COMPUTATIONAL FLUID DYNAMICS

CFD

If my work is about post harvest storage, and managing temperatures and air flow in sugar beet clamps, Computational Fluid Dynamics (CFD) might just be the secret sauce. In the course I took, CFD was defined in the first lecture as: “approximate solution of governing equations using numerical techniques“. Looking back at the end of the course, this is a really good definition, but also one that wouldn’t mean much to an outsider. So put another way, CFD is the method engineers use to model systems that have gases and liquids – i.e. fluids – flowing through them, so as to understand how velocity, pressure, temperature, etc behaves within the system. They are models (so only approximate) based on mechanisms defined by laws of physics (the governing equations) using the simplified versions of these governing equations (numerical techniques).

Getting to know these methods (it’s really a compilation of many methods) has meant going back to some physics and mathematical concepts I thought were well in my past. It’s been hard work, but it has been so rewarding.

The below is an analysis I did in about 30 minutes purely for the purposes of showing the people I talk with about CFD how it can be used. What you’re looking at is a sugar beet clamp of 9m width, 3m height, being subjected to a 5m/s wind. Well, you’re actually seeing the air space 15m to the left, 25m to the right, and 15m above the ground a clamp is sitting on. The wind is blowing left to right, with the green area showing wind at 5m/s. The clamp clearly acts as a wind-break: the blue behind the clamp is wind at around 1m/s. The red area is wind of around 8m/s, so the clamp also causes an area of increased wind velocity. This all feels like it’s inline with expectations…