Sukalyan Bhattacharya

• Texas Tech University

This article describes the flow-induced axial dispersion of solutes in conduits of arbitrary cross-sections when the channel wall affects the process due to either adsorption or surface-reaction. The analysis uses a multiple time-scale technique to identify three transport coefficients which characterize the interplays between convection, diffusion...

This article reveals how apparently similar looking nano-particles with same size, shape and mass may exhibit widely varying Brownian diffusivity due to inherent features of nano-scale dynamics. Such variabilities may, in certain cases, reach order of magnitude fluctuations depending on the interfacial and bulk properties of the Brownian body. Acco...

This paper presents an analytical and computational method to describe natural frequencies of a spherical bubble residing near a solid sphere of an arbitrary size in an otherwise unbounded fluid. Under low capillary and Reynolds number limits, the relevant hydrodynamic fields are converted into time-invariant but frequency-dependent quantities by t...

This article elucidates how unsteady hydrodynamic interactions between two closely situated spheres in a viscous liquid affect their time-dependent motion. The system represents typical Brownian particles for which temporal inertia is always comparable to the viscous forces even though convective inertia is negligible. The analysis quantifies the t...

This article presents a novel algorithm to predict the shape and the support configurations of a magnetic robot acting like a supple beam which deforms due to an imposed magnetic field. The soft magnet loosely rests on a flat horizontal surface which provides the pivoting supports to the robot to attain its deformed shape. The key difficulty in ana...

This paper describes the solution of a vector function around disconnected spheres where the fields are governed by a hybrid between Stokes and Helmholtz equations. The governing relation known as Brinkman equation typically appears to represent the spatial variations in Darcy's flow in porous medium as well as in unsteady Stokesian hydrodynamics....

This article explains how a charged body can retain its integrity despite electrostatic repulsion within itself. The study requires derivation of the field equations governing the velocity of any arbitrary element within the system. These relations are obtained from two Lagrangian principles based on obvious and least disruptive modifications of kn...

This article describes how a drop with an embedded particle exhibits interfacial waves with transient decay due to the interplay between capillary and viscous effects. To reveal the damped oscillation of the system properly, the deformation and pressure fields inside the domain are described in terms of complete sets of basis functions. Such repres...

This paper uses eigenexpansion technique to describe electro-osmotic effect on unsteady intrusion of a viscous liquid driven by capillary action in a narrow channel. It shows how the dynamics can be manipulated by imposing an electric field along the flow direction in the presence of free charges. Similar manipulation can generate controlled transi...

This article describes an unexplored transport phenomenon where a mildly viscoelastic medium encroaches a narrow capillary channel under the action of surface-tension force. The ultimate goal of the study is to provide the penetration length and the intrusion rate of the liquid as functions of time. The resulting analysis would be instrumental in b...

This article describes unexplored details of the intriguing spectral manifestation of the small-amplitude waves at the surfaces of a bubble-laden drop. Its natural frequencies of interfacial pulsation reveal a non-trivial variation with the position of the cavity inside the liquid. This configurational dependence of spectra is calculated for arbitr...

This article addresses a classical fluid mechanics problem where the effect of capillary action on a column of viscous liquid is analyzed by quantifying its time-dependent penetrated length in a narrow channel. Despite several past studies, a rigorous mathematical formulation of this inherently unsteady process is still unavailable, because these e...

Combusting metals burn at high temperatures and emit high-intensity radiation in the visible spectrum, which can oversaturate regular imaging sensors and obscure the field of view. Filtering the luminescence can result in limited information and hinder thorough combustion characterization. A method for “seeing through the flames” of a highly lumine...

This article discusses how to derive a closed-form analytical solution describing the profile of unidirectional flow through a class of noncircular tubes. The cross sections of the conduits are a slightly distorted version of regular shapes, like triangles or trapeziums or rectangles, that are commonly seen in microfluidic or heat pipe applications...

This article describes how an embedded bubble changes the surface wave of a suspended liquid drop, and how such modifications, if recorded experimentally, can be used to detect voids in typically opaque interior of the fluid. The analysis uses a matrix formalism to predict the frequencies for natural oscillation and the deformation for acoustically...

