Granular materials are essentially a large collection of discrete solid particles. Examples include grains, cereals and pulses found in kitchen, agricultural products, sand, etc. Though encountered commonly in a variety of natural and industrial settings, understanding and predicting their flow and mixing behavior is a challenge. Part of the difficulty in predicting their behavior stems from the complex flow behavior that these materials can exhibit. For example, while an undisturbed pile of sand sits idle like solid, when filled in an hour glass, it starts to flow like a liquid! This granular flow, however, is very different from the typical liquids that we are familiar with.
A flowing stream of grains in an avalanche from Pahalgam, Kashmir! Skip to 31 sec to see the real fun.
Consider a cylindrical container filled with water and open to atmosphere with a hole at the base. The flow rate of water depends upon the height of the water level. Further, if you close the lid of the container, you may end up blocking the water flow for (unless the size of the hole is large enough). Replace the water by sand and the flow rate is no longer dependent on the fill height. Further, closing the lid will not lead to stoppage of the flow. Add a small amount of water to the sand, and the hardly any flow would be possible!
Have a look at the simulated behavior of the flow of grains from a hole at the side wall of a container. Can you see the contrast from the flow of water?
Simulation of grains flowing out of a hole at the side wall.
Granular mixtures are notorious for segregating into regions rich in only a few types of grains. This segregation could be due to difference in particle sizes, densities, surface roughness, shape etc. This makes mixing of different types of powders or bulk solids difficult. Even if you start with a well mixed granular mixture, just pouring them from one container to another can lead to segregation!
The pedagogical talks below will give you some more idea about interesting behavior of granular materials.
Segregation due to size difference while pouring material from a hopper.
Research in the group is aimed at understanding the flow behavior and segregation of granular mixtures due to differences in particle properties. We use a combination of computer simulations, experiments and theory to understand and predict the behavior of bulk solids.
One part of the effort has been dedicated in investigating the rheology of mono-disperse and multi-component granular mixtures in different flow regimes. In the case of granular mixtures, the rheology and segregation are inter-coupled. Hence, segregation of granular mixtures due to difference in density and size have been an active topic of research in our group. The fundamental understanding of segregation of binary mixtures due to difference either in density or in size based on computation of particle level forces enables accurate predictions of various flow properties of interest in simple flows. Combined effect of size and density difference on segregation of mixtures are currently being investigated. In addition, efforts to extend the theory for predicting multi-component mixtures are also going on.
Quantitative simulations of powders and other bulk solids for trouble shooting, efficiency enhancement or better understanding of ongoing operations is another active part of the research in our lab. Sponsored/Consultancy projects funded by industries dealing with bulk solids are actively being pursued in our group. Feel free to get in touch, if interested.
PI for Initiation Grant project titled “Study of size segregation in dense flow of binary granular mixtures”. Funded by I.I.T. Kanpur. 2014-2016.
PI for project titled “Characterization of particle size and shape factor distribution of the blast furnace feed and simulation of the flow and packing of the components”. Funded by TATA Steel Ltd. 2016-2019.
PI for project titled “Analysis of Sound Spectrum of Mantras and their Relation with Geometric Patterns of Yantras”. Funded by AICTE 2022-2024.
Co-PI for project titled “Automated Question-Answering Systems for Ramayana”. Funded by AICTE 2022-2024.
Co-PI from IIT Kanpur for a multi-institute project titled “Coarse-grained CFD-DEM-PBM simulations of industrial granulating beds”. Funded by SERB 2023-2026.
Co-PI from IIT Kanpur for project titled “Experiments and modeling of pedestrian dynamics to create a designing tool for crowded public spaces”. Funded by SERB 2023-2026.
PI from IIT Kanpur for a Multi-Institute Consultancy Project titled “Zonal refining strategy to expedite dem simulations of powder flow”. Amount of Rs. 7.85 Lacs funded by two international pharmaceutical companies. 2020-2023.
PI for consultancy project titled, “Blast Furnace Burden Distribution Prediction Simulation Software”. Amount of Rs. 90.315 Lacs, Funded by Tata Steel Ltd. 2023-2026.
