About

Professor Aditya Khair is a faculty member in the Department of Chemical Engineering at Carnegie Mellon University. He holds a Master of Engineering in Chemical Engineering from Imperial College London, a CAS Mathematics qualification from the University of Cambridge, and a PhD in Chemical Engineering from the California Institute of Technology. His educational background spans prestigious institutions, emphasizing a strong foundation in chemical engineering and mathematics. The information provided does not include specific details about his research focus or key contributions.

Research topics

• Materials science
• Nanotechnology
• Chemistry
• Chemical physics
• Physics
• Chromatography
• Engineering
• Chemical engineering
• Thermodynamics
• Physical chemistry
• Mathematics
• Optoelectronics
• Organic chemistry
• Quantum mechanics

Selected publications

• Nonantiperiodic Nonlinear Electrophoresis of Colloidal Particles

  Analytical Chemistry · 2025-11-05

  articleCorresponding

  Presented here is the first synergistic experimental observation and computational prediction of nonantiperiodic nonlinear electrophoresis (NANEP), obtained by imposing a sinusoidal nonantiperiodic voltage on negatively charged colloidal (polystyrene) particles in a microfluidic device. The motion of micrometer-sized polystyrene particles driven by NANEP was experimentally observed and predicted computationally, demonstrating that a net particle drift can be obtained with the application of a (spatially uniform) AC signal without the need of a DC bias. Experiments applying AC voltages with amplitudes of 150 and 500 V while toggling on and off the nonantiperiodic signal were conducted, from which particle position was measured and compared with the predictions from simulations of the full nonlinear electrokinetic equations, obtaining good agreement in the amplitude of the particle position oscillation and its net drift. Further experiments varying the amplitude of the applied voltage signal were used to build a net drift speed profile as a function of the electric field peak-to-peak amplitude. The numerical simulations identified fore-aft spatial symmetry breaking in the period-averaged velocity profile and electric field around the particle as the mechanism for generating nonzero net particle drift.

  PublisherDOI

• Dynamic interfacial mechanics due to transiently adsorbing ionic surfactants

  Journal of Engineering Mathematics · 2025-11-10

  articleOpen accessSenior author

  Abstract An analysis of the transient adsorption of monovalent ionic surfactant to an initially clean, planar interface is performed. We invoke the thin-double-layer limit and solve for the surfactant interfacial concentration when the surfactant adsorbs according to Langmuir kinetics and the counterion does not. We analyze the early-time behavior and the approach to equilibrium of the system, deriving asymptotic approximations for the surfactant interfacial concentration, and the bulk ion concentration and electric potential dynamics. We extend our analysis to incorporate the effect of added monovalent, non-adsorbing electrolyte and find an analogous asymptotic expression for the surface concentration dynamics. We use these analyses to compute dynamic interfacial mechanics in two scenarios: (i) when ionic surfactant transiently adsorbs to an initially clean interface and (ii) when the equilibrated interface undergoes small-amplitude area oscillations. In case (i) the adsorption dynamics resemble kinetically limited adsorption with ambipolar diffusion in the bulk, and at early times the growth of the interfacial concentration of surfactant is linear in time. In case (ii) we show that the Langmuir desorption rate constant can be obtained by finding the frequency of oscillation at which $$\text {Re}(E/E_0) = \frac{1}{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mtext>Re</mml:mtext> <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>E</mml:mi> <mml:mo>/</mml:mo> <mml:msub> <mml:mi>E</mml:mi> <mml:mn>0</mml:mn> </mml:msub> <mml:mo>)</mml:mo> </mml:mrow> <mml:mo>=</mml:mo> <mml:mfrac> <mml:mn>1</mml:mn> <mml:mn>2</mml:mn> </mml:mfrac> </mml:mrow> </mml:math> , where E is the complex surface compression elastic modulus, $$E_0$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>E</mml:mi> <mml:mn>0</mml:mn> </mml:msub> </mml:math> is that for an insoluble surfactant, and Re denotes the real part.

