Faculty Publications
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Item Numerical simulation of viscous flow past elliptic cylinder(Pleiades journals, 2019) Maniyeri, R.A study on flow over bluff bodies is a prime research problem in mechanical engineering since it helps to understand various fluid dynamics characteristics. This is a fluid–structure interaction problem which makes it challenging and complex. This paper discusses the development of a computational model to simulate the viscous flow over an elliptic cylinder. In this paper, a feedback forcing-based immersed boundary method coupled with Dirac delta function is used to construct the model. Also, two coordinates systems are employed—Lagrangian (for elliptic cylinder) and Eulerian (for fluid flow). Initially, the developed numerical model is validated. Later, the flow behavior for a fixed aspect ratio of the elliptic cylinder is studied for different Reynolds numbers. It can be seen that steady symmetric flow pattern is obtained for the range of Reynolds numbers considered in the present study. © Springer Nature Singapore Pte Ltd. 2019.Item Flow analysis for efficient design of wavy structured microchannel mixing devices(American Institute of Physics Inc. subs@aip.org, 2018) Kanchan, M.; Maniyeri, R.Microfluidics is a rapidly growing field of applied research which is strongly driven by demands of bio-technology and medical innovation. Lab-on-chip (LOC) is one such application which deals with integrating bio-laboratory on micro-channel based single fluidic chip. Since fluid flow in such devices is restricted to laminar regime, designing an efficient passive modulator to induce chaotic mixing for such diffusion based flow is a major challenge. In the present work two-dimensional numerical simulation of viscous incompressible flow is carried out using immersed boundary method (IBM) to obtain an efficient design for wavy structured micro-channel mixing devices. The continuity and Navier-Stokes equations governing the flow are solved by fractional step based finite volume method on a staggered Cartesian grid system. IBM uses Eulerian co-ordinates to describe fluid flow and Lagrangian co-ordinates to describe solid boundary. Dirac delta function is used to couple both these co-ordinate variables. A tether forcing term is used to impose the no-slip boundary condition on the wavy structure and fluid interface. Fluid flow analysis by varying Reynolds number is carried out for four wavy structure models and one straight line model. By analyzing fluid accumulation zones and flow velocities, it can be concluded that straight line structure performs better mixing for low Reynolds number and Model 2 for higher Reynolds number. Thus wavy structures can be incorporated in micro-channels to improve mixing efficiency. © 2018 Author(s).Item Computational study of fluid flow in wavy channels using immersed boundary method(Springer Verlag, 2019) Kanchan, M.; Maniyeri, R.Accurate control and handling of fluids in microfluidic-based bio-medical devices is very important in diverse range of applications such as laboratory-on-chip (LOC), drug delivery, and bio-technology. Flow through medical devices such as kidney dialyzer and membrane oxygenator can be considered as laminar due to low Reynolds number and narrow channel geometry, thus requiring efficient utilization of passive modulation systems to improve fluid mixing in these devices. In the present work, numerical investigation of fluid flow and passive mixing effects is carried out for wavy-walled channel configurations. A two-dimensional computational model based on an immersed boundary finite volume method is developed to perform numerical simulation on a staggered Cartesian grid system. Further, pressure–velocity coupling of governing continuity and Navier–Stokes equations describing the fluid flow is done by SIMPLE algorithm. Fluid variables are described by Eulerian coordinates and solid boundary by Lagrangian coordinates. Linking of these coordinate variables is done using Dirac delta function. A momentum-forcing term is added to the Navier–Stokes equation in order to impose the no-slip boundary condition on the wavy wall. Parametric study is carried out to analyze the fluid flow characteristics by varying wave geometry factor (WG Factor) of crest–crest (CC Model) wavy wall configurations for Reynolds number ranging from 10 to 50. From this work, it is evident that incorporating wavy-walled passive modulators prove to be good and robust method for enhancing mixing in biomedical devices. © Springer Nature Singapore Pte Ltd. 2019.Item Numerical Study on the Behavior of an Elastic Capsule in Channel Flow Using Immersed Boundary Method(Springer Science and Business Media Deutschland GmbH, 2020) Maniyeri, R.; Kang, S.The study of motion and dynamic behavior of elastic capsules in Poiseuille flow in a channel has become an interesting topic of research because of the wide range of applications in the field of biomedical engineering. The behavior of an elastic capsule in an externally applied flow is challenging because of the large displacement fluid–elastic structure interaction involved. In this work, we develop a computational model to capture the physics of the motion and behavior of an elastic capsule in Poiseuille flow in a channel using an immersed boundary finite volume method. The circular-shaped capsule is divided into a number of immersed boundary (IB) points. We create elastic links structure between IB points to incorporate tension/compression and bending. The flow is governed by continuity and Navier–Stokes equations which are discretized using staggered grid-based finite volume method. Dirac delta function is used to interpolate between solid (capsule) and fluid grids. Simulations are first carried out to describe the instantaneous position and shape of the capsule at a fixed Reynolds number flow in the channel. It is observed that the initial location has a significant influence in determining the final shape and position of the capsule. Further, through numerical simulations, the position and shapes of circular capsule in center-line motion with different stiffness constants for links are obtained and compared. It is found that lower elastic spring constant together with lower bending