Part 6/9:
A significant element of the Tesla turbine's efficiency lies in understanding the concept of the boundary layer. In fluid dynamics, a boundary layer forms on surfaces where fluid adheres and creates stationary layers. As the fluid moves, it exerts drag forces on subsequent layers—contributing to a velocity gradient where energy loss occurs.
To exploit this phenomenon, Tesla innovatively introduced additional parallel disks. This configuration created overlapping boundary layers that enhanced the shear effects within the narrow gaps, boosting torque without allowing the free flow of the fluid. The strategic reduction of the space between the disks to about 0.4 millimeters optimized this boundary layer interaction—further increasing the turbine's potential for efficiency.