Pushpendra Singh

Ph.D.; University of Minnesota-Twin Cities; Aerospace Engineering; 1991

M.S.; University of Minnesota-Twin Cities; Aerospace Engineering; 1989

B.Tech.; Indian Institute of Technology, Kharagpur; Aeronautical Engineering; 1985

B. Tech.; IIT Kanpur; Aeronautical Engineering; 1985

ME 490 - MECH ENGR PROJECT A

ME 726 - INDEPENDENT STUDY II

ME 792B - PRE-DOCTORAL RESEARCH

ME 701C - MASTER'S THESIS

ME 700B - MASTER'S PROJECT

ME 611 - DYNAM OF INCOMP FLUIDS

ME 701B - MASTER'S THESIS

ME 790A - DOC DISSERTATION & RES

ME 343 - MECHANICAL LABORATORY I

ME 725 - INDEPENDENT STUDY I

In my teaching, I have developed well thought-out lectures with examples and explanations to help NJIT students learn efficiently. I have developed and taught new courses thereby expanding the curriculum within the department such as ME-713 “Non-Newtonian Fluid Mechanics” and ME-717 “Computational Fluid Dynamics.” These courses represent current thought in the respective subjects and provide the NJIT graduates a competitive advantage in many companies located in the New York and New Jersey Metropolitan area.

My current research interests fall into the following three areas: the fluid dynamics of viscoelastic liquids, the direct numerical simulations of particulate multiphase fluids, electrohydrodynamic manipulation of particles, and the fluid dynamics of floating particles. My goal within the broad area of multiphase fluid mechanics is to develop novel theoretical and experimental methods for exploring interesting features of dynamics, from both applied and fundamental points of views. My group is actively involved in a range of research activities, such as theoretical (numerical) and experimental studies of microscale dynamics in particulate materials and liquids, and its role in determining the macro (continuum) scale properties; development of new efficient computational methods for viscoelastic particulate flows; large-scale computational investigations of viscoelastic flows in complex domains, e.g., injection molding, direct numerical simulations of drop deformation and breakup in polymer blends. In addition, I have been involved in the direct numerical simulations of porous media flows, experimental studies of the elctrorheological fluids, applications of dielectrophoresis for separating particulates and identifying biological cells, and several industrial research projects. a. Dynamics of floating particles We have developed a new numerical scheme for simulating the motion of particles trapped in two-fluid interfaces. The scheme uses the distributed Lagrange multiplier method to enforce the rigid body motion constraint and the level set method to track the interface. The particles are moved in a direct simulation respecting the fundamental equations of motion of fluids and solid particles without the use of models. This work fills a gap since there are no other theoretical methods available to describe the nonlinear fluid dynamics of capillary attraction. The code allows us to calculate the motion of particles under the constraints that the contact angle on smooth surfaces is fixed by the Young-Dupre law and on the sharp edges of particles the contact line is pinned so that the contact angle changes as the motion proceeds. We are currently using this code to study self assembly of submicron sized prismatic particles in interfaces. b. Dielectrophoresis of biological cells and particles A numerical scheme based on the distributed Lagrange multiplier method is used to study the motion of biological cells and particles, including nano sized particles, suspended in liquids. The dielectric constants of the liquid and particles are assumed to be different. Simulations show that in a uniform electric field the evolution of the particle scale structures depends on the ratio of electrostatic particle-particle interactions and Brownian forces. When this ratio is of O(100) or more, particles form stable chains and columns whereas when it is of O(10) the particle distribution is random. In a non-uniform electric field, when this ratio is smaller than O(10), Brownian forces do not influence the eventual collection of particles as well as the particular locations where particles are collected. However, Brownian motion influences the transient particle trajectories. We are currently working on developing techniques that will allow us to use dielectrophoretic forces for separating particles, distinguishing biological cells and modifying flow in micro scale devices. c. Direct numerical simulation of viscoelastic particulate flows We have developed a new efficient numerical scheme for viscoelastic particulate flows based on the distributed Lagrange multiplier/fictitious domain method. Using this scheme we have been able to simulate motion of thousands of particles suspended in a viscoelastic liquid. This capability is by-far unparalleled in particulate flow simulations. I have also used this numerical method to explain why a sphere sedimenting near a vertical wall in a viscoelastic moves towards the wall. This phenomenon remained unexplained for several years. d. Direct numerical simulation of viscoelastic two-phase flows We have developed a new numerical scheme for solving viscoelastic two-phase flow problems containing drops and bubbles. Developing efficient iterative solvers for viscoelastic flows has been a challenging problem because the configuration tensor, a positive-definite tensor, may become negative due to discretization errors, and an initial value problem with a negative configuration tensor is Hadamard unstable. To overcome this numerical problem, I developed an algorithm that guarantees the positive-definiteness of the configuration tensor. Using this method we have simulated (and explained) the formation of a two-dimensional cusp shaped trailing edge and a negative wake for a bubble rising in a viscoelastic liquid (as in experiments). Recently, we have been able to show that the Oldroyd-B model predicts a sudden increase in the rise velocity at a critical volume and that this sudden increase happens when the bubble forms a cusp shaped trailing edge, as observed in experiments. One of the goals of this work is to quantitatively compare the numerical predictions with the experimental data for the real complex fluids. To solve large industrial-scale problems, robust parallel numerical algorithms are being developed. e. Modeling and simulations of rolling and deformation of leukocytes adhering to walls The objective of this work is to experimentally investigate and develop models for describing the motion of a deformable leukocyte or cancer cell through a capillary or blood vessel. It is known that under certain physiological conditions (flow rate, etc.) the cell begins to adhere to the endothelium, and eventually rolls, deforms and extravasates through the endothelium. A model of cell deformation based on the embedded domain method in three dimensions is used to study this phenomenon. The model allows us to track the position of the cell membrane as well as the kinetics of bond formation between the cell membrane and endothelium. f. Modeling of complex fluids Material properties of complex fluids are primarily determined by the microstructure, i.e. the structure at the molecular or mesoscopic length scales, which can be easily modified by subjecting them to appropriate velocity gradient fields. For example, colloids, fluidized suspensions, polymeric liquids, and liquid crystalline fluids, etc. all have distinctive equilibrium microstructures that give rise to their respective macroscopic material properties. The objective is to use the direct numerical simulation data to quantify microscale dynamics and develop macroscale constitutive models for the evolution of microstructure in complex fluids. I have recently developed a novel technique for analyzing direct numerical simulation data, which my group is using for quantifying the microscale dynamics in fluidized suspensions and simple liquids. The constitutive models for micro- and macro-scale dynamics would provide a theoretical predictive capability that could be used for tailoring the microstructure by subjecting complex fluids to appropriate velocity gradient fields and thus obtain materials with desired mechanical properties.

