mill around
phrasal verb with mill verb [ T ] uk/mɪl/ us/mɪl/
(UK also mill about)
（一群人）无目的地乱转，闲荡
If a group of people mill around, they move around with no particular purpose or in no particular direction, sometimes while waiting for someone.
In the square, people were milling around in the sunshine. 在广场上，人们在阳光下徜徉。