The Lent Term Experiment: Week 7

Apologies, this is a day late again.

Firstly, my thoughts and prayers go to those who have been affected by the earthquake off the coast of Japan, and I wish them the very best in dealing with this huge disaster that has befallen them.

This week, I have been busy getting frustrated by Computational Fluid Dynamics, or rather, the excessive amount of time it takes to do it.

Expectations for computers have changed a lot over the last decade or so - in the early 2000's, it was pretty much expected that if you wanted to view a picture, you'd need to wait for a few minutes. Streaming movies? Don't even think about it.

Nowadays though, our expectation for computer response is that it should be instantaneous. If a website takes over a few seconds to load, people complain at it being slow. Think about that for a (slow) second.

How does this relate to CFD and frustration? Well, as it so happens, CFD is very slow. This is because simulating air, believe it or not, is actually pretty difficult and as such hogs an inordinate amount of computer time. We use local workstations with 24 Gb of RAM and the Intel High Performance Cluster in Swindon which has 384 Gb of RAM on tap, as well as the latest Xeon 64-bit processors, and yet our mesh generation still takes anywhere from 10 to 30 minutes, and a complete set of iterations to reach a solution anywhere from 3 to 5 hours.

This is mildly frustrating, because the meshing program we use is powerful, and thus by the inverse relationship governing how Powerful a program is versus how User Friendly it is, it is not particularly user friendly. For example, there is no undo button; if you mess something up, be prepared to either reload a previous save, or to travel in a roundabout way to fix your mistake.

Also, if you make a mistake in say, Excel, it will usually take a few seconds to fix (even without the use of an undo button). If you make a mistake here, it could be one which sends the computer into it's own little happy world of number crunching for a LONG TIME, and you as the user will be left stranded, staring at a non-responsive screen, for however long it takes. Clicking the wrong button can feel like writing a deliciously dirty text to your significant other, and then realising it's been sent to your mum.

Anyway...here is the week 7 graph.