arXiv subjects

KVS Chaithanya

Publications and source records attributed to KVS Chaithanya.

5 recordsLinked to original sources

arXiv2026

Effects of Porous Media Properties and Flow Environment on Drug Release from Porous Implants

Drug-Filled Porous Implants (DFPIs) are an innovative solution for delivering drugs in a controlled and sustained manner to target sites. To optimize their performance across various physiological conditions, it is essential to understand how fluid flow and porous media properties influence the drug release process. In this work, we numerically investigate a wide range of flow conditions and their effects on drug release from DFPI. The DFPI is modeled as a homogeneous, saturated porous medium, with flow through the porous structure modeled using the Forchheimer-extended Darcy law. Drug diffusion within the DFPI and its transport through the surrounding channel are simulated using a diluted species transport approach. The results reveal the impact of flow conditions and porous media characteristics on the drug release profile of the implant and drug availability within the channel. The variations in drug release behavior are analyzed by modeling the release as an apparent first-order process with a time-dependent rate constant. Notably, the results highlight specific conditions under which the rate constant increases during the later stages of drug release from the DFPI, particularly at high Reynolds numbers, while also ensuring a prolonged operational time period of the implant. These findings suggest the potential for developing intelligent DFPI designs capable of delivering drugs in a manner more attuned to the specific needs of the application.

physics.chem-ph↗

arXiv2026

Nonlocal flow sampling enables vortex trapping of heavy particles

Most analyses of inertial particle motion in vortical flows rely on the point-particle approximation, in which the fluid velocity is assumed to be linear at the scale of the particle, and for heavy particles inertia typically leads to centrifugal expulsion from vortex cores. Here, we show that a spatially extended particle, modeled as a rigid symmetric dumbbell of two identical inertial point particles connected by a massless rod that samples the flow at two points, can converge to a vortex-centered spinning state. We study the dynamics of this inertial dumbbell in a steady two-dimensional Lamb-Oseen vortex and identify three qualitatively distinct long-time behaviors controlled by the Stokes number. In the weak-inertia limit, the motion remains bounded and traces spirographic-like trajectories around the vortex center, while at sufficiently large inertia centrifugal effects dominate and trajectories spiral outward, approaching inertial point-particle behavior. Between these limits, the dumbbell can reach a trapped spinning state in which the center-of-mass converges to the vortex center and spins steadily, with accessibility determined by the initial conditions. Basin-of-attraction maps and ensemble statistics reveal a non-monotonic dependence of the accessibility of the spinning state on inertia, with basins of finite measure occurring only over an intermediate range of Stokes numbers. Linear stability is governed by the logarithmic slope of the vortex angular-velocity profile, and for the Lamb-Oseen vortex the spinning state is stable for all Stokes numbers. These results highlight how nonlocal flow sampling by spatially extended inertial particles can fundamentally alter transport and long-time behavior in vortical flows.

physics.flu-dyn↗

arXiv2025

Viscoelastic Effects on the Hydrodynamics of an Active Compound Particle

Understanding the hydrodynamics of microswimmers in viscoelastic fluids and confined environments is crucial for interpreting their behaviour in natural settings and designing synthetic microswimmers for practical applications like cargo transport. In this study, we explore the hydrodynamics of a concentric active compound particle - a model microswimmer (a squirmer) positioned at the centre of a viscoelastic fluid droplet (a model cargo) suspended in another viscoelastic medium. We consider the Oldroyd-B constitutive model to characterize the fluids and employ a perturbative approach in the Deborah number to analyze viscoelastic effects analytically, assuming a small Capillary number so that the droplet remains spherical and does not deform. We examine three cases: (i) a squirmer confined within a viscoelastic fluid droplet suspended in a Newtonian fluid, (ii) a squirmer confined within a Newtonian fluid droplet suspended in a viscoelastic fluid, and (iii) a squirmer confined within a viscoelastic fluid droplet suspended in another viscoelastic fluid. Our findings reveal that the swimming speeds of the squirmer and the droplet are determined by the complex interplay of viscoelasticity, the size ratio of the droplet to the squirmer (confinement strength), and the viscosity ratio of the surrounding fluid to the droplet fluid. A critical aspect of this interaction is the positioning of stagnation points within the fluid flow, which governs the distribution of polymeric stress. This distribution, in turn, plays a crucial role in determining the influence of viscoelasticity on the squirmer's dynamics. Our analysis suggests that viscoelastic effects can either enhance or hinder the swimming speed of the squirmer when confined in a droplet, depending on the specific configuration of the system.

physics.flu-dyn↗

arXiv2025

Cell-level modelling of homeostasis in confined epithelial monolayers

Tissue homeostasis, the biological process of maintaining a steady state in tissue via control of cell proliferation, death, and metabolic function, is essential for the development, growth, maintenance, and proper function of living organisms. Disruptions to this process can lead to serious diseases and even death. In this study, we use the vertex model for the cell-level description of tissue mechanics to investigate the impact of the tissue microenvironment and local mechanical properties of cells on homeostasis in confined epithelial tissues. We find a dynamic steady state, where the balance between cell divisions and removals sustains homeostasis. By characterising homeostasis in terms of cell count, tissue area, and the cells' neighbour count distribution, we identify the factors that govern regulated and ordered tissue growth. This work, therefore, sheds light on the mechanisms underlying tissue homeostasis and highlights the importance of mechanics in the control of biological processes such as tissue development and disease pathology.

physics.bio-ph↗

arXiv2024

Transport of topological defects in a biphasic mixture of active and passive nematic fluids

Collectively moving cellular systems often contain a proportion of dead cells or non-motile genotypes. When mixed, nematically aligning motile and non-motile agents are known to segregate spontaneously. However, the role that topological defects and active stresses play in shaping the distribution of the two phases remains unresolved. In this study, we investigate the behaviour of a two-dimensional binary mixture of active and passive nematic fluids to understand how topological defects are transported between the two phases and, ultimately, how this leads to the segregation of topological charges. When the activity of the motile phase is large, and the tension at the interface of motile and non-motile phases is weak, we find that the active phase tends to accumulate $+1/2$ defects and expel $-1/2$ defects so that the motile phase develops a net positive charge. Conversely, when the activity of the motile phase is comparatively small and interfacial tension is strong, the opposite occurs so that the active phase develops a net negative charge. We then use these simulations to develop a physical intuition of the underlying processes that drive the charge segregation. Lastly, we quantify the sensitivity of this process on the other model parameters, by exploring the effect that anchoring strength, orientational elasticity, friction, and volume fraction of the motile phase have on topological charge segregation. As $+1/2$ and $-1/2$ defects have very different effects on interface morphology and fluid transport, this study offers new insights into the spontaneous pattern formation that occurs when motile and non-motile cells interact.

physics.bio-ph↗