Bulk Solids & Complex Fluids Research Lab

Grains grains every where ...

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.

The unusual Liquid

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.

Thou Shall not mix! 

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.

Pedagogical Lectures

Research 

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 (details not mentioned due to confidentiality clause). Feel free to get in touch, if interested.

Publications

Book Chapters:

Journals 

Conferences

Peer Reviewed Conference Publications

Oral Presentations in conferences:


Teaching

Instructor 

Transport Phenomena

Introduction to Granular Mechanics 

Heat Transfer and Applications

Unit Operations Lab I & II

Tutor

Fluid Mechanics and Rate Processes

Solid Mechanics

Awards

Other interests

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. 

Opportunity for Students

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


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. 

Contact

Email : anuragt[AT]iitk.ac.in;

Office :  FB 465, 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