Physics based EPQ format

Without having read any of the speifications, I would presume a dissertation is a library based project, based on research from existing literature, while the report is an lab based project, based on an experimental setup of your design and execution (with reference to existing literature to support the design of the experiment and analysis of the results).

Oh, thank you! Bit silly that I didn't realise that, but thank you for clarifying this for me.

I might end up doing a report then

There's a lot you can do experimentally with fluid mechanics as well, even with relatively basic supplies, so it's a fairly good option.

A library based thing would naturally be necessary for any kind of high energy or nuclear stuff as you're not exactly going to be able to do much with that practically!

Of course there's a lot of theoretical oriented things you can do with fluid mechanics (inc propulsion) as well, but this tends to be more on the maths side of things than physics.

Good luck though! It seems like a very good choice so hopefully should go well