Air at 20°C flows at 1 m/s between two parallel flat plates spaced 5 cm apart. Estimate the distance from the entrance to the point at which the hydrodynamic boundary layers meet.
GIVEN
Air flows between two parallel flat plates
Air speed (U?) = 1 m/s
Distance between the plates (D) = 5 cm = 0.05 m
Air temperature = 20°C
FIND
The distance from the entrance (X1) where the boundary layers meet
ASSUMPTIONS
Steady state
Laminar flow
SKETCH
If the boundary layer is laminar, the hydrodynamic boundary layer thickness is given by Equation
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