Formation of added faces over the surface
 

Hi,

I am using unstructured grid to generate mesh for my 3D geometry. The 3d geometry is shown below. It has two fluid zones and it is drawn in design modular and export to icem for meshing.

After mesh is done , in the subset it showing added faces. the image is shown below.

What is reason for the formation of added faces?
Whether it affect the solution in fluent?

Thanks