Reseasrch Assistant

Summary
Doctoral candidate in chemical engineering, graduating in August •••••,
seeks a challenging full time position to apply research experience
and skills in R&D and/or process engineering in chemicals and materials
manufacturing. Extensive experience in mesoscopic and continuum-level
simulations, modeling, data analysis in particulate and materials processes.
Strengths include excellent knowledge of numerical
simulations, analytical and problem solving ability, and proven
communication skills and experience in supervising, assisting and
lecturing undergraduate students in course work.



Education:

Washington University,Saint Louis, MO
Doctoral Program, Chemical Engineering
Graduation: August •••••
GPA: •••••/•••••


University of Maryland, College Park, MD
Master of Engg, Mechanical Engineering.
Graduation: August •••••
GPA: •••••/•••••


Indian Institute of Technology, Bombay, India
Mater of Tech, Chemical Engineering.
Graduation: July •••••
GPA: •••••/•••••


Indian Institute of Technology, Bombay, India
Bachelor of Tech, Chemical Engineering.
Graduation: July •••••
GPA: •••••/•••••




Research

*Numerical Simulation of Formation of Integral-skin Polyurethane Foam (DST)
*Linear Stability Analysis of Polymeric Fluids in complex industrially
applied geometries (NSF)
*Turbulent Drag Reduction by Macromolecular Additives (DARPA)
*Brownian Dynamics Simulation (DARPA)
*Passive Scalar Transport in Viscoelastic Turbulent channel Flow (DARPA)


Professional Experience

Washington University, St. Louis, MO Research Assistant••••••••••present
Developed a numerical simulation code for analyzing the linear stability analysis of Taylor-Couette (TC) flow of semi dilute non-Brownian fiber suspensions. Proposed a mechanism to explain the observed stabilization.
Developed an algorithm that combines Brownian dynamics simulation (BDS) with direct numerical simulation (DNS) to study the polymer chain dynamics in Newtonian and viscoelastic turbulent channel flow.
Developed a numerical simulation code to study the transport of passive scalar (heat) in a viscoelastic turbulent channel flow via direct numerical simulation technique.
Proposed eddy viscosity expressions in the viscoelastic turbulent channel flow in three distinct regimes of DR.
Developed a numerical simulation code for studying the influence of fiber additives on turbulent structures in turbulent channel flow and for predicting the fiber induced turbulent drag reduction.
Developed a new model, based on introducing an adaptive length scale (ALS) as an internal variable, for flows with strong shear components to reproduce the fine scale physics of the Kramers chain.

Washington University, St. Louis, MO Teaching Assistant••••••••••
Delivered lectures, graded assignments, proctored examinations, and conducted help sessions for undergraduate course on transport phenomenon.

University of Maryland, College Park, MD Teaching Assistant••••••••••
Delivered lectures, graded assignments, proctored examinations, and conducted help sessions for undergraduate course on introduction to fluid mechanics.
Administered the fluid mechanics laboratory, troubleshot experimental problems, commissioned new experimental setups, and graded laboratory reports.

Indian Institute of Technology, Bombay, India Research Assistant••••••••••
Developed a model for describing the expansion of polyurethane (PU) Foam in a closed mold. It is solved for temperature, pressure, conversion and density at any instant and any position in the mold. I further verified the model development via conducting laboratory experiments.


Indian Institute of Technology, Bombay, India Teaching Assistant••••••••••
Delivered lectures, graded assignments, proctored examinations, and conducted help sessions for undergraduate course on introduction to fluid mechanics.
Administered the fluid mechanics laboratory, troubleshot experimental problems, commissioned new experimental setups, and graded laboratory reports.



Skills
Computer
Languages: C•••••, C, FORTRAN
Operating systems: Windows, Unix, Linux, DOS
Engineering software: ANSYS, TECHPLOT

Analytical

Numeric Discretization: Finite elements methods (FEM), finite differences, Chebyshev-Fourier Collocation
Numerical Integration: Chebyshev-Fourier Space Integration, Operator-Splitting Time Integration schemes

Laboratory/Experimental

Have an experience working with Reaction Injection Molding (RIM) machine as a master student at I.I.T. Bombay (India)


Publications

••••• V. ••••• and D. V. Khakhar, Formation of integral skin polyurethane foams, Poly. Eng. Sci. •••••, ••••• (•••••)
••••• V. K. •••••, R. Sureshkumar and B. Khomami, Centrifugal instability of semi dilute non-Brownian fiber •••••. Fluid. •••••, 6, •••••, •••••
••••• V. K. •••••, R. Sureshkumar and B. Khomami, Polymer chain dynamics in Newtonian and viscoelastic turbulent channel flows. Phys. Fluid. •••••, 5, •••••, •••••
••••• V. K. •••••, R. Sureshkumar and B. Khomami, Passive scalar transport in polymer drag reduced turbulent channel •••••E J. •••••, 7, •••••, •••••
••••• V. K. •••••, R. Sureshkumar and B. Khomami, Eddy viscosity in viscoelastic turbulent channel flow. Submitted to J. Non-Newtonian Fluid Mech. (•••••).
••••• V. K. ••••• and B. Khomami, A new model for dilute polymer solutions in flows with strong shear components. To be submitted to J. Non-Newtonian Fluid Mech.
••••• V. K. •••••, R. Sureshkumar and B. Khomami, Fiber induced drag reduction in a turbulent channel flow. Work in progress.


