Bottom bow radical - pictograph of an archery bow strung with its curve clearly visible. The bow is the prototypical curved object, so it indexes the 'bend, curve' meaning of 弯. Family: 张 (draw a bow), 强 (strong, originally a kind of bow), 引 (pull a bow), 弱 (weak).
Top 亦 supplies the sound for the simplified 弯 - yì drifted to wān. In the traditional 彎 the top was the more elaborate 䜌, which the 1956 reform replaced with 亦 to cut strokes. Same simplified-亦 phonetic in 蛮 (savage), 恋 (love), 湾 (bay).
