For uniform laminar flow(in the x-direction) past a flat plate at high Reynolds number, the local boundary layer thickness ($\delta$) varies with the distance along the plate (x) as

- $\delta$ $\propto$ x$^{1/4}$
- $\delta$ $\propto$ x$^{1/3}$
- $\delta$ $\propto$ x$^{1/2}$
- $\delta$ $\propto$ x