clear
瀏 centers on clarity and purity, especially of water. Its core idea is something clear and unclouded.
瀏 combines 氵 (water) with 劉, which likely contributes the sound. The water radical points to the meaning of clear water.
Water 氵 beside 劉: imagine a stream so clear you can see the details of the character 劉 reflected in it.
For リュウ, picture a clear stream where you can see a tiny dragon (竜, りゅう) swimming: 竜 -> リュウ, and the water is so clear you can see it perfectly.