This Demonstration shows the unsteady-state evaporation of a liquid in bulk of vapor in an infinite tube, as governed by the following equation:

,

with

, .

Here is the diffusion coefficient, is the time, is the mole fraction of compound in the gaseous phase, is the nondimensional media molar velocity, and is the vertical position in the tube.

The boundary conditions are

at ,

at .

The problem is solved here using a shooting technique.

R. B. Bird, W. E. Stewart, and E. N. Lightfoot, Transport Phenomena, 2nd ed., New York: John Wiley and Sons.

D. S. Sophianopoulos and P. G. Asteris, "Interpolation Based Numerical Procedure for Solving Two-Point Nonlinear Boundary Value Problems," International Journal of Nonlinear Sciences and Numerical Simulations, 5(1), 2004 pp. 67–78.