  During liquid evaporation, the temperature of the liquid determines the
saturated vapor pressure above it, which controls the evaporation rate and thus
determines the liquid temperature through latent heat. Therefore, the equations
for the vapor concentration in the atmosphere and for the temperature in the
liquid are coupled and must be solved in an iterative manner. In the present
paper, a combined field approach which unifies the coupled fields into one
single field and thus makes the iteration unnecessary is proposed. The present
work will be useful in scientific and industrial processes involving liquid
evaporation and may also have more general applications to coupled field
problems in which all the fields have the same governing equation.
