Faculty Publications
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Publications by NITK Faculty
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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 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.