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Life in Stokes flow: Liquid Crystal based microswimmers in confinement
Soft and Active Matter Group
Department of Mechanical Engineering, Indian Institute of Technology Hyderabad
Hyderabad, Telangana, India
July 2024 - Present
Squeezing through soft confinement
Lorem Ipsum
TBD
Smita S Sontakke†, Premkumar Iyer†, Ranabir Dey.
(† - Contributed equally)
(TBD)
Dynamics of Nematic Liquid Crystal Swimmers
Lorem Ipsum
TBD
Premkumar Iyer†, Ranabir Dey.
(TBD)
About liquid marbles: from impact to vibrations
Microfluidic Devices and Heterogenous Systems Lab
Centre for Nanoscience and Engineering, Indian Institute of Science
Bengaluru, Karnataka, India
May 2023 - April 2024
On the nature of shell encapsulation of LMOI
Is an ongoing project (To be updated soon)
Hydrophobic particle coating for enhanced droplet deposition
In this work, a thorough investigation of the impact dynamics of particle-laden droplets (liquid marbles) over various surfaces was conducted. The particle-laden droplets of various mass loading were prepared and impacted upon a hydrophobic surface. The impact dynamics and subsequent breakage of the droplet interface were recorded by means of a high-speed camera. Such breakages have a wide range of applications, such as printing, spray coating, pesticide/insecticide spraying, needle-less drug delivery, etc.
Hydrophobic particle coating for enhanced droplet deposition
Rutvik Lathia†, Premkumar Iyer†, Chandantaru Dey Modak, Prosenjit Sen.
(† - Contributed equally)
(Manuscript under review)
On multiphase flows and complex fluid systems
Department of Mechanical Engineering
National Institute of Technology Calicut
Kozhikode, Kerala, India
August 2022 - July 2024
On the behaviour of coated droplets undergoing freezing
This is the outcome of the master's thesis work and has been carried out with the collaboration of Prof. Prosenjit Sen, PI of MDHS Lab, CeNSE, IISc and Prof. Sumer Dirbude, Department of Mechanical Engineering, NIT-C.
We conducted carefully controlled experiments to understand the freezing transitions to understand the influence the shell encapsulated droplet system imparts in a sessile configuration. Via statistically meaningful experiments, the kinetics-driven freezing process of recalescence (stage one freezing) and main solidification (stage two freezing) process has been explored, while drawing contrast to the sessile oil-coated droplets (on oil-infused surface). The observations are drawn from high-speed imaging supported by IR based thermographic imaging. With conjunction of the classical nucleation theory an attempt has been made to model the phenomenon and account for the enhanced interfacial chemistry of the shell encapsulation. This model aids in understanding the anomalous behaviour observed owing to the speeding up of the nucleation kinetics. Overall, the experiments and modelling have enabled uncovering the insights of recalescent freezing in complex fluid system like LMOI and the effects imparted by such particulate shell encapsulation.
On the behaviour of sessile coated droplets undergoing freezing
Premkumar Iyer. Rutvik Lathia, Sumer Dirbude, Prosenjit Sen.
(Manuscript under review)
Numerical investigation of damped vibrations in slender flexible structures
In this work, an immersed boundary method-based IB2d code is used for the estimation of drag or damping coefficients for vertical flexible structures. Flexible structures interacting with the viscous incompressible fluid are encountered in the study of fish swimming, underwater cables, transmission cables, flapping wings, sensors or resonators, etc. Estimation of drag or damping coefficient is important for the efficient design of devices where vibration-induced motions are involved. While studying vibration-induced vortex, a flexible beam can be modelled as having a wobbly motion and its damping in the viscous fluid can be studied. The slender flexible vertical beam of fixed length is subject to the sinusoidal-wobbly mode shapes. Under various mode shapes, the temporal evolution of the nondimensional damping force is obtained. The results exhibited an expected exponential decay in the drag force acting over the beam. It is concluded that the damping coefficient obtained is seen to reduce with an increase in amplitude with certain exceptions.
Numerical investigation of damped vibrations in slender flexible structures
Sumer Dirbude, Premkumar Iyer.
Advances in Manufacturing and Materials. FLUTE 2023. Lecture Notes in Mechanical Engineering. Springer, Singapore.
https://doi.org/10.1007/978-981-97-3173-2_4
Effect of combustor geometry on combustion characteristics of pre-mixed hydrogen-air mixture in a micro-combustor
The work addresses the challenges associated with the inclusion of bluff bodies as a flame anchorage in micro-combustors. The designs are inspired from common observation and are anticipated to serve the purpose of the work being proposed. The study involves a two-dimensional computational domain obtained by undertaking considerable assumptions. An investigation on the effect of the geometry used on the flow field and flame structure of a micro-combustor supplied with premixed lean hydrogen and air mixture is done. The results depicted that the flame anchorage is offered by the corner recirculation zone which aided in placing the flame root in the neck of combustor body. In the case of multi-chambered micro-combustor, the inserted ribs behave like an orifice and the vena contracta is responsible for creating an environment where exhaust gas recirculation is evident, leading to a boosted preheating and stabilized flame.
The multiphase flows and drift flux model: The case of two-phase flow through a pipe
The slip law, introduced by Zuber and Findlay, is an important part of the drift flux model, which is used to model the behaviour of two-phase flows. The effects of changes in slip velocity due to pipe diameter are examined to predict behaviour in different geometries and develop an understanding of the underlying physics. The simulation results showed that a sharp peak was observed when liquid and gas were injected at the inlet due to the acceleration terms responsible for the pressure pulses, but the peak vanished after a short while and the pressure development afterwards was mainly due to friction forces. This study presents a comparative analysis of the approximations for fluid properties at cell faces in a two-phase flow model using the first and second-order upwind scheme. A larger diameter causes rapid fluctuations and pressure pulses, resulting in increased gas mass flow rates and gas phase velocities. The increased gas void fraction leads to increased slip between phases, exacerbating the gas void fraction. The second-order scheme closely follows flow trends, but there is no significant improvement over the first-order scheme for the problem under consideration.
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