Book Chapters:
Anurag Tripathi, "Particulate Solids" 33-66, in Coulson and Richardson's Chemical Engineering Volume 2A: Particulate Systems and Particle Technology, Sixth Edition, Edited by Raj Chhabra & Madivala G. Basavraj, Elsevier (2019)
Anurag Tripathi, "Particulate Solids in Bulk: Storage and Flow" 67-132, in Coulson and Richardson's Chemical Engineering Volume 2A: Particulate Systems and Particle Technology, Sixth Edition, Edited by Raj Chhabra & Madivala G. Basavraj, Elsevier (2019)
Journals
L Mahto, T De, J Chakraborty, J Kumar, A. Tripathi, M Sen, W Ketterhagen, "Accelerated dem simulation of the hopper-screw feeder and tablet-press feeder using the multi-level coarse-graining technique", Powder Technology 436, 119466, DOI: https://doi.org/10.1016/j.powtec.2024.119466
T De, J Chakraborty, J Kumar, A Tripathi, M Sen, W Ketterhagen, "A particle location based multi-level coarse-graining technique for discrete element method (DEM) simulation", Powder Technology 398, 117058, DOI: https://doi.org/10.1016/j.powtec.2021.117058
Satyabrata Patro, Anurag Tripathi*, Sumit Kumar, and Anubhav Majumdar, "Unsteady granular chute flows at high inertial numbers", Phys. Rev. Fluids 8, 124303 (2023) DOI: https://doi.org/10.1103/PhysRevFluids.8.124303
Vishnu Kumar Sahu, Soniya Kumawat, Shivani Agarwal and Anurag Tripathi*, "Particle force-based density segregation theory for multi-component granular mixtures in a periodic chute flow", J. Fluid Mech. 956, A8 (2023). DOI: https://doi.org/10.1017/jfm.2023.7.
Satybrata Patro, Mahesh Prasad, Ayushi Tripathi, Puneet Kumar and Anurag Tripathi*, "Rheology of two-dimensional granular chute flows at high inertial numbers", Phys. Fluids, 33, 113321 (2021). DOI: https://doi.org/10.1063/5.0070757
Anurag Tripathi*, Alok Kumar, Mohit Nema and D. V. Khakhar, "A theory for size segregation in flowing granular mixtures based on computation of forces on a single large particle", Phys. Rev. E., 103 (3), L031301 (2021). DOI: https://doi.org/10.1103/PhysRevE.103.L031301
Aman Tripathi, Vimod Kumar, Arpit Agarwal, Anurag Tripathi*, Saprativ Basu, Arijit Chakrabarty and Samik Nag, "Quantitative DEM simulation of pellet and sinter particles using rolling friction estimated from image analysis", Powder Technology, 380, 288-302 (2021). DOI: https://doi.org/10.1016/j.powtec.2020.11.024
Arpit Agarwal, Anurag Tripathi*, Aman Tripathi, Vimod Kumar, Arijit Chakrabarty and Samik Nag, "Rolling friction measurement of slightly non-spherical particles using direct experiments and image analysis", Granular Matter 23, 60 (2021). https://doi.org/10.1007/s10035-021-01124-3.
Alok Kumar, D.V. Khakhar and Anurag Tripathi*, "Theoretical calculation of the buoyancy force on a particle in flowing granular mixtures", Phys. Rev. E 100, 042909 (2019). DOI: https://doi.org/10.1103/PhysRevE.100.042909
A. C. Balazs*, Amitabh Bhattacharya, Anurag Tripathi, Henry Shum, "Designing Bioinspired Artificial Cilia to Regulate Particle-Surface Interactions", J. Phys. Chem. Lett. 2014, 5, 10, 1691-1700. Number of citations:16. DOI: https://doi.org/10.1021/jz5004582
Anurag Tripathi, Henry Shum and A. C. Balazs*, "Fluid-driven Motion of Passive Cilia Enables the Layer to Expel Sticky Particles", Soft Matter 10, 1416-1427 (2014). Number of citations:19. DOI: https://doi.org/10.1039/C3SM52156G
Henry Shum, Anurag Tripathi, J.M. Yeomans, and A.C. Balazs*, "Active Ciliated Surfaces Expel Model Swimmers", Langmuir 29 (41), 12770 (2013). Number of citations: 22. DOI: https://doi.org/10.1021/la402783x
Anurag Tripathi, Amitabh Bhattacharya and A.C. Balazs*, "Size selectivity in cilia-particle interactions: Mimicking the behavior of suspension feeders", Langmuir 29 (14), 4616 (2013). Number of citations:15. DOI: https://doi.org/10.1021/la400318f
Anurag Tripathi and D. V. Khakhar*, "Density difference-driven segregation in a dense granular flow", J. Fluid Mech. 717, 643 (2013). Number of citations:62. DOI: https://doi.org/10.1017/jfm.2012.603
Anurag Tripathi and D. V. Khakhar*, "Rheology of binary granular mixtures in the dense flow regime", Phys. Fluids 23, 113302 (2011). Number of citations:63. DOI: https://doi.org/10.1063/1.3653276
Anurag Tripathi and D. V. Khakhar*, "Numerical simulation of the sedimentation of a sphere in a sheared granular fluid: A granular Stokes experiment", Phys. Rev. Lett. 107, 108001, (2011). Number of citations:19. DOI: https://doi.org/10.1103/PhysRevLett.107.108001
Anurag Tripathi and D. V. Khakhar*, "Steady flow of smooth, inelastic particles on a bumpy inclined plane: Hard and soft particle simulations", Phys. Rev. E 81, 041307, (2010). Number of citations:15. DOI: https://doi.org/10.1103/PhysRevE.81.041307
Peer Reviewed Conference Publications
Anurag Tripathi* and Mohit Nema, "Size segregation of binary granular mixtures: Towards more appropriate scaling of percolation velocity", EPJ web of conferences 140, 03082 (2017) DOI: https://doi.org/10.1051/epjconf/201714003082
Aman Tripathi, Vimod Kumar, Saprativ Basu, Samik Nag and Anurag Tripathi*, "Characterization of the blast furnace feed components using laboratory experiments and DEM simulations", 3rd International Conference on Science and Technology of Ironmaking and Steelmaking (STIS-2017), I.I.T. Kanpur, Dec. 11-13, 2017.
