"蜿蜒缓慢流动" can be translated into English as "meander slowly" or "wind its way slowly".
"Meander slowly" directly conveys the idea of flowing in a winding, slow manner.
"Wind its way slowly" is a more vivid expression, emphasizing the twisting and turning path of the flow while also indicating its slow pace.
Both phrases are suitable depending on the context and the desired level of imagery.