For the laminar boundary layer, its thickness is expressed by the relationship (Where Rx is the local Reynolds number based on distance x from the leading edge)
1
δ = 0.664x / \(\rm R_{x}^{0.20}\)
2
δ = 0.664x /\(\rm \sqrt{R_x}\)
3
δ = 5x /\(\rm \sqrt{R_x}\)
4
δ = 1.75x / \(\rm \sqrt{R_x}\)