1to somersault; to tumble; to flip
2to rummage; to turn things over repeatedly
3(of water, waves, emotions etc) to churn; to surge; to seethe
Example
wǒ我de的nǎo hǎi脑海lǐ里bù tíng不停de地fān téng翻腾zhe着zhè ge这个wèn tí问题。
我的脑海里不停地翻腾着这个问题。
I constantly went over this problem in my mind.