Presentation

••••• ••••• •••••, Radhakrishna Sureshkumar, Bamin Khomami and J. Azaiez, Influence of fiber additives on the stability of Taylor-Couette flow. Proc. ••••• SOR •••••rd Annual Meeting, Bethesda, Maryland, USA (•••••).
••••• ••••• •••••, Radhakrishna Sureshkumar, Bamin Khomami and J. Azaiez,Linear Stability of Taylor-Couette Flow of Semi-Dilute Non-Brownian Fiber Suspension. Proc. ••••• AIChE Annual Meeting, Reno, NV, USA (•••••)
••••• ••••• •••••, Radhakrishna Sureshkumar and Bamin Khomami, Polymer chain dynamics in drag reducing flows: A multiscale approach. Proc. ••••• SOR •••••th Annual Meeting, Minneapolis, Minnesota, USA (•••••).
••••• ••••• •••••, Radhakrishna Sureshkumar and Bamin Khomami,Multiscale simulation of polymer chain dynamics in drag reducing flows. Proc. ••••• AIChE Annual Meeting, Indianapolis, Indiana, USA (•••••).
••••• ••••• •••••, Radhakrishna Sureshkumar and Bamin Khomami, Polymer chain dynamics in turbulent channel flow, Division of Fluid Dynamics •••••th Annual Meeting, Dallas, Texas, USA (•••••).
••••• ••••• •••••, Chang Li, Radhakrishna Sureshkumar and Bamin Khomami, Numerical Simulation of Polymer chain dynamics in turbulent channel flow, Thirteenth International Workshop on Numerical Methods for Viscoelastic Flows, Lausanne, Switzerland, June (•••••).
••••• ••••• •••••, Chang Li, Radhakrishna Sureshkumar and Bamin Khomami, Polymer chain dynamics and turbulent bursts: A mechanism of drag reduction, Proc. ••••• SOR •••••th Annual Meeting, Pittsburgh, Pennsylvania, USA (•••••).
••••• ••••• •••••, Chang Li, Radhakrishna Sureshkumar and Bamin Khomami, Polymer chain dynamics in drag-reduced turbulent channel flow, Proc. ••••• AIChE Annual Meeting, San Francisco, California, USA (•••••).
••••• Chang Li, Radhakrishna Sureshkumar, Bamin Khomami and ••••• •••••, Ejections and bursts in turbulent channel flow of dilute polymer solutions, Division of Fluid Dynamics •••••th Annual Meeting, East Rutherford, New Jersey, USA (•••••).
••••• Chang Li, ••••• •••••, Radhakrishna Sureshkumar and Bamin Khomami, Polymer induced turbulent drag reduction: a mechanistic study, Fourteenth International Congress on Rheology (ICR•••••), Seoul, South Korea (•••••).
••••• Bamin Khomami, Radhakrishna Sureshkumar and ••••• •••••, Passive scalar transport in polymer drag reduced turbulent channel flows, Division of Fluid Dynamics •••••th Annual Meeting, Seattle, Washington, USA (•••••).

Academic Projects

Process Design for the Liquefaction of CO2:
Liquefied CO2 has wide variety of applications. There are several ways to achieve liquefaction e.g. by heat exchange at constant pressure, by expansion in a turbine from which work is obtained and by a throttling process. I worked on the Linde process utilizing throttling process to achieve liquefaction of carbon dioxide.

Preparation of Integral-Skin Polyurethane Foam:
I developed a model describing the expansion of polyurethane (PU) Foam in a closed mold. The model developed is highly non-linear. It is solved for temperature, pressure, conversion and density at any instant and position in the mold using an explicit finite difference method. I found that all these variables are a function of time as well as position inside the mold except for pressure, which is a function of time only. I did experiments to verify the model.

Theories of Transport in Ion-Exchange Membranes:
I reviewed and presented the Space Charge Model for ion-exchange membranes. This model is useful in describing various phenomena pertaining to selective transport of electrolytes inside the membrane pore.

A lamellar model for analysis of Rapidly-Mixed Fast-Cross linking Exothermic Polymerization:
I studied Reaction Injection Molding (RIM), a relatively new process in which two or more monomer streams are rapidly contacted by impingement and conveyed to a mold cavity where polymerization proceeds. A lamellar mixing approach to this problem was studied as opposed to a perfect mixing model, which seems improbable in many cases.

Dow Polymerization Reactor:
I wrote a simulation code in Fortran••••• to simulate the behavior of a process in a jacketed polymerization reactor developed by Dow Chemicals.

Basic Fundamental Conditions For Predicting mixing in •••••D Time-Periodic Flows:
First I reviewed the existing literature on mixing. Then later I developed a computer simulation for solving the flow field inside a cavity, which is the model representation of an extruder. Then I incorporated the tracking of a blob in the existing simulation.

Linear Stability Analysis of the Taylor-Couette flow of semi-dilute non-Brownian Suspension:
Linear stability of the Taylor-Couette (TC) flow of semi-dilute non-Brownian suspension is investigated by utilizing the fiber orientation model developed by Hinch and Leal in conjunction with a quadratic and hybrid closure proposed by Advani and Tucker. It is found that irrespective of the closure approximation used the fiber additives suppress the centrifugal TC instability, i.e., the critical Reynolds number (Re) increases with the fiber volume fraction and aspect ratio as well as the inter-fiber interaction coefficient.

Polymer Chain Dynamics in Newtonian and viscoelastic Turbulent Channel Flow:
Brownian dynamics simulations utilizing FENE and FENE-P dumbbell models examine polymer chain dynamics in Newtonian and viscoelastic turbulent channel flows. The influence of maximum extensibility of the polymer chain, b, the friction Reynolds number, Ret, and friction Weissenberg number, Wet, on the chain dynamics in the viscous sublayer, buffer layer and turbulent core is examined. For a given value of b, the average chain extension, <Q>, approaches an asymptotic value with increasing Wet. For given values of Wet and the friction Reynolds number, Ret, <Q>/b decreases although <Q> itself increases with increasing b. Significant qualitative and quantitative differences exist between the predictions obtained using Newtonian and viscoelastic kinematics. In particular larger <Q> values are obtained in the viscoelastic turbulent channel flow than that in the Newtonian one indicating that the coupling of the flow field with the polymer configuration has a strong influence on the chain extension. Significant qualitative and quantitative differences also exist between the predictions obtained using the FENE and FENE-P models. Specifically, <Q> values predicted by the FENE-P model are greater than those predicted by the FENE model for given Wet and b.

Passive Scalar Transport in Viscoelastic Turbulent Channel Flow:
Passive scalar transport in turbulent channel flow of viscoelastic dilute polymer solutions exhibiting drag reduction (DR) is studied using direct numerical simulations for DR values up to •••••%. DR is accompanied by the stabilization of low speed streaks in the buffer layer, which are primarily responsible for the streamwise heat transport. Moreover, as DR increases, the Reynolds stress and the root mean square fluctuations in the wall-normal and spanwise velocity components decrease. Hence, as DR is increased, streamwise heat flux increases while both wall-normal and spanwise heat fluxes decrease. Consequently, for large DR values, the flow acts as a highly efficient heat pump.

Eddy Viscosity in Viscoelastic Turbulent Channel Flow:
Eddy viscosity model prediction in turbulent channel flow of viscoelastic dilute polymer solutions exhibiting drag reduction (DR) is studied using direct numerical simulations for DR values up to •••••%. The expressions for eddy viscosity model vary with the extent of DR. Three distinct regimes of DR; namely, LDR, HDR and MDR are shown to have a unique expression for eddy viscosity model in each. Based on these expressions a procedure for predicting mean velocity profile in turbulent channel flow of viscoelastic dilute polymer solutions is proposed. A good agreement between the model predictions and DNS results for mean velocity profile is obtained.

Adaptive Length Scale (ALS) model for dilute polymer solutions in flows with strong shear components:
A new model, based on introducing an adaptive length scale (ALS) as an internal variable, is developed for flows with strong shear components to reproduce the fine scale physics of the Kramers chain. The ALS-model describes the polymer molecule as a set of identical segments in which each segment represents a fragment of the polymer that is short enough so that in can sample its entire configuration space on the time scale of an imposed deformation and therefore stretch reversibly. As the molecule unravels, the number of the segments decreases, but the maximum length of each segment increases, so that the constant maximum contour length of the molecule is preserved.

Fiber Induced Turbulent Drag Reduction:
In this project, I performed from first principles a direct numerical simulation (DNS) of a fully turbulent channel flow of a
semi dilute fiber suspension. Drag reductions of up to •••••% are predicted. Flow statistics show trends similar to those observed in
simulation of polymer induced turbulent drag reduction: Reynolds stresses are reduced, velocity fluctuations in the wall-normal
and spanwise directions are reduced while streamwise fluctuations are increased, and streamwise vorticity is reduced.



Honors and Activities

The best Teaching Assistant award for ••••• at Washington University in Saint Louis.
The best Graduate Student Seminar Speaker for ••••• at Washington University in Saint Louis.

References

Available upon request.