I sit down with the thermodynamics and the fluid dynamics and my mind just floods. The equations pile on top of each other, every term pointing to three more I half remember, and I can't find a place to stand. It's not one hard idea; it's all of them at once, and I feel like I'm drowning in it.
More people experience this than they realize.
The thermodynamics and fluid dynamics simply overwhelm you.
If this sounds familiar, the Library can help you find the bigger picture.