  PublisherOA PDFDOI

• Multiscale Perturbation Methods for Dynamic/Programmable Catalysis

  Industrial & Engineering Chemistry Research · 2025-10-31

  articleOpen accessSenior authorCorresponding
  PublisherDOI

• Double-layer structure and interfacial tension at an ionic surfactant-laden interface

  Journal of Colloid and Interface Science · 2025-05-22 · 2 citations

  articleOpen accessSenior author

  HYPOTHESIS: The electrical double-layer structure at an ionic surfactant-laden interface is unique due to the nonlinear coupling of interfacial charging and adsorption kinetics. Consequently, the interfacial equation of state is nonideal even at low surfactant concentrations. ANALYSIS AND COMPUTATIONS: ) is much smaller than the surfactant depletion length (h), i.e. ε=1/(κh)≪1. The asymptotic analysis is verified against numerical computations. FINDINGS: ). This asymptotic prediction is in qualitative agreement with experimental data. Our elucidation of this unique double-layer structure could provide new approaches to analyze dynamic interfacial tension, dilatational surface rheology and emulsion stability.

  PublisherDOI

• Hydrodynamic memory and Quincke rotation

  ArXiv.org · 2025-03-05

  preprintOpen access

  The spontaneous (so-called Quincke) rotation of an uncharged, solid, dielectric, spherical particle under a steady electric field is analyzed, accounting for the inertia of the particle and the transient fluid inertia, or ``hydrodynamic memory,'' due to the unsteady Stokes flow around the particle. The dynamics of the particle are encapsulated in three coupled nonlinear integro-differential equations for the evolution of the angular velocity of the particle, and the components of the induced dipole of the particle that are parallel and transverse to the applied field. These equations represent a generalization of the celebrated Lorenz system. A numerical solution of these `modified Lorenz equations' (MLE) shows that hydrodynamic memory leads to an increase in the threshold field strength for chaotic particle rotation, which is in qualitative agreement with experimental observations. Furthermore, hydrodynamic memory leads to an increase in the range of field strengths where multi-stability between steady and chaotic rotation occurs. At large field strengths, chaos ceases and the particle is predicted to execute periodic rotational motion.

  PublisherOA PDFDOI

• Hydrodynamic memory and Quincke rotation

  Physical Review Fluids · 2025-09-18 · 1 citations

  article
  PublisherDOI

• Marangoni Instability Driven by Adsorption and Association of Oppositely Charged Surfactants at an Oil–Water Interface

  Industrial & Engineering Chemistry Research · 2025-07-18

  articleOpen access

  When an aqueous buffer solution of the cationic surfactant tetradecyltrimethylammonium bromide near neutral pH is contacted with a solution of the fatty acid surfactant palmitic acid in tetradecane, convective flows appear spontaneously at the interface. This coincides with turbidity formation in the aqueous phase, consistent with aggregation between the headgroups of the two surfactants. Motivated by these experimental observations, a mathematical model is developed for transport, adsorption, and fluid flow in two immiscible contacting fluid phases, each containing a distinct surfactant. Linear stability analysis reveals that gradients generated by dynamic adsorption alone cannot drive instability, which only becomes possible if there is a process by which adsorbed surfactant is removed from the interface, as modeled by an interfacial reaction representing formation and desorption of aggregates in the experiments. A full numerical simulation shows that asymmetry in surfactant transport properties can inhibit convection due to the accumulation of surfactants on the interface.

  PublisherDOI

• A phenomenological model for chains and bands in dipolar suspensions

  Journal of Rheology · 2024-06-04 · 5 citations

  articleSenior author

  We introduce a phenomenological model for the dipolar interaction of polarizable particles under an external field, where the relative radial and rotational components of a particle pair interaction can be tuned. We show that the relative strengths of these two components govern the microstructure and dynamics of a suspension of such particles. Notably, dominant radial interactions give rise to the formation of zigzag band patterns, which were previously only thought to occur in systems where hydrodynamic interactions dominate. Through this phenomenological model, we show that dipolar interactions can be used to access an array of patterns in suspensions of polarizable particles, from chains to bands, which would dramatically affect suspension shear rheology, for instance.

