Faculty Publications

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    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.
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    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).
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    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.
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    Mixing in Oscillating Lid Driven Cavity—A Numerical Study
    (Springer Science and Business Media Deutschland GmbH, 2021) Neeraj, M.P.; Maniyeri, R.
    The mixing problems are highly important to be dealt with in fluid mechanics. In the present work mixing in a lid driven cavity with constant top wall velocity and oscillating top wall velocity is addressed. The staggered grid system is used and discretization of continuity equation, Navier–Stokes equations and concentration equation are done using Finite Volume Method. The Euler Explicit scheme is used for solving the numerical problem. Firstly, the developed computational model is validated with that of other researcher’s results for the case of constant top wall motion. Then the simulation is done for oscillating top wall for a Reynolds number of 100 and two amplitudes. The results in both cases are compared. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
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    Numerical Study of Double Wall Oscillating Lid Driven Cavity
    (Springer Science and Business Media Deutschland GmbH, 2023) Yaswanth, D.; Maniyeri, R.
    This paper presents a two-dimensional finite volume method-based computational model to understand the mixing phenomena in a double wall oscillating square lid driven cavity. The study is mainly performed to see the effect of Schmidt number by employing SIMPLE algorithm to solve the discretized equations of mass, momentum and concentration. The developed code in FORTRAN is validated by comparing with previous works. Numerical simulations are conducted on parallel and antiparallel wall oscillations and found that low Schmidt number provides better mixing in both cases. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
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    Numerical simulation of laminar flow past a circular cylinder
    (2009) Rajani, B.N.; Kandasamy, A.; Majumdar, S.
    The present paper focuses on the analysis of two- and three-dimensional flow past a circular cylinder in different laminar flow regimes. In this simulation, an implicit pressure-based finite volume method is used for time-accurate computation of incompressible flow using second order accurate convective flux discretisation schemes. The computation results are validated against measurement data for mean surface pressure, skin friction coefficients, the size and strength of the recirculating wake for the steady flow regime and also for the Strouhal frequency of vortex shedding and the mean and RMS amplitude of the fluctuating aerodynamic coefficients for the unsteady periodic flow regime. The complex three dimensional flow structure of the cylinder wake is also reasonably captured by the present prediction procedure. © 2008 Elsevier Inc. All rights reserved.
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    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.
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    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
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    Inverse approach for estimating boundary properties in a transient fin problem
    (Springer, 2018) Gnanasekaran, N.; Balaji, S.
    A solution methodology is proposed for an inverse estimation of boundary conditions from the knowledge of transient temperature data. A forward model based on prevalent time-dependent heat conduction fin equation is solved using a fully implicit finite volume method. First, the inverse model is formulated and accomplished for time-invariant heat flux at the fin base, and later extended to transient heat flux, base temperature and average heat transfer coefficient. Secondly, the Nusselt number is then replaced with Rayleigh number in the forward model to realistically estimate the base temperature, which varies with respect to time, based on in-house transient fin heat transfer experiments. This scenario further corroborates the validation of the proposed inverse approach. The experimental set-up consists of a mild steel 250×150×6mm3 fin mounted centrally on an aluminium base 250×150×8mm3 plate. The base is attached to an electrical heater and insulated with glass-wool to prevent heat loss to surroundings. Five calibrated K-type thermocouples are used to measure temperature along the fin. The functional form of the unknown parameters is not known beforehand; sensitivity studies are performed to determine suitability of the estimation and location of sensors for the inverse approach. Conjugate gradient method with adjoint equation is chosen as the inverse technique and the study is performed as a numerical optimization; subsequently, the estimates show satisfactory results. © 2018, Indian Academy of Sciences.
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    Numerical simulation of oscillating lid driven square cavity
    (Elsevier B.V., 2018) Indukuri, J.V.; Maniyeri, R.
    This paper aim to develop a two-dimensional computational model to study the fluid dynamic behaviour in a square cavity driven by an oscillating lid using staggered grid based finite volume method. Firstly the developed computational model is validated with that of other researcher's results for the case of finite wall motion. Later the numerical simulations are performed for the case of top wall oscillations for various combinations of Reynolds number and frequencies. From these simulations an optimum frequency is chosen and then with the optimum frequency the simulations are carried out to explore the vortex behaviour for the cases of parallel wall oscillations (both top and bottom walls moving in the same direction) and anti-parallel wall oscillations (both top and bottom walls moving in the opposite direction). From these simulations it may be concluded that Re = 1000 is medium range of operation for better mixing inside the cavity for the cases of parallel and anti-parallel wall oscillations. © 2017 Faculty of Engineering, Alexandria University