Oral Presentations in conferences:
Suchintika Chanda, Abhishek Tiwari, Soniya Kumawat and Anurag Tripathi*, Continuum simulation of granular flows in rotating cylinder and orifice flows through rectangular hopper, DAE-BRNS Symposium on Advances in Atomistic and Continuum Modeling-2024, Anushaktinagar, Mumbai 400094, Oct. 23-26, 2024.
Anurag Tripathi*, “Multi-disciplinary Challenges in the Study of Itihasa Texts”, Unravelling Indian Knowledge Across Asia (UNIKAA 2024), IIT Guwahati, Assam, Oct. 3-5, 2024.
Anurag Tripathi*, Soniya Kumawat and Vishnu Sahu, “Segregation of binary granular mixtures in free surface flows”, Perspectives in Hydrodynamics, IIT Bombay, Mumbai, 400076, Feb 26-28, 2024.
Satyabrata Patro, Anurag Tripathi*, Tarun De, “Inertial number based rheology for rapid granular flows”, IUTAM Symposium on Rapid Granular Flows and Turbulent Particle Suspensions, IIT Bombay, Mumbai, 400076, Jan 21-25, 2024.
Anurag Tripathi, Satyabrata Patro, Sumit Kumar and Anubhav Majumdar, “Predicting time dependent behavior of surface granular flows”, 10th international conference on Conveying and Handling of Particulate Solids (CHoPS) 2022, Salerno, Italy, July 5-9, 2022.
Aman Tripathi, Vimod Kumar, Saprativ Basu, Samik Nag and Anurag Tripathi, "DEM parameter calibration for simulating industrial granular feed using image processing and experiments", 7th International Congress on Computational Mechanics and Simulation (ICCMS 2019), Indian Institute of Technology Mandi, India 11-13th December 2019. (Invited talk)
Anurag Tripathi, Mahesh Prasad, Arijit Chakraborty, and Satyabrata Patro, "Granular Rheology at High Inertial Numbers", CompFlu2018, Indian Institute of Technology Roorkee, 6-9th Dec. 2018. (Invited talk)
Anurag Tripathi, Mahesh Prasad, Puneet Kumar & Ayushi Tripathi, "Steady chute flow of inelastic discs beyond the maximum angle from μ-I rheology", 71st Annual Meeting of APS DFD, Atlanta, Georgia, Nov.18-20, 2018.
Anurag Tripathi, Mohit Nema and Mahesh Prasad, "Percolation Velocity Scaling Relation for Size and Density Segregation in Flowing Granular Mixtures", CompFlu2017, IIT Madras, Dec. 18-20, 2017.
Anurag Tripathi, Mohit Nema and Mahesh Prasad, "Comparison of percolation velocity scalings due to size or density difference in binary granular mixtures", Particles 2017, Hannover, Germany, 26-28th Sept. 2017. (Invited talk)
Anurag Tripathi, I. S. Dalal, I. Prashant, A. Kale and S.P. Jain, ``Modelling of Indian pedestrian behaviour using experiments and simulations", Soft Matter: Young Investigators Meet 2016, Goa, India, Dec.16-18, 2016.
Anurag Tripathi and Mohit Nema, "Size segregation of binary granular mixtures", Chemference-2016, Indian Institute of Technology Gandhinagar, India, Dec.3-4, 2016. (Invited talk)
Anurag Tripathi and Mohit Nema, ``Size segregation of binary granular mixtures flowing over inclined plane", Second International Conference on Powder, Granule and Bulk Solids: Innovations and Applications (PGBSIA 2016), Jaipur, India, Dec.1-3, 2016.
Anurag Tripathi and D.V. Khakhar, "Rheology of granular mixtures in dense flows", CompFlu2014, JNCASR, Bangalore, India, Dec. 22-24, 2014. (Invited talk)
Anurag Tripathi, Henry Shum and Anna C. Balazs, "Harnessing Passive Cilia for Surface Cleaning of Microfluidic Devices", 66th Annual Meeting of the APS Division of Fluid Dynamics, Pittsburgh, Pennsylvania, USA, Nov. 24-26, 2013.
Anurag Tripathi, Amitabh Bhattacharya and Anna C. Balazs, "Size based separation of micro-particles using adhesive ciliated surfaces: Mimicking the behaviour of suspension feeders", American Physical Society March Meeting 2013, Baltimore, Maryland, USA, Mar. 18-22, 2013.
Anurag Tripathi, Amitabh Bhattacharya and Anna C. Balazs, "Size based separation of micro-particles using adhesive ciliated surfaces", 65th Annual Meeting of American Physical Society - Division of Fluid Dynamics, San Diego, California, USA, Nov. 18-20, 2012.
Anurag Tripathi and D. V. Khakhar, "Rheology of Granular Mixtures Differing in Size and/or Density", 63rd Annual Meeting of American Physical Society - Division of Fluid Dynamics, Longbeach, California, USA, Nov. 21-23, 2010.
Anurag Tripathi and D. V. Khakhar, "Density Segregation of Granular Materials", Research Scholars Symposium, Dept. of Chemical Engineering, IIT Bombay 2010, Indian Institute of Technology Bombay, Feb. 06, 2010.
Anurag Tripathi and D. V. Khakhar, "Density Segregation of Granular Materials", 62nd Annual Meeting of American Physical Society - Division of Fluid Dynamics, Minneapolis, Minnesota, USA, Nov. 22-24, 2009.
Anurag Tripathi and D. V. Khakhar, "Chute Flow of Smooth Particles: Hard and Soft Particle Simulations", The 4th Asian Particle Technology Symposium (APT2009), New Delhi, India, Sept. 14-16, 2009.
Anurag Tripathi and D. V. Khakhar, "Transport Coefficients in Shallow Particulate Flows", ChEmference09, Indian Institute of Technology Madras, Chennai, India, Aug 22-23, 2009.
Instructor
Transport Phenomena
Introduction to Granular Mechanics
Heat Transfer and Applications
Unit Operations Lab I & II
Tutor
Fluid Mechanics and Rate Processes
Solid Mechanics
Award of Excellence in Ph.D. Thesis in the Department of Chemical Engineering, Indian Institute of Technology, Bombay for the year 2009-2011.
'Travel grant award' American Physical Society-Division of Fluid Dynamics (APS-DFD), 63rd Annual Meeting of APS-DFD 2010, Longbeach, CA.
'Best oral presentation award' at Research Scholar Symposium 2010, IIT Bombay, Mumbai 2010.
'Young scientist travel grant' Council of Scientific & Industrial Research, Govt. of India for attending the 62nd Annual Meeting of APS-DFD 2009, Minneapolis, Minnesota.
'Best oral presentation award' at national level conference ChEmference09, IIT Madras, Chennai 2009.
अनन्तं च शास्त्रं बहुला च विद्या अल्पश्च कालो बहु विघ्नता च || यत्सारभूतं तदुपासितव्यं हंसो यथा क्षीरामिवाम्बुमध्यात् ||
I am interested in exploring Itihaas (Ramayana and Mahabharata) and Puranas from both traditional as well as modern perspective. In addition, I am also exploring various aspects of Indian paradigm of life. If you are passionate about any of these and would like to join this journey, feel free to get in touch.
If interested in doing an internship/project, feel free to get in touch if you satisfy one or more of the following criteria
0. Passionate about understanding the physics of granular media/complex fluids
Good at coding in C/C++/Python/Matlab/CUDA
Interested in parallel programming using openmp/MPI/GPU. Previous experience would be highly valuable
Have experience in Discrete Element Method (DEM) simulations using LIGGGHTS/LAMMPS/other open-source DEM software
Expertise in continuum simulations of complex fluids and/or multiphase flows
Enjoy theoretical/numerical solutions of Partial Differential Equations describing mass, momentum and energy balance
In some cases, exceptional sincerity, outstanding dedication and extreme hard work can compensate well for the lack of experience. So feel free to get in touch, if that describes you.
Email : anuragt[AT]iitk.ac.in;
Office : FB 467, Dept. of Chemical Engineering, I.I.T. Kanpur; Phone : +91-512-259-6591
Lab : NL-II/306, Dept. of Chemical Engineering, I.I.T. Kanpur; Phone : +91-512-259-6820