The 64/4 Rule

In a recent article we covered how we went about transferring to OpenFOAM from a commercial CFD software package.  After discussing this further with a colleague, another interesting bit of learning came up – the Pareto Principle, otherwise know as the 80/20 rule.

It’s a principle that can be found to be applicable in all sorts of places. In the world of CFD, we often find the bulk of our simulations (the 80%) use a limited set of the of the types of workflows available (the 20%).

Applying the 80/20 rule to the 20% gives what’s known as 64/4 rule…

Transferring to OpenFOAM – start with your key workflow

Changing a CFD process can be a daunting task and it can be difficult to know where to begin.  However, if 64/4 holds true in your CFD process, then there’s likely to be one type of simulation that accounts for the bulk of your workflow.

This one workflow should be the first candidate for migrating, as it will provide the most impactful change for your efforts.

Back when we shifted from commercial CFD to open source, we chose our optimisation workflow, which was essentially the same type of model we were running for general aero-development… steady-state RANS, open road, full-car.  As a result, when we were ready to make the switch, we had a large drop-off in commercial licensing costs as we had tackled the 64%.

Small change, big impact.