The total heat transfer to a single wall film droplet is found from the following energy balance:
 | (6–186) |
is the heat conducted from the wall, as given by:
 | (6–187) |
where 
is the conductive heat transfer coefficient
and 
is the wall area covered by the particle. This term
is always included in the energy equation for wall particles.
In the non-flooded regime, 
is assumed
to be equal to the drop diameter. The wall contact area is computed
from 
.
The heat transferred from the gas to the film, 
, is given by:
 | (6–188) |
where 
is the area covered
by a wall particle, 
is the conservative
gas temperature at the particle position, and 
is the film heat
transfer coefficient.
This term is always included in the energy equation for wall particles.
For the non-flooded regime, 
and 
are computed
as:
 | (6–189) |
The Nusselt number used for the calculation of 
is computed
using the Ranz-Marshall correlation for a sphere:
 | (6–190) |
In the flooded regime, 
is set equal to the transfer coefficient
for energy computed by the flow solver.
Note: The energy transfer coefficient is only available for turbulent flows. A physics check is added to the tracker setup phase to make sure that you set the flow type to turbulent.
The average wall film temperature (that is, the temperature of all wall particles associated to a boundary vertex) is computed by using the particle vertex machinery, by adding up contributions of wall particles (particles that already exist and new particles that turn into wall particles). This is done as a postprocