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Prime Minister's Research Fellow

Microfluidics and Microscale Transport Processes Laboratory,

Mechanical Engineering, IIT GUWAHATI

Curriculum vitae

DHANANJAY  KUMAR

Dhananjay Kumar is currently pursuing his Ph.D. in Mechanical Engineering at the Indian Institute of Technology Guwahati, India. His academic journey includes getting a Master of Technology (M.Tech) degree in Thermal Power Engineering from the National Institute of Technology Tiruchirappalli (NIT Trichy), Tamil Nadu, India, in July 2019, and a Bachelor of Technology (B.Tech) in Mechanical Engineering from R.P Sharma Institute of Technology, Patna, in August 2015. Joining IIT Guwahati in July 2020 under the guidance of Dr. Pranab Kumar Mondal, he was honored with the prestigious Prime Minister's Research Fellowship (PMRF). His research interests primarily revolve around vortex-induced convective mixing in microchannels. His approach involves both passive and active methods to achieve this mixing phenomenon. In passive mixing, his focus lies on a cylindrical channel configuration employing an inlet swirl to initiate tangential fluid movement and create vortices for effective mixing. Conversely, his active approach employs an external electric field in a narrow-fluidic channel with walls coated using a soft polyelectrolyte layer. This method aims to induce chaos perpendicular to the flow direction, facilitating vortex-assisted convective mixing. His dissertation emphasizes the transformative potential of both inlet swirl and the polyelectrolyte layer in reshaping Lab-on-a-Chip (LOC) or micro Total Analysis Systems (µTAS) platforms. These studies are anticipated to enhance functionalities in various fields, including biological, clinical, and pathological devices, as well as artificial implants.

Dr. Pranab Kumar Mondal (Associate Professor)​

C-101 (office), ME FF2A lab,​

Department of Mechanical Engineering, IIT Guwahati​

Guwahati 781039​

Ph:- 0361-2583435​

Fax:​- 0361-2582699

Email:- pranabm@iitg.ac.in

Dr. Pranab K. Mondal is an Associate Professor in the department of Mechanical Engineering at Indian Institute of Technology Guwahati since May 2015. He received his undergraduate and postgraduate degree from Jadavpur University, Kolkata, and completed his Ph.D. from Indian Institute of Technology Kharagpur in 2015. He worked as a Research Associate at IIT Khargpur for nearly one year before joining IIT Guwahati. He has taught several courses, including Fluid Mechanics, Applied Thermodynamics, Thermodynamics, Fundamentals of Microfluidics, Experimental Methods in Fluid Mechanics to both undergraduate and post graduate students at IIT Guwahati. Among His principal research interest, encompassing the broad area of Microfluidics has covered various facets of microscale multiphase transport, electrokinetics, microscale transport of heat and experimental microfluidics. He is currently working on droplet-based microfluidics, magnetofluidics, experimental investigations of capillary filling of bio-fluids.

Courses undertaken during Ph.D.

Courses Course Name Grade CPI
ME 501 Advanced Engineering Mathematics BB
ME 520 Fluid Mechanics AB 8.75
ME 521 Conduction and Radiation AB
ME 543 Computational Fluid Dynamics AB

Hobbies

  • Cricket
  • Badminton
  • Reading, Teaching and Learning
  • Swimming
  • Pranayama
  • Listening Music

Technical Skills

  • C, C++
  • MATLAB
  • MS Office
  • ANSYS, COMSOL Multiphysics
  • Latex
  • Mendeley

Education

  • Ph.D. Research Scholar (September 2020 - Present)

    Indian Institute of Technology, Guwahati

    Department of Mechanical Engineering (Microfluidic and Microscale)

    Fellowship : Prime Minister's Research Fellowship (September 2020 - Present)

    Research Topic : Vortex-induced convective mixing in a microchannel.​

  • M.Tech (2017-2019)

  • B.Tech (2011-2015)

Teaching Assistant (TA)

  • Teaching (March 2021-2022) at North Gauhati College

  • Teaching Assistant (March 2022-Present) at Assam Don Bosco University School of Technology

Research Objective

Addressing the unique challenges posed by their small scale is crucial in microdevices, particularly in manipulating small sample quantities, such as expensive or hazardous materials like DNA. Microdevices offer high-quality separation and rapid detection processes, reducing analysis time, and their compact size, portability, and disposability enhance their appeal. Typically, microfluidic devices have dimensions below 1 mm and above 100 µm. At the microscale level, laminar flow, characterized by a low Reynolds number and viscosity dominance, relies solely on molecular diffusion for mixing, presenting a challenge for effective fluid blending. Efficient mixing is essential to match biological response times, chemical reaction rates, and gradients of essential microlevel species. The present research aims to explore strategies for enhancing mixing in microfluidic devices through passive and active methods. The passive approach involves introducing inlet swirl to induce tangential flow in the bulk fluid, promoting efficient mixing through vortical patterns near the channel inlet. Additionally, tangential velocity at the inlet is investigated to enhance mixing of inelastic non-Newtonian fluids or solutes at the outlet, considering nonlinear viscous effects like shear-thinning and shear-thickening. Furthermore, the study examines the impact of soft polyelectrolyte layers on inner channel walls to induce chaos perpendicular to the flow direction, facilitating vortex-assisted convective mixing. The research extends to pH-dependent polyelectrolyte layers, exploring how modulation of electroosmotic vortices can achieve effective mixing by varying solution pH and rheology, especially for non-Newtonian fluids. This dissertation underscores the transformative potential of both inlet swirl and polyelectrolyte layers in reshaping Lab-on-a-Chip (LOC) or micro Total Analysis Systems (µTAS) platforms. These advancements are poised to enhance functionalities across various fields, including biological, clinical, and pathological devices, as well as artificial implants.

Objective 1

  • Effective solute mixing of a Newtonian fluid within a cylindrical narrow fluidic channel, specifically in the presence of an inlet swirl

    Our first objective focuses on investigating the flow of Newtonian fluids through a narrow cylindrical fluidic channel. This involves solving the Navier-Stokes (NS) equation to derive analytical expressions for both axial and tangential (or swirl) velocities. To address the numerical solution of the scalar species transport equation, we integrate the analytically derived velocity fields. Following this, we conduct a thorough analysis of the effectiveness of solute mixing, considering the inlet swirl responsible for the bulk rotation of the fluid in the tangential direction. This analysis involves a comprehensive evaluation that includes both qualitative and quantitative assessments. It explores a defined set of parameters, such as Reynolds number and Peclet number, with a specific emphasis on practical applications.

  • Objective2

  • Effective solute mixing of a non-Newtonian fluid within a cylindrical narrow fluidic channel, specifically in the presence of an inlet swirl

    The second objective extends the initial investigation to encompass non Newtonian fluids. This entails solving the Navier-Stokes (NS) equation with a focus on deriving analytical expressions for axial and tangential (or swirl) velocities using the power-law scheme. Additionally, we incorporate the derived velocity field expressions into the scalar species transport equation and solve it numerically. Subsequently, a comprehensive examination of the effectiveness of solute mixing is carried out, encompassing both qualitative and quantitative assessments. In this analysis, the prominent role of inlet swirl becomes evident in achieving efficient mixing, attributed to the bulk rotation of fluid in the tangential direction. This effect is particularly pronounced with an increase in shear-thinning fluid compared to shear-thickening fluid. The assessment covers a specific set of parameters, emphasizing their practical applications, which include considerations of Reynolds number and the power-law index.

  • Objective3

  • Effective solute mixing of non-Newtonian fluid through the modulation of electroosmotic vortices using a soft polyelectrolyte layer

    In the third objective, we employed numerical methods to explore the transport and mixing behavior of biofluids exhibiting non-Newtonian characteristics. This study investigates the impact of polyelectrolyte layer (PEL)-modulated electrostatics, fluid rheology, and frictional drag on biofluids. The expectation is a notable rise in flow velocity due to electroosmotic actuation, counteracted by increased frictional drag potentially reducing flow velocity. The research specifically examines the influence of patterned PEL structures on vortical flow and associated mixing phenomena. The study conducts various analyses with different patterns under the same set of parameters, focusing on practical applications and interpreting the implications of each configuration. Furthermore, the research investigates how the PEL affects mixing length and the initiation of recirculation zones to achieve better mixing within a short length scale in the given problem.

  • Objective4

  • Effective solute mixing of non-Newtonian fluid through the modulation of electroosmotic vortices using a pH-dependent soft polyelectrolyte layer

    The fourth objective investigated here extends the third by introducing a pH dependent soft polyelectrolyte layer (PEL) structure within the narrow fluidic channel while maintaining the effects of fluid rheology. This investigation delves into the combined impact of pH-dependent PEL-modulated electrostatics, fluid rheology, and solution bulk pH on biofluids. The primary goal is to explore the characteristics of a non-Newtonian vortex influenced by a pH-sensitive PEL modulated electroosmotic effect in a microchannel. The study specifically focuses on the influence of pH-sensitive PEL structures on vortical flow and associated mixing phenomena. Utilizing various analyses with different patterns under consistent parameters, the research emphasizes practical applications and interprets the implications of each configuration. Ultimately, the study's findings may significantly influence the design of microfluidic devices tailored for mixing and transporting non-Newtonian liquids at specific bulk pH values.

  • Further Research Work

  • To investigate Droplet-based mixing in a microfluidic channel under magnetic field variation: an experimental and numerical study

    Our objective is to obtained the droplet based efficient mixing in a crossflow T-junction with Mineral oil as continuous phase and DI Water based ferrofluid as dispersed phase under the uniform magnetic field.

  • Publications

    Ph.D. Journal: Publications from the Present Thesis

      Kumar, D., Mehta, S. K., and Mondal, P. K. (2024) Non-Newtonian solute mixing via protonic exchange of Polyelectrolyte layer: Unveiling formation of electroosmotic vortices, Soft Matter [SM-ART-01-2024-000046].

      Kumar, D., and Mondal, P. K. (2024) Mixing of inelastic non-Newtonian fluids with inlet swirl, Journal of Fluid Mechanics [Revised version under review: JFM-23-1730.R1].

    Ph.D. Journal: Other Publications

    M.Tech Journal

    Ph.D. Conference Publication [Book Chapter]:

    Ph.D. Conference Presentation:

      Mehta, S. K.,Kumar, D., Mondal, P. K., and Wongwises, S. (2023) “Effect of Thermal Dispersion on Thermo-Hydraulic Characteristics for Flow through Wavy Solar Power Plant with Metallic Porous Blocks”, ESDA2022, 5th International Conference, [Best Paper, Paper ID: 18].

    Achievements

    • Recipient of the prestigious Prime Minister's Research Fellowship (September 2020 - 2024).
    • Awarded as Teaching Assistant for the NPTEL Online Certification course “IC Engines and Gas Turbines” held at IIT Guwahati, India, from January to April in 2022, 2023, and 2024.
    • Awarded as Teaching Assistant for the NPTEL Online Certification course “Principal of Hydraulic Machines And System Design” held from July-October 2023 and 2024, IIT Guwahati, India.
    • Recipient of Best Paper award “5th International Conference on ESDA 2022” held from 31st December 2022 - 1st january 2023 at Kolkata, India.
    • Participated in the “9th International and 49th National Conference of Fluid Mechanics and Fluid Power (FMFP 2022)” held during 14th-16th December 2022 at IIT Roorkee, India.
    • Participated in the “48th National Conference on Fluid Mechanics and Fluid Power (FMFP-2021)” held from 27th-29th December 2021 at BITS Pilani, Pilani Campus, Rajasthan, India.
    • 2nd Rank holder in PG during the year 2017-19, M.Tech, NIT Tiruchirappalli.
    • Award of excellence for highest attendance and performance for session 2014-15, B.Tech, RPSIT, Patna.

    Extra-Curricular Activities

    • Participated in an international exchange program carried out under the framework of “Japan Asia Youth Exchange Program in Science (Sakura Exchange Program in Science)” held from 9th - 14th June 2024 at Kyushu Institute of Technology, Japan.
    • Participated in Online workshop on “High Heat Flux Thermal Management Systems” held from 16th- 17th March 2024 at IIT Guwahati.
    • Participated in Online workshop on “Machine Learning & Deep Learning Techniques with Applications” held from 7th - 11th January 2023 at IIT Guwahati.
    • Participated in Online workshop on “Blast and Shock Resistant Bio-inspired Functional Materials Design Methodologies” held from 10th -19th January 2022 at IIT Guwahati.
    • Participated in “Computational Fluid Dynamics workshop” held on 15th - 16th march, 2018, NIT, Tiruchirappalli.
    • Got NCC certificate “A” at school level in 2008.

    Contact Details

    Dhananjay Kumar

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