Shape Factor (Boundary-layer thickness)
Description
A shape factor is used in boundary layer flow to determine the nature of the flow.
The higher the value of H, the stronger the adverse pressure gradient. A high adverse pressure gradient can greatly reduce the Reynolds number at which transition into turbulence may occur.
Conventionally, H = 2.59 (Blasius boundary layer) is typical of laminar flows, while H = 1.3 – 1.4 is typical of turbulent flows.
Variables
| H | shape factor (dimensionless) |
| δ* | displacement thickness (m) |
| θ | momentum thickness (m) |