Research Projects

The undulating motion of the hydrofoil simulates fish-like swimming. It has long been recognized that wing flexibility enhances force generation. However, there is only a limited understanding of the FSI aspect of the problem. The majority of the previous investigations were based on the time-averaged thrust generation, and comparatively less attention was given to understanding the mechanism of instantaneous hydrodynamic force generation owing to the undulating motion of the flexible wing/foil/panel despite the highly unsteady nature of the problem. We reported (Deshpande and Vishwasrao, JFM 2021) the dynamics of the instantaneous thrust generation and elastic deformation of the panel for the first time. We also demonstrated that the inception of a trailing-edge vortex (TEV) and instantaneous thrust generation occur at the same time. We revealed that the flexible panel undergoes a passive deformation during pitching due to fluid resistance and this passive deformation causes phase lag between the leading and trailing edge (LE and TE) of the pitching panel. It is important to understand the role of both phase lag and passive deformation in influencing the thrust generation characteristics independently. For that purpose, phase-lag between LE and TE can be imparted by introducing a torsional spring between the LE of the panel and the shaft having undulating motion. The effect of influence of phase-lag can be investigated for the rigid panel without undergoing passive elastic deformation. Moreover, controlling and/or manipulating the phase-lag and/or passive deformation as a function of the time can reveal many unknown intriguing facts about the unsteady hydrodynamics of flexible propulsor. The use of shape memory alloy (SMA) in the form of thin wires attached to the panel can make the flexural stiffness of the panel time dependent. Variation in flexural stiffness by alternate heating and cooling the SMA wire should influence the passive elastic deformation in an undulating cycle. To our knowledge, we shall be the first to investigate the influence of controlling the deformation using SMA in India. The variation in the velocity of TE during an undulating cycle is another important parameter to decide the thrust generation characteristics as it has got a direct relation with the strength of the vortex forming at the TE of the panel. Since a large number of parameters influence the propulsive performance, developing an artificial intelligence (AI) based machine learning algorithm to optimize the propulsive performance of a propulsor is needed. Furthermore, the possibility of building a digital twin based on the comprehensive instantaneous hydrodynamic force and moment data, elastic deformation data, and near-field velocity data needed be explored. The present proposal is based on the lead obtained from our findings from the previous project which was successfully accomplished under CRG scheme (2019/CRG/1445) during years 2020-2022.