In this paper, a novel numerical technique is generalized for analysis of mutual flow interactions between unequal particles in cylinder-bound pressure-driven flow of highly viscous fluid. The methodology is general enough to account for any polydisperse many-sphere system confined in a circular channel. The scheme is especially useful for the geom...

This article presents a new method to describe creeping motion of two-particle system in quiescent fluid confined in a conduit. The analysis is specifically focused on two spheres in cylinder-bound viscous fluid where both interparticle and particle–wall flow interactions are significant. We quantify these interactions by the spatial variation of f...

This article describes the radial drift of a suspended sphere in a cylinder-bound Poiseuille flow where the Reynolds number is small but finite. Unlike past studies, it considers a circular narrow conduit whose cross-sectional diameter is only \$1. 5\$–\$6\$ times the particle diameter. Thus, the analysis quantifies the effect of fluid inertia on t...

The combined effects of radial drift due to flow inertia and diffusion due to Brownian motion significantly modify the radial probability distribution and the axial dispersion of conduit-bound suspended bodies. This interplay depends on the product of Peclet Pe and Reynolds Re numbers so that even apparently non-Brownian systems with high Pe exhibi...

The stochastic dynamics of a Brownian particle in a viscoelastic (VE) medium is an important phenomenon from micro-rheological perspective. In micro-rheology, the main question is how to predict the rheological properties by observing the Brownian motion in the it without using a rheometer, as the sample is too precious to be structurally destroyed...

The presence of a particle with specified velocity inside a cylindrical channel affects the pressure-field along the length of the conduit. In this article, we quantify this effect by using a new general method, which describes hydrodynamic interactions between a cylindrical confinement and a spherical particle under creeping flow assumption. The g...

Several past attempts were made to describe the penetration length in microchannels as a function of time for electroosmotic or capillary flow. In all of these studies, a complex governing equation is derived by taking into account the inertial contributions along with other forces. The system being unsteady, this derivation requires the considerat...

In simulations of creeping flow, the effect of suspended particles on a fluid is often represented by force singularities responsible for singular Stokesian solutions, which are infinite at the sphere center and decay far from the particle. In this article, we consider such singular fields centered at a point inside a cylindrical or annular conduit...

In this article, we discuss the effect of the bounding cylinder on the rheology of a dilute suspension. We consider a colloidal solution of spherical particles flowing through a cylinder under creeping motion assumption. For transport of such particulate fluid, the increase in the viscous loss due to the existence of suspended particles can be desc...

In this paper, we develop an efficient procedure to solve for the Stokesian fields around a spherical particle in viscous fluid bounded by a cylindrical confinement. We use our method to comprehensively simulate the general creeping flow involving the particle-conduit system. The calculations are based on the expansion of a vector field in terms of...

Hydrodynamic interactions between a confining boundary and a suspended or deposited particle affect the dynamics of a number of colloidal systems. For example, a fixed particle deposited on the wall of a cylindrical conduit enhances the flow-resistance in the channel by inducing additional pressure-drop. Similarly, required pressure-gradient to dri...

Creeping motion of multi-particle systems inside a cylindrical channel is an important phenomenon which affects many processes like blood-flow in bio-conduit or transportation in microfluid channels. Such systems involve both interparticle and particle-wall interactions which so far have not been fully analyzed when the size of the confining condui...

In this project, we have formulated an alternative boundary-layer theory. This new analysis will be able to mathematically describe flow-separation unlike the classical theory. In our research, we have partially validated the developed theory and concluded that approach has considerable potential to account for flow-separation. The effective descri...

Experimental evidence shows that suspended particles preferentially migrate away from confining boundaries due to the effect of a shear flow. In this paper, we consider an asymmetric particle in Poiseuille flow and determine an inertial lift force which can contribute to the particle migration. Under the influence of Poiseuille flow in a slit pore,...

We consider the hydrodynamic effect of small particles on the dynamics of a much larger particle moving normal to a planar wall in a highly bidisperse dilute colloidal suspension of spheres. The gap h(0) between the large particle and the wall is assumed to be comparable to the diameter 2a of the smaller particles so there is a length-scale separat...

In this article, we analyze the collective motion of a two-dimensional periodic array of spheres in a slit-pore confined by two parallel planar walls. We determine the friction coefficient of the spheres when all particles move with the same velocity along a particular direction and cooperate with each other in their motion. In order to solve this...

