Engine oil at 100°C flows over and parallel to a flat surface at a velocity of 3 m/s. Calculate the thickness of the hydrodynamic boundary layer at a distance 0.3 m from the leading edge of the surface.

Question

GIVEN

Engine oil flows over a flat surface

Engine oil temperature (Tb) = 100°C

Engine oil velocity (U) = 3 m/s

FIND

The hydrodynamic boundary layer thickness (?) at a distance 0.3 m from the leading edge

ASSUMPTIONS

Steady state

SKETCH



PROPERTIES AND CONSTANTS

From Appendix 2, Table 17, for engine oil at 100°C

Kinematic viscosity (v) = 20.3 ? 10–6 m2/s

Answer 1

The local Reynolds 0.3 m from the leading edge based on the bulk fluid temperature is



Since



the boundary layer is laminar. The boundary layer thickness for laminar flow over a flat plate is given by Equation (5.28)