In an experiment a flat plate made from naphthalene is exposed to a parallel flow of pure air at a pressure of 1 bar. The air velocity away from the plate is 10 m/s. The air and plate are all at 300 K...

In an experiment a flat plate made from naphthalene is exposed to a parallel flow of pure air at a pressure of 1 bar. The air velocity away from the plate is 10 m/s. The air and plate are all at 300 K temperature. The experiment has been under way for 3 h.

(a) Calculate the reduction in the thickness of the naphthalene plate at 5 and 50 cm downstream from the leading edge of the plate

(b) Repeat part (a), this time assuming that the air velocity is 20 m/s.

Neglect viscous dissipation. For naphthalene vapor in air under atmospheric pressure, Sc = 2.35 at 300 K (Cho et al., 1992; Mills, 2001). Furthermore, the vapor pressure of naphthalene can be estimated from (Mills, 2001)

P_v
(T) = 3.631 × 10¹³
exp(−8586/T),

where T is in Kelvins and P_V
is in pascals