stiffness constant leads to larger deformation of the capsule because of less resistance to the flow. Also, the outcome of different Reynolds numbers (Re) on the behavior of the capsule is investigated for the center-line motion. It is noticed that the motion of the capsule retards with the increase in Reynolds number. Also, for higher value of Re, the capsule deforms less. For lower value of Re, the capsule deforms to a large extent. © 2020, Springer Nature Singapore Pte Ltd.Item Dynamics of Flexible Filament in Viscous Oscillating Flow(Springer Science and Business Media Deutschland GmbH, 2020) Kanchan, M.; Maniyeri, R.The dynamics of flexible filament in a viscous fluid is a complex fluid–structure interaction problem that has wide scientific and engineering applications in emerging fields such as biomimetics and biotechnology. Coupling the structural equations with fluid flow poses a number of challenges for numerical simulation. In this regard, techniques like immersed boundary method (IBM) have been quite successful. In the present study, a two-dimensional numerical simulation of flexible filament in a rectangular channel with an oscillating fluid flow at low Reynolds number is carried out using IBM. The discretization of governing continuity and Navier–Stokes equation is done by finite volume method on a staggered Cartesian grid. SIMPLE algorithm is used to solve fluid velocity and pressure terms. The filament mechanical properties like stiffness and bending rigidity are incorporated into the governing equation via Eulerian forcing term. An oscillating pressure gradient drives the fluid while the flexible filament is fixed to the bottom channel wall. The simulation results are validated with filament dynamic studies of previous researchers. The interaction of the filament with nearby oscillating fluid motion is well captured by the developed numerical model. © 2020, Springer Nature Singapore Pte Ltd.Item Inertial Migration of Cylindrical Particle in Stepped Channel—A Numerical Study(Springer Science and Business Media Deutschland GmbH, 2022) Neeraj, M.P.; Maniyeri, R.; Kang, S.Inertial migration of solid rigid particle in fluid flow occurs by the virtue of pure mechanical forces and it can play a pivotal role in separation techniques. The present computational study tries to capture the inertial migration dynamics of single rigid neutrally buoyant cylindrical particle in fluid flow which is residing in a stepped (sudden contraction) channel by determining the equilibrium position and migration time. The immersed boundary method based on feedback forcing scheme is used to develop the numerical model. The particle performs both translation and rotation motion according to the fluid flow condition and is modelled as rigid immersed boundary and the governing fluid momentum, and continuity equations are discretized using finite volume method in a staggered grid system and solved using semi-implicit fractional step algorithm. The study is mainly performed for centre and off-centre initial positions and its influence on the equilibrium position and migration time. It is observed that the equilibrium position is dependent on the initial position of release of particle. As initial position shifts from centre of channel, the particle equilibrium position also shifts accordingly. Further, the effect of height and length of step (contraction portion) on lateral migration is explored. The equilibrium position is found to be shifting towards the upper wall with decrease in height of step. However, the change in height of step does not have any significant effect on migration time of particle. It is identified that the increase in length of step reduces the migration time of particle although the equilibrium position remains same. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Numerical study of oscillating lid driven cavity with the presence of an obstacle using immersed boundary method(Elsevier Ltd, 2022) Yaswanth, D.; Maniyeri, R.In this paper, an oscillating lid driven cavity with an obstacle at center is simulated to study the effects on fluid mixing for various oscillating frequency (ω) and Reynolds number (Re). The oscillating lid promotes the generation of vortices and further presence of an obstacle breaks them into multiple sub-vortices which greatly enhance fluid mixing. This study is carried out to find the optimum parameters of the fluid mixing. It is performed by discretizing continuity and momentum equations using finite volume method on staggered grid system. The fluid–structure interaction is studied using feedback forcing scheme based immersed boundary method (IBM). A numerical model is developed and validated with previous results, and then simulations are carried out for different Re and ω to find the optimum for efficient fluid mixing inside the cavity. © 2022Item Numerical Simulation of Inertial Migration of Elliptical Particle Using Immersed Boundary Method(Springer Science and Business Media Deutschland GmbH, 2023) Neeraj, M.P.; Maniyeri, R.The particles suspended in a flowing fluid migrates with respect to the lift forces experienced which is generated by the virtue of the fluid. This type of movement which occurs without the aid of any external forces is known as inertial migration. The present work tries to construct a two-dimensional computational model to analyse the lateral migration of a neutrally buoyant rigid elliptical particle in Poiseuille flow which takes place in straight channel. The feedback forcing based immersed boundary methodology is adopted to build the numerical model. The inertial migration is addressed by studying the characteristics of equilibrium position and migration time. The effect of aspect ratio and initial release configuration of elliptical particle on the equilibrium position and migration time is observed with the use of the simulation results. The equilibrium is observed to be close to 0.6 times half the half of height of channel or more specifically at 0.27 for an aspect ratio of 3.333. However, with reduction in aspect ratio to 1.5 the equilibrium position shifts closer to 0.26. The decrease in aspect ratio from 3.333 to 1.5 also produces reduction in migration time from 5.906 to 4.074. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.