Cooling P9/5 shape

Good morning!

I am designing a transformer and my aim is to make it for a mobile charger, so it must be something small, but I wish I could get a high power, so I will have a high power density as well.

Testing to design it I've seen that a small core I could use is a P9/5, but it has a space in the center that does not interest me. So what I thought was taking advantage of that gap and I don’t know if what I've been thingking is okay. Could you use that space for cooling using liquid cooling or and air flow?

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