Bang, boom, crrrassssh! The science of collisions


If you collide into Dhairya Vyas, he will apologise, break into a smile, and then give you a lecture on why collisions are important!

“From a cricket pitch where a batsman hits a ball, to a construction site where rocks are crushed,” says this mild-mannered research scholar with the IITB-Monash Research Academy, “contacts and collisions are present everywhere in our daily lives. Some occur at high speeds like a bullet hitting a target; others are slower like the dropping of a mobile phone.”

No prizes for guessing that Dhairya analyses collisions and his research project is titled, ‘Modeling Frictional Collisions with SPH’.

In industries, collisions between granular bodies are used in applications like shot peening, milling, crushing, and mixing. Since it is difficult and often expensive to use experimental techniques to analyse such applications, numerical methods like the Discrete Element Method (DEM) are used instead, reveals Dhairya.

“DEM can model frictional collisions between the interacting objects and has proven to be useful in analysing the bulk flow behaviour of granular systems. However, while analysing the flow of granules, we also need to identify how the interacting bodies deform and break, and this is not easily possible using DEM, especially in more intricate applications involving complex geometries,” he adds. “So numerical methods which can accurately model both — frictional interactions and deformation and breakage — need to be identified. One such method is Smooth Particle Hydrodynamics (SPH), which has been widely used to analyse high velocity collisions like ballistic impacts. However, it lacks accurate friction models and hasn’t been tested for analysing low velocity impacts. Therefore, in this project, we incorporate accurate friction models in SPH and test its performance in modeling low velocity collisions.”

The IITB-Monash Research Academy is a collaboration between India and Australia that endeavours to strengthen scientific relationships between the two countries. Graduate research scholars like Dhairya study for a dually-badged PhD from both IIT Bombay and Monash University, spending time at both institutions to enrich their research experience.

What got Dhairya interested in this subject?

“Computational modeling, the process of how we transform real-world occurrences like water flowing in a river or a meteorite hitting the Earth’s surface in the form of equations and numbers, has always fascinated me. What is even more interesting is that since we were initially unable to solve most such equations, we developed computers, which further transforms these numbers and equations into 1s and 0s and solves them for us. This fascination and curiosity is why I find my research exciting.”

Why should this project matter?

We hope to provide a powerful predictive tool for engineers who design equipment that is used to handle granular material. Through the help of computer simulations, they will be able to compare the durability and performance of different designs and select the most suitable ones. This will not only minimise the cost of designing (by minimising experimental tests) but also will lead to the development of durable and efficient components. This will eventually reduce the price of the finished product, says Dhairya.

An SPH render of a granule rebounding from a substrate. The goal of the project is to ensure that the rebound kinematics and the deformation of the interacting bodies is accurately modelled.

Says Prof Murali Sastry, CEO, IITB-Monash Research Academy, “The handling of particulate materials in industry often involves equipment subject to highly abrasive conditions leading to progressive wear of the equipment and reduced process efficiencies. Despite the significant costs of wear and erosion, there has been little work done in its numerical simulation. This project will help shed light on this relatively unexplored area.”

Yes, there is lots to learn from researchers like Dhairya Vyas. We hope you collide into him soon!

Research scholar: Dhairya Vyas, IITB-Monash Research Academy

Project title: Modeling Frictional Collisions with SPH

Supported by: Data61, CSIRO

Supervisors: Prof. Devang Khakhar, Prof. Murray Rudman, Dr. Sharen Cummins, Dr. Gary Delaney,

Contact details: dhairyarvyas@gmail.com

This story was written by Mr Krishna Warrier based on inputs from the research student, his supervisors, and the IITB-Monash Research Academy. Copyright IITB-Monash Research Academy.