blade. © 2019, KSME & Springer.
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.
Computational predictions of velocity ratio and ejection angle on purge flow in a linear turbine cascade with upstream disturbance
(Isfahan University of Technology secretary@jafmonline.net, 2020) Babu, S.; Anish, S.
Secondary air bled from the compressor which bypasses the combustion chamber is used to seal the turbine components from incoming hot gas. Interaction of this secondary air or purge flow with the mainstream can alter the flow characteristics of turbine blade passage. An in depth analysis of secondary loss generation by purge flow in the presence of upstream disturbances has huge relevance. The objective of present study is to understand the aerodynamic and thermal effects caused by the purge coolant flow in the presence of an upstream wake. A linear turbine cascade is selected for the computational study and a stationary cylindrical rod which resembles the trailing edge of nozzle guide vane is kept 20 mm before the leading edge to generate the upstream wake (or disturbance). Purge flow disturbances includes strong formation of Kelvin-Helmholtz vortices at trailing edge and additional roll-up vortices at leading edge. Detailed analysis is carried out by varying the velocity ratios as well as the ejection flow angle. Higher velocity ratio and perpendicular coolant ejection reduces the mainstream axial momentum which enhances the passage cross flow. Even though the mass averaged total pressure loss is linearly dependent on the velocity ratio, a reduction in the ejection angle brings down the loss coefficient at the blade exit. A lower ejection angle will improve the film cooling effectiveness also. The presence of purge flow causes an increase in the overturning and underturning. © Isfahan University of Technology.
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. Â© 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Computational study of radial gap effect between impeller and diffuser on the unsteadiness of vaned diffuser in a centrifugal compressor
(Korean Society of Mechanical Engineers, 2017) Anish, S.; Sitaram, N.
Understanding the unsteady fluid dynamics inside the diffuser holds the key to improve the performance of centrifugal compressor. A detailed computational study has been conducted in a low-speed centrifugal compressor to understand the unsteady flow mechanisms that govern the static pressure recovery inside the vaned diffusers. Simulations are carried out for three different leading edge locations at design and off-design conditions. The study is carried out using Reynolds-averaged Navier-Stokes simulations. This study revealed that the unsteady fluctuations exhibit contrasting behavior at different radial gaps and flow coefficients. An optimum radial gap is strictly a function of the stage loading. A high radial gap helps contain the fluctuations at low flow coefficients, but it enhances the fluctuations at high flow coefficients. If the leading edge is kept close to the impeller blade, then the above design flow coefficient of the vaned passage facilitates a reduction in the unsteady fluctuations. On the contrary, keeping the leading edge close to the impeller blade can accelerate the unsteady fluctuations at low flow coefficients. © 2017, The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany, part of Springer Nature.
Critical review of ribbed solar air heater and performance evaluation of various V-rib configuration
(Elsevier Ltd, 2021) Nidhul, K.; Yadav, A.K.; Anish, S.; Kumar, S.
The low heat transfer rate in a flat plate solar air heater (SAH) is due to the development of a laminar sub-layer near the heated absorber plate. Owing to this, the plate temperature rises substantially, instigating losses and thus reducing the efficiency. Extensive research has been carried out to mitigate this problem, of which passive technique emerged to be a promising solution. The passive method involves the application of fins/turbulators/ribs on the surface where the boundary layer develops so that it breaks the same. Various profiles and configurations of the ribs ranging from transverse to inclined and continuous to discrete have been presented concisely. Correlations on Nusselt number (Nu) and friction factor (f) for different rib configurations have been summarized in order so that it can be accessed for future research. 3-D CFD analysis is carried out to gain insight into the flow pattern of various V-ribbed SAH, and with the help of streamlines and contours, the findings are established. Furthermore, various exergy destruction has been studied in detail for different V-rib configurations, namely– V-rib, multiple V-rib, and multiple V-rib with the gap, and analyzed in detail for prospective studies. Exergetic performance study of these rib configurations indicates that the multiple ribs and the multiple rib-gap combinations enhance exergetic efficiency (ηex) by 12% and 31.6%, respectively, in comparison to V-rib SAH. © 2021 Elsevier Ltd
Design, fabrication and performance assessment of a solar cooker with optimum composition of heat storage materials
(Springer Science and Business Media Deutschland GmbH, 2021) Anilkumar, B.C.; Maniyeri, R.; Anish, S.
Solar energy as an inexhaustible source of 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 current work aims to determine the optimum cooker surface area with the aid of analytical heat loss and design equations. The top, bottom and side heat loss coefficients are calculated by an iterative procedure solved using MATLAB. Also, it seeks to obtain the performance parameters of a solar cooker having sensible heat storage materials. For an anticipated average solar irradiation of 800 W/m2 and for boiling 1.5 kg mass of water, the cooker surface area is found to be 0.36 m2 and fabricated accordingly. Also, in this study, iron grits, sand, brick powder and charcoal powder are taken in the optimum ratio (mass) of 1:2:2:3 respectively as heat storage material. The performance indicators namely first and second figures of merit (F1 and F2), thermal and exergy efficiency are found to be 0.085, 0.319, 16.1% and 0.61% respectively. It is found that water temperature in the developed thermal energy storage incorporated solar cooker is maintained above 70 °C until 6 PM in a day. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.
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.
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. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.