Pardha Saradhi

National University of Singapore | NUS · Department of Mechanical Engineering

Wind tunnel experimentations have played a vital role in determining the aerodynamic loads for the design of aircrafts, tall buildings, bridges, etc. With the advent of unmanned and autonomous flying devices, the role of wind tunnel testing becomes even more critical. The role will now not only include determining the aerodynamic loads but also tes...

Two-dimensional numerical simulations have been performed to understand the effect of wall proximity on the vortex-induced vibrations (VIV) of an elastically mounted circular cylinder having two degrees of freedom for gap ratios g/D = {0.1,0.2,0.3,0.4,0.5,0.6}, where D is the cylinder diameter, and g is the gap between the cylinder's bottom surface...

In this study, we present two and three-dimensional numerical investigation to understand the combined effects of the non-dimensional heave amplitude varying from 0 to 1 and the pitch amplitude ranging from 0° to 30° on the propulsive performance for a single and tandem foil system at Reynolds number 1100 and reduced frequency 0.2. We initially pre...

Accuracy and numerical stability of nonlinear coupled fluid-elastic interaction simulations largely depends on the coupling and interface modeling algorithms. As part of the numerical coupling, the coupled solver requires to satisfy the kinematic and dynamic continuity conditions along the interface in addition to the fluid and structural dynamics...

Two-phase fluid-structure interactions are commonly observed phenomena in industries as well as daily life ranging from small-scale droplet interactions to large-scale ocean wave-current interaction with offshore marine structures. These applications involve complex multiscale and coupled nonlinear dynamics which can be quite challenging to predict...

Fins or fairings are typically streamlined structures employed to reduce the vortex-induced unsteady forces acting on a bluff body by preventing shear layer roll-up in the near-wake region. In this work, fins would refer to thin plate-like structures attached tangentially to the bluff body's top and bottom surfaces. Of particular interest here are...

An elastic foil interacting with a uniform flow with its trailing edge clamped, also known as the inverted foil, exhibits a wide range of complex self-induced flapping regimes such as large amplitude flapping (LAF), deformed and flipped flapping. In particular, the LAF is of interest for its applications in the development of energy harvesting devi...

Two side-by-side elastic foils placed in an axial flow with the leading edges clamped lose their stability to exhibit in-phase or out-of-phase modes due to the proximity induced effects. Of particular, the passive out-of-phase flapping mode typically represents the clapping mechanism exhibited by biological organisms such as jellyfish and squid for...

Precise position and motion control of offshore vessels is often challenging, especially in harsh environment due to highly nonlinear dynamic loads from free-surface ocean waves and currents. In addition, coupled nonlinear effects of risers and mooring cables connected to the vessel can lead to unexpected responses, thus justifying the significance...

This paper is concerned with the partitioned iterative formulation to simulate the fluid-structure interaction of a nonlinear multibody system in an incompressible turbulent flow. The proposed formulation relies on a three-dimensional (3D) incompressible turbulent flow solver, a nonlinear monolithic elastic structural solver for constrained flexibl...

An elastic foil interacting with a uniform flow with its trailing edge clamped, also known as the inverted foil, exhibits a wide range of complex self-induced flapping regimes such as large amplitude flapping (LAF), deformed and flipped flapping. Here, we perform three-dimensional numerical experiments to examine the role of vortex shedding and the...

Due to the complexity involved in the vortex-induced vibration (VIV) of long offshore risers, the fundamental understanding of the coupled kinematics and dynamics of the standing and traveling waves is not well established. In the present contribution, a systematic numerical study on slender flexible riser immersed in a turbulent flow is performed...

We present a numerical study on vortex-induced vibration (VIV) of a freely vibrating two degree-of-freedom circular cylinder in close proximity to a stationary plane wall. Fully implicit combined field scheme based on Petrov-Galerkin formulation has been employed to analyze the nonlinear effects of wall proximity on the vibrational amplitudes and h...

We present a numerical study on the self-induced flapping dynamics of an inverted flexible foil in a uniform flow. A high-order coupled fluid-structure solver based on fully coupled Navier-Stokes and nonlinear structural dynamic equations has been employed. Unlike a conventional flexible foil flapping where the leading edge is clamped, the inverted...

This paper presents a numerical study on the self-induced flapping dynamics of an inverted flexible foil in the context of energy harvesting using piezoelectric elements. The inverted foil considered in this study is clamped at the trailing edge and the leading edge is free to oscillate. To simulate the nonlinear flapping dynamics of an inverted fl...

We present a fully implicit combined field scheme based on Petrov–Galerkin formulation for fluid–body interaction problems. The motion of the fluid domain is accounted by an arbitrary Lagrangian–Eulerian (ALE) strategy. The combined field scheme is more efficient than conventional monolithic schemes as it decouples the computation of ALE mesh posit...

A new high-order finite element Coupled Field with Explicit Interface (CFEI) code has been developed for simulating flapping motion of a thin flexible body in a uniform flow with strong add-mass effects. In the first part, we study the flapping dynamics of a single cantilevered plate for wide range of mass ratios and maintaining relatively low bend...

This work presents a review and theoretical study of the added-mass and aeroelastic instability exhibited by a linear elastic plate immersed in a mean flow. We first present a combined added-mass result for the model problem with a mean incompressible and compressible flow interacting with an elastic plate. Using the Euler-Bernoulli model for the p...