I tend to get a velocity profile on the wall(like airfoil or car) using UDF.but I find it's hard to search the adjacent point for a given point,if anybody kown about this area,please help.

I am unable to understand the concept of displacement thickness, momentum thickness in Boundary layer.Please help

Please can you explain the concept of displacement thickness in simple words

Please can you explain the concept of displacement thickness in simple words.reply

The defination of displacement thickness is :because the existence of boundary layer make the free stream-line "Off" the wall. the distance between the wall and the free stream-line called "displacement thickness "

How do you know I know?

you can calculate the displacement thickness as follow: delta_star=integral from 0 to h (1-desity*u/desity_far*u_far)dy

you can let h equal to delta.

The defination of momentum thickness is :because the existence of boundary layer make the loss of momentum rate.

momentum thickness :theta=integral from 0 to h ((desity*u)/(desity_far*u_far)*(1-u/u_far))dy