tiny stream, swirl around, eddy
瀠 centers on water moving in a small, circular way: a tiny stream that swirls and forms eddies.
瀠 combines 氵 (water) with 縈, which likely contributes both sound and the idea of winding or coiling, suggesting swirling water.
Water 氵 on the left, and on the right a shape that looks like threads 糸 being wound around something under a cover 冖. Picture a tiny stream swirling threads into a tight eddy.
For エイ, imagine a tiny swirling stream shaped like the letter A: A -> エイ, and the water eddies around it.