We consider the hydrodynamic effect of small particles on the dynamics of a much larger particle moving normal to a planar wall in a highly bidisperse dilute colloidal suspension of spheres. The gap $h_0$ between the large particle and the wall is assumed to be comparable to the diameter $2a$ of the smaller particles so there is a length-scale sepa...

Vortical flows with an axial (z-axis) swirl and a toroidal circulation (in the (rho,z)-plane) can be observed in a wide range of fluid mechanical phenomena such as flow around rotary machines or natural vortices like tornadoes and hurricanes. In this paper, we obtain exact analytical solutions for a general class of steady systems with such three-d...

Vortical flows with an axial swirl and a toroidal circulation can be observed in a wide range of fluid mechanical phenomena such as flow around rotary machines or natural vortices like tornadoes and hurricanes. These flows can be described by a general scalar equation if incompressible fluid and negligible viscous dissipation are assumed. We consid...

Hydrodynamic interactions of spherical particles in incident Poiseuille flow in a channel with infinite planar walls are investigated. The particles are suspended in a Newtonian fluid, and creeping-flow conditions are assumed. We consider the motion of freely suspended particles as well as the forces and torques acting on particles adsorbed at a wa...

Hydrodynamic interactions in a suspension of spherical particles confined between two parallel planar walls are studied under creeping-flow conditions. The many-particle friction matrix in this system is evaluated using our novel numerical algorithm based on transformations between Cartesian and spherical representations of Stokes flow. The cartesi...

Owing to the inertial effect of the flow, an unsteady hydrodynamic force will act on a particle of arbitrary shape undergoing a steady rigid-body motion with small but finite Reynolds number if the axis of rotation of the particle is not its axis of rotational symmetry. Unsteady flow field is generated owing to such rotation of the body and as a re...

We study hydrodynamic interactions of spherical particles in incident Poiseuille flow in a channel with infinite planar walls. The particles are suspended in a Newtonian fluid, and creeping-flow conditions are assumed. Numerical results, obtained using our highly accurate Cartesian-representation algorithm [Physica A xxx, {\bf xx}, 2005], are prese...

This paper describes the results of our theoretical and numerical studies of hydrodynamic interactions in a suspension of spherical particles confined between two parallel planar walls, under creeping-flow conditions. We propose a novel algorithm for accurate evaluation of the many-particle friction matrix in this system--no such algorithm has been...

A complete analysis is presented for the far-field creeping flow produced by a multipolar force distribution in a fluid confined between two parallel planar walls. We show that at distances larger than several wall separations the flow field assumes the Hele–Shaw form, i.e. it is parallel to the walls and varies quadratically in the transverse dire...

A complete analysis is presented for the far-field creeping flow produced by a multipolar force distribution in a fluid confined between two parallel planar walls. We show that at distances larger than several wall separations the flow field assumes the Hele-Shaw form, i.e., it is parallel to the walls and varies quadratically in the transverse dir...

Small particles (or macromolecules) added to a colloidal solution of much larger species produce the effective structural force acting between the large particles and the walls. When the large particles are moving, the macromolecules can also produce non-equilibrium effects, which include the hydrodynamic and Brownian resistance forces. Our talk wi...

Without abstract

Without abstract

Using a recently developed image representation for Stokes flow in a half-space bounded by a planar wall Cichocki and Jones, Physica A 258, 273 1998, the image system is constructed for the flow field produced by a force multipole in the space bounded by two parallel walls. The image singularities are expressed in terms of products of double-reflec...

The Transport Element Method (TEM), is a Lagrangian methodology introduced in the recent past for the simulation of scalar transport in vortical flows. In the TEM the scalar field is solved in terms of the scalar gradient, the transport equation of which is substantially simplified using flow kinematics. The equations and simplifications considered...

The Transport Element Method (TEM), is a Lagrangian numerical methodology that has recently been introduced as an extension of the Vortex Element Method (VEM) for the simulation of vortex flows in which scalar fields are present. In the TEM the scalar field is solved in terms of the scalar gradient the Lagrangian transport equation of which is subs...

Thesis (M.S.)--University of Connecticut, 2000. Includes bibliographical references.