Male type meandering VS. Female type meandering

There are two types of meandering shape.

One is so-called female type and the other is so-called male type.

We did field measurements on these two different types of meandering leach in the Kushiro River on this August.  

http://yasu-ab.blogspot.com/2010/08/blog-post_22.html

We conducted numerical calculation on these two places.First is the female type.

Location is the rectangle on the above picture,

Flow separation is observed over the point bar located at the inner bend of the curved channel.

Next is the male-type. 
.

Flow pattern is very different.


Why this happens?

This is what we have to think about!