3. Hydrodynamic Boundary Layer



Entry Length: \[\begin{aligned} \text{Laminar flow:} \qquad & \left(\frac{L}{D}\right)_{e,h} &\approx 0.05\; \text{Re} \\ \ & \text{Turbulent flow:} & \left(\frac{L}{D}\right)_{e,h} &> 10 \end{aligned}\]