as i stood in front of 737 i saw this cowling chine and wonder of its purpose. so i dug internet and found those discussion from indonflyer dot net. since they discuss in indonesian it is relatively difficult to understand (although I'm Malaysian). guess need time to understand. here some pictures from indonflyer...
(translated)
at low speed nacelle generate it's own vortex (vortex started before chine)
p/s: this picture should be without chine to avoid confusion.
to overcome, chine placed. (vortex started from chine)
