The Fluid Dynamics Simplification

Apparently we breathe air between 8 and 14 times a minute. Despite this a physicist may tell you that air is negligible, insignificant, of no concern. The reason for this is physics sometimes needs to be simplified to work. One of the most common simplifications is to ignore air resistance altogether. At the point at which air becomes a concern it becomes its own subject: Aerodynamics, a smaller part of Fluid Dynamics. To fully appreciate the topic of Fluid Dynamics, I spoke to Jamie Nutter, a PhD student studying that very topic at Imperial College London.

An Interview with a Fluids Researcher

Me: "Why did you choose to study Fluid Dynamics?"

Jamie: "I’ve always been a fan of F1 and so aero always appealed to me in that way. But I think mainly it was Prof Vladimir Vladimirov (My masters supervisor) who sparked a real interesting in aero while I was doing my masters project. He was the one who first suggested the idea of doing a PhD and encouraged me to pursue one in Fluids."

* Of course Fluid Dynamics has more important applications that just racing. However, Sebastian Vettel would have definitely not won the F1 championship if his team were not considering a whole collection of Fluid Dynamics funk. The effect of air battering the Formula 1 really does affect its performance.*

Me: "Can you tell me a little bit about your research?"

J: "My research is in laminar flow control, funded in part by Airbus, essentially we are looking at the mechanism by which flow over an aerofoil becomes turbulent and attempting to understand and design controls to encourage a more laminar aerofoil. This is to reduce the drag caused by the aerofoil and lead to a reduction in fuel costs. "

** So Jamie looks into how turbulent (rough) flow is created and what mechanisms can encourage a more laminar (smooth) flow. Seeing is believing and below show a picture of turbulent and laminar flow of candle smoke. **

Laminar and turbulent candle smoke. When the smoke rises it starts off laminar, as it continues upwards it gets affected by the air, ultimately creating turbulent smoke. Image courtesy of a Google search.

Jamie continued to explain his research in finer, more technical detail:

J: "We do this by considering asymptotic approximations to the Navier-Stokes equations.
Specifically my work has been in two parts. Firstly I considered a wave like instability (called a Tollmein-Schliching wave) and looked at the effect of having a flow over an aerofoil with a porous section (almost like suction through a porous wall). Secondly I am now considering a streamwise vortical instability (called a Gortler vortex) and am looking at the effect of varying curvature, such as you have on the underside of a wing."

Aerofoil: a cross section of an object designed to alter flow. Image courtesy of another Google search.

Me: "Do you know of any good, free resources, perhaps that you used, on Fluid Dynamics?"

J: "There aren’t that many free resources that I know of. Being a member of Imperial allows me access to plenty of papers and journals, which is invaluable. But other than that there isn’t much. If we want, say, a cross-section of a particular wing we can get this off Airbus but that is only because we are funded by them."

Me: "What would you say to someone starting their journey to a career in Fluid Dynamics? Are there any particular pitfalls or rewards to watch out for?"

J: "I’d encourage anyone starting out in Fluids, it’s very enjoyable and a really applicable part of maths to the real world. There are plenty of opportunities for jobs. However if you’d like to follow the academic route it is very competitive, there aren’t that many post doc. positions and you have to be prepared to travel around a bit to find them.
The work it self should be interesting, there are lots of areas in Fluids to study. Our laminar flow control study is interesting but also Micro Fluids, Biological Fluids, and Environmental Fluids have some really interesting applications. You may need to be prepared to do a lot of coding, and researchers for some reason love FORTRAN, and writing up in LaTeX but if you don’t mind that too much the maths can be a real joy."

Me: "I want to study Fluids..."

A Reservoir of Resources 

So this is the section where I point you to the places that you can learn about Fluid Dynamics. Regardless of what factor of Fluid Dynamics floats your flapper, you will need to know the core components.

Level 1 (HyperPhysics)

I like to start light where I can, HyperPhysics is light, Level 1 and has a good section about fluids: Fluids at HyperPhysics.

Fluids at HyperPhysics.

Level 2 (Fitzpatrick)

After Level 1 it's a big jump, The Fitzpatrick Physics Files post landed a reet good reservoir of resources at Level 2. Here's the ones on Fluid Dynamics: Fitzpatrick's Fluid Dynamics. These ones are really good.

Fitzpatrick's Fluid Dynamics (Mechanics).

Level 3 (ArXiv)

As Jamie mentioned he uses plenty of papers. For anyone that isn't a member of a university, the workaround is to use ArXiv. This landed in The ArXiv Repository post way back in April 2013. There is a section devoted to Fluid Dynamics on ArXiv: Fluid Dynamics at ArXiv.

Fluid Dynamics at ArXiv.

Coding

Jamie also disclosed that life will be easier if you know how to code. I am still a believer that C++ is the best starting place for coding - The Pasture of C++ Notes post.

That Bit at the End...

It's one of the most fascinating places to see physics and mathematics factify and formulate the universe around us. Hats off to Jamie Nutter. This was Fluid Dynamics: