Faculty Publications
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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 Effects of the Reynolds number on two-dimensional dielectrophoretic motions of a pair of particles under a uniform electric field(Korean Society of Mechanical Engineers, 2016) Kang, S.; Mannoor, M.; Maniyeri, R.This paper presents two-dimensional direct numerical simulations to explore the effect of the Reynolds number on the Dielectrophoretic (DEP) motion of a pair of freely suspended particles in an unbounded viscous fluid under an external uniform electric field. Accordingly, the electric potential is obtained by solving the Maxwell’s equation with a great sudden change in the electric conductivity at the particle-fluid interface and then the Maxwell stress tensor is integrated to determine the DEP force exerted on each particle. The fluid flow and particle movement, on the other hand, are predicted by solving the continuity and Navier-Stokes equations together with the kinetic equations. Numerical simulations are carried out using a finite volume approach, composed of a sharp interface method for the electric potential and a direct-forcing immersed-boundary method for the fluid flow. Through the simulations, it is found that both particles with the same sign of the conductivity revolve and eventually align themselves in a line with the electric field. With different signs, to the contrary, they revolve in the reverse way and eventually become lined up at a right angle with the electric field. The DEP motion also depends significantly on the Reynolds number defined based on the external electric field for all the combinations of the conductivity signs. When the Reynolds number is approximately below Recr ? 0.1, the DEP motion becomes independent of the Reynolds number and thus can be exactly predicted by the no-inertia solver that neglects all the inertial and convective effects. With increasing Reynolds number above the critical number, on the other hand, the particles trace larger trajectories and thus take longer time during their revolution to the eventual in-line alignment. © 2016, The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.