1、The friction brings about boundary layer effect in the sides of slice section of headbox and makes the velocity of ejection pulp from the headbox uneven.
2、In order to minimize the boundary layer effects, the nozzles were made as short as possible.
3、The bump which is equal to the local boundary layer thickness in height can divert the boundary layer effectively. As a result, no obvious low total pressure zone is found at the outlet of the inlet;