  PublisherDOI

• The influence of active agent motility on SIRS epidemiological dynamics

  arXiv (Cornell University) · 2024-06-04

  preprintOpen accessSenior author

  Active Brownian disks moving in two dimensions that exchange information about their internal state stochastically are chosen to model epidemic spread in a self-propelled population of agents under the susceptible-infected-recovered-susceptible (SIRS) framework. The state of infection of an agent, or disk, governs its self-propulsion speed; consequently, the activity of the agents in the system varies in time. Two different protocols (one-to-one and one-to-many) are considered for the transmission of disease from the infected to susceptible populations. The effectiveness of the two protocols are practically identical at high values of the infection transmission rate. The one-to-many protocol, however, outperforms the one-to-one protocol at lower values of the infection transmission rate. Salient features of the macroscopic SIRS model are revisited, and compared to predictions from the agent-based model. Lastly, the motility induced phase separation in a population of such agents with a fluctuating fraction of active disks is found to be well-described by theories governing phase separation in a mixture of active and passive particles with a constant fraction of passive disks.

  PublisherOA PDFDOI

• Spontaneous locomotion of a symmetric squirmer

  Journal of Fluid Mechanics · 2024-03-18 · 4 citations

  articleOpen access

  The squirmer is a popular model to analyse the fluid mechanics of a self-propelled object, such as a micro-organism. We demonstrate that some fore–aft symmetric squirmers can spontaneously self-propel above a critical Reynolds number. Specifically, we numerically study the effects of inertia on spherical squirmers characterised by an axially and fore–aft symmetric ‘quadrupolar’ distribution of surface-slip velocity; under creeping-flow conditions, such squirmers generate a pure stresslet flow, the stresslet sign classifying the squirmer as either a ‘pusher’ or ‘puller’. Assuming axial symmetry, and over the examined range of the Reynolds number $Re$ (defined based upon the magnitude of the quadrupolar squirming), we find that spontaneous symmetry breaking occurs in the puller case above $Re \approx 14.3$ , with steady swimming emerging from that threshold consistently with a supercritical pitchfork bifurcation and with the swimming speed growing monotonically with $Re$ .

  PublisherOA PDFDOI

Recent grants

• Nonlinear Electrophoresis of Charged Colloidal Particles

  NSF · $299k · 2020–2023

• CAREER: Electrokinetic Flows and Electrochemical Dynamics in Concentrated Electrolytes and Ionic Liquids

  NSF · $400k · 2014–2019

• Coupling Electrokinetics and Rheology: Novel Flows, Interactions and Particle Motions

  NSF · $340k · 2011–2015

Frequent coauthors

• Lynn M. Walker

  University of Minnesota

  20 shared

• Lauren D. Zarzar

  Pennsylvania State University

  13 shared

• R. Kailasham

  Carnegie Mellon University

  12 shared

• Stephen Garoff

  Carnegie Mellon University

  11 shared

• Robert D. Tilton

  Carnegie Mellon University

  10 shared

• Aref Hashemi

  University of Notre Dame

  9 shared

• Todd M. Squires

  University of California, Santa Barbara

  9 shared

• John F. Brady

  California Institute of Technology

  7 shared

Education

• M.S., Chemical Engineering

  Imperial College London

  2001

• Other, Mathematics

  University of Cambridge

  2002

• Ph.D., Chemical Engineering

  California Institute of Technology

  2007

Awards & honors

• Metzner Early Career Award from the Society of Rheology
• Camille Dreyfus Teacher-Scholar Award
• NSF CAREER Award
• Charles Kaufmann Foundation New Investigator Research Grant
• Frenkiel Award of the APS Division of Fluid Dynamics