arXiv subjects

Harinadha Gidituri

Publications and source records attributed to Harinadha Gidituri.

3 recordsLinked to original sources

arXiv2026

Microswimmers create bicontinuous emulsions in binary fluids

We consider a generic case of neutrally wetting microswimmers in symmetric mixtures of two phase separating fluids, using hydrodynamic simulations. The swimmers spontaneously emulsify the two fluids into bicontinuous foam-like state. The two principal activity components: source dipole (self-propulsion) and force dipole (active mixing), create a twofold mechanism to stabilise the structures. When the self-propulsion is too strong, the swimmers cross the interfaces rapidly and the two fluids will phase separate. Below this threshold, the active stresses from the force dipoles, stabilise a dynamic and bicontinuous foam-like state. When the activity is turned off, the system relaxes into a kinetically trapped bicontinuous state, with particles permanently trapped at the interfaces. Our results provide a microscopic route to tunable active emulsions, with implications for bacterial suspensions and synthetic active matter.

cond-mat.soft↗

arXiv2025

Interface crossing behavior of prolate microswimmers: thermo and hydrodynamics

Motivated by recent experiments of motile bacteria crossing liquid-liquid interfaces of isotropic- nematic coexistence (Cheon et al., Soft Matter 20: 7313-7320, 2024), we study the dynamics of prolate microswimmers traversing clean liquid-liquid interfaces. Using large-scale lattice Boltzmann simulations, we observe that neutrally wetting swimmers can be either trapped or cross the in- terface, depending on their initial angle, swimming speed and the interfacial tension between the two fluids. The simulation results are rationalized by considering a competition between interfacial (thermodynamic) and active (hydrodynamic) forces. The swimmers get trapped at the interface due to a thermodynamic trapping force, akin to Pickering effect, when the forces from interfacial tension dominate over the swimming forces. The trapping behavior can be captured by calculating a critical capillary number by balancing the interfacial and active energies. This prediction agrees remarkably well with the numerical simulations as well as the bacterial experiments of Cheon et al., (Soft Matter 20: 7313-7320, 2024). Finally, our results demonstrate that the torque resulting in a reorientation of the swimmers parallel to the interface have both hydro and thermodynamic components.

cond-mat.soft↗

arXiv2022

Reorientation dynamics of microswimmers at fluid-fluid interfaces

We study the orientational and translational dynamics of spherical microswimmers trapped at fluid interfaces, in terms of the force dipole and source dipole components of their flow field. Using numerical simulations and analytical calculations, we show that the force dipole exerts a torque, orienting pushers parallel to the interface, and pullers in normal direction. The source dipole results in particle rotation only for a finite viscosity contrast between the two fluids, in agreement with previous studies. The superposition of these two contributions leads to an rotational dynamics with a steady-state orientation that depends on the relative magnitudes of the force and source dipoles. In the general case, swimmers with weak force dipoles and strong pullers are observed to align perpendicular to the interface and become stationary, while strong pushers have a finite inclination angle towards the lower viscosity fluid and swim along the interface.

cond-mat.soft↗