Take a Blog Reader to Work Day

At one time or another most of you, my loyal readership, have had questions about what the life of others is like, such as: "What would it be like to be Spiderman?" "What would it be like to be an astronaut and repair the Hubble telescope?" "What would it be like to be that guy who operates the wrecking ball?" (Ok, so maybe not everyone fantasizes about being an astronaut.) But many have probably wondered, What is the life of a Computational Fluid Dynamacist like? Well you're in luck because recently at work I've a had a little spare time to work on some promotional things that will soon be on our new website. And since they will be on our website, I can share them (unlike most of the stuff we do which can't be shared with anyone.) The cool stuff is at the end.

So here it is. Most of my day is spent staring at this:

If you aren't familiar with this, it's probably a good thing because it means you also don't think math jokes are funny and also have good social skills/personal hygiene. This is a Linux command prompt. Just imagine there were no pictures or buttons on your computer and you had to type everything you want your computer to do. As bad as it sounds, it actually makes life much easier.

First we get 3D models all tidied up and ready for simulation. Then, we setup programs that simulate air blowing over or through stuff. Could be a building, could be a person, but usually it's a car of some sort. Then we look at the results and tell people what they mean. After that we make graphs of things and look at pictures of the air to see what is going on. Usually we tweak their designs somehow to make them better and run them again. Then we start the process over again and keep going in this loop until someone says stop.

Most of our simulations are run on our big computing boxes at the office which are essentially 24 really fast computers all running together which is 1 tera-flop of power. 1 tera flop is 1 trillion calculations per second. Most of our simulations take about 10 hours to solve. The numbers get pretty incomprehensible pretty fast. To give an idea of where all this power is going, essentially what is happening is the computer is solving a system of equations. If anyone remembers their algebra, that is like solving:

x + 2 = y

y+1 = x

You have to solve both equations at the same time to get an answer. Each simulation has about 50 million data points and each data point has six equations. These are usually solved about 3000 times. Anyway, it's lots of really crazy math that the computers do for us.

Anyway, since that part is usually not very exciting for most people, here are some shots that are mostly just eye-candy, but still cool. This particular simulation took a week to run.

This shot is slices through the air of the air pressure around the car. (Usually we don't color it to look like fire, but it makes a cool picture)

This is a picture of the car's wake. It's the layer of air that separates negative pressure air from positive pressure. Negative pressure is usually bad because it's suction and slows the car down. The wing on top is colored by air speed moving over its surface.

This is a picture of the air as it hits the wing of the car with what are called streamlines. It basically shows where the air goes. The streamlines are colored by their speed. The big circles are what's called a vortex.

This is a video that's pretty cool in hi-def. It shows the wake of the car changing over time. There's lots of turbulence.