'Crossing the Rubicon' is symbolic for crossing into an unknown territory. The Rubicon Grant is therefore awarded to exceptional researchers in the Netherlands who dare to tread new ground.

TU Delft's Sunetra Sarkar, from India, will use her Rubicon Grant for research that aims to crack the pattern for the aerodynamics of flapping wings. This unflappable lady explained her fascination with unsteady flows and Micro Aerial Vehicles.

It is the stuff that science-fiction movies are made of: small robotic insects and birds able to fly and maneuver in the same way as their living counterparts. Yet, in recent years, robotic insects - better known as Micro Aerial Vehicles or MAVs - have become a technological reality. TU Delft aerospace engineer and researcher Sunetra Sarkar recently won a coveted Rubicon Grant for her work on creating a computational simulation of the movement of flapping insects. Her goal is to develop a better understanding of the aerodynamics of this type of motion. The knowledge generated from her research will then serve as a basis for the further development of MAVs.

In a small space reserved for smokers at Faculty of Aerospace Engineering‘s department of Aerodynamics, Sunetra Sarkar launches into an enthusiastic explanation of unsteady aerodynamics, particle flows and the simulation of flapping insect wings. When asked how her work relates to Delft's best known MAV, the 'Delfly’, Sarkar makes one thing very clear: "My work is not at all related to Delfly," she states.

Sarkar‘s research involves developing a computational model, not a physical one. "Granted, Delfly is an example of how a MAV can be derived from a natural form, in this case a dragonfly," she says. "It is however not a precise model of a dragonfly, but rather an approximation, because it’s the size of a bird rather than of an insect."

Sarkar is from India, where she lived until moving to Holland in 2004 to do her post-doc studies at TU Delft. After completing her BSc in Civil Engineering, she received her MSc degree and PhD degree in Aerospace Engineering in Bangalore, India.

After completing her doctorate, Sarkar decided to go abroad for a year to hone her research skills at a foreign institution. "TU Delft has a good international reputation. It‘s also known for having a good working atmosphere and is respected for its quality of research," she says. "There was another possibility for me to do my post-doc at ETH Zurich, but TU Delft's offer panned out first. Also, my husband was offered a post-doc position at TU Delft, so ultimately it wasn’t a difficult choice to make."

Asked if there is a lot of red tape involved for those who want to do their post-doc in the Netherlands, Sarkar said: "TU Delft organizes all the work permits and a place to live before you arrive here. It was all taken care of. On my side in India however it was a bit more of a hassle to get the trip organized. I had to go from Bangalore to the Dutch embassy in Delhi, which took 48 hours by train to get there! India is of course a big country."
Fluid flow

The title of Sarkar‘s research project is: 'A Lagrangian discrete particle technique to simulate bio-mimetic propulsion. The Lagrangian particle based technique is a numerical tool, which uses particles to simulate fluids. Sarkar proposed using the Lagrangian technique in developing a model for the simulation of flapping insect wings.

But why flapping insects? Sarkar: "I‘ve always been interested in unsteady aerodynamics. Unsteady means some aerospace structure - be it an aircraft wing or an insect wing - that is subject to fluid flow. Unsteady means that it’s time-dependant: changing position in respect to time. A flapping insect is flapping in respect to time and changing its position in respect to time, which makes it unsteady." During her years of research, Sarkar has studied the movement of aircraft and several components of aircraft wings when subjected to different kinds of flow.

The Rubicon Grant - possibly named for the mythological river famously crossed by Julius Caesar and therefore synonymous with crossing into unknown territory - was created to encourage talented researchers to do post-doctoral research at Dutch universities and abroad. One hundred grants are awarded each year in the Netherlands in all scientific fields.

The admission requirements however are strict: applicants may only apply once and the application must be submitted within 12 months of receiving a doctorate degree. In an apparent effort to even up the playing field in the world of science, women are specifically encouraged to apply for the grants. Did this have bearing on Sarkar receiving the grant? "It could have," she replied, coolly.


Micro Aerial Vehicles (MAVs), as the name suggests, are extremely small. The maximum length of a MAV is 15 centimeters. Classical aerodynamic theory predicts the behavior of large aircraft, but fails to explain how smaller flying animals or insects are able to fly. In fact, according to the classic theories insects and small birds technically cannot fly. Development of MAVs is hindered by this knowledge gap. New data must be gathered. Many answers lie in unraveling the movements of small birds and large insects. Enter Sarkar.

"It's quite fascinating understanding the mechanism of flight," she says. "Research on the mechanism of flight of insects and birds is however rather recent. This is because it takes a lot of computational power to crack the patterns. There are only a few labs who are conducting this kind of research."

There are any numbers of applications possible for MAVs, with the most obvious being for military operations. MAVs can be used for surveillance, tagging and bio-chemical sensing. And also for spying? "People often mention this example" Sarkar replies, "but there are other important applications, such as going to much polluted areas where humans cannot go, like nuclear wastelands for instance, to gather information or take photographs. In other words, it is not for spying purposes only!"

Sunetra Sarkar. (Photo: Sam Rentmeester/FMAX)