During the 80’s and 90’s I was involved with quite a string of startups. Each one was an interesting story. Some folded, some split into pieces, some sold to bigger companies, and some changed directions several times. One of the more interesting ones just kept plugging away at their original vision. Today they reached a pretty exciting milestone. This morning my old friend Steve rang NASDAQ’s opening bell, and Exa is a publicly traded company!
Exa makes software for simulating fluid flow. That’s usually called CFD, which stands for Computational Fluid Dynamics. I did quite a bit of CFD in school. In fact my thesis was a simple CFD simulation of the underbody aerodynamics of a Formula 1 car. But the software we developed at Exa was wildly different from anything I’d seen before. It was originally developed by Kim Molvig at MIT. In some ways it’s similar to lattice gas, which is a cellular automata which simulates fluid flow by bouncing particles around on a grid. This is a lot different from the PDE approach used by most CFD solvers.
Although the traditional approach works well for airflow around very streamlined objects (like airplanes), it’s not so great with complex airflows. Exa’s approach is much better when things get really complicated. In the sort of separated, turbulent airflow you see around a car, for example, Exa’s PowerFLOW solver is hard to beat. I remember when we got the first results from separated flow around a car’s A-pillar and you could see that it was accurately predicting what the wind noise would sound like. That was just amazing.
I worked on a lot of interesting problems there. I wrote the first version of their visualization system, and I did a lot of work on the gridding system. But after we shipped the first couple of releases, I wandered off to start a new project (as I’m wont to do). Several of the other guys (in particular Steve Remondi and Hudong Chen) stuck with it. There were certainly some challenging times. It was probably pretty scary when the car industry cratered during the recession.
Exa was such a great group of people, they really deserve the success. Congratulations guys, great work!