A strange streamline close to the wall
 

Hi everybody
I want to plot streamline of secondary flow structures in a curved-duct that was simulated using OpenFOAM in a special cross section. I used the streamtracers tool in tecplot. However, the streamlinesclose to the inner and outer walls is strange! I don't know why, and I don't know how to report the secondary flow structures in my paper.
I will appreciate any answer that can help me!

https://imgurl.ir/uploads/y283453_ph...6_11-56-42.jpg

https://imgurl.ir/uploads/t505868_ph...5_16-15-40.jpg