Verma, S, & Benouaguef , I, & Singh, Pushpendra, & Musunuri, N, & Fischer, Ian S. (2023). Marangoni flow induced in a waterbody by the impact of a raindrop. Mechanics Research Communications, 133(104187), 104187 .

Benouaguef, Islam, & Musunuri, N, & Amah, E, & Blackmore, Denis L., & Fischer, Ian S., & Singh, Pushpendra (2021). Solutocapillary Marangoni flow induced in a waterbody by a solute source. Journal of Fluid Mechanics, Volume 922,

Amah, E., & Janjua, M., & Singh, Pushpendra (2018). Direct Numerical Simulation of particles in spatially varying electric fields. Fluids, 52(3),

Singh, Pushpendra, & Benouaguef, I. , & Musunuri, N., & Amah, E., & Blackmore, Denis L., & Fischer, Ian S. (2017). Flow induced on a salt waterbody due to the impingement of a freshwater drop or a water source. Mechanics Research Communications, 85, 89–95.

Musunuri, N., & Bunker, Daniel E., & Pell, S., & Fischer, Ian S., & Singh, Pushpendra (2017). Fluid Dynamics of Two-Dimensional Pollination in Ruppia . Procedia IUTAM, 20, 152-158 .

Marangoni flow induced in a waterbody by the impact of a raindrop
The 18th Northeast Complex Fluids and Soft Matter Workshop, January 2023. , January (1st Quarter/Winter) 2023

Experimental study of magnetorheological fluids formed used particle mixtures
American Physical Society, November 2021

Experimental study of magnetorheological fluids formed used particle mixtures
American Physical Society, November 2021

Transient velocity and temperature distributions in a water drop evaporating on a non-isothermal substrate
American Physical Society, November 2021

Directed self-assembly of dielectrically polydisperse nanoparticle suspensions into cohesive hierarchical patterns
American Physical Society, November 2020

Direct Numerical Simulations of Electrorheological Fluids
ASME Paper Number AJKFLUIDS2019-5452, July (3rd Quarter/Summer) 2019

Solutocapillary Flow Induced by a Freshwater Source
ASME Paper Number AJKFLUIDS2019-5576, July (3rd Quarter/Summer) 2019

Studies of flow induced on a water surface due to the impingement of a drop or a water source
American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FEDSM, October (4th Quarter/Autumn) 2017

Electric Field Driven Hierarchical Self-assembly of Monolayers of Mixtures of Particles
24th International Congress of Theoretical and Applied Mechanics (ICTAM 2016), August 2016

Fluid Dynamics of Hydrophilous Pollination in Ruppia (widgeon grass)
24th International Congress of Theoretical and Applied Mechanics (ICTAM 2016), August 2016

Fluid Dynamics of Two-Dimensional Pollination in Ruppia (widgeon grass)
ASME Paper Number FEDSM2016-7891, July (3rd Quarter/Summer) 2016

Numerical Simulations of Electric Field Driven Hierarchical Self-assembly of Monolayers of Mixtures of Particles
ASME Paper Number HTFEICNMM2016-1050, July (3rd Quarter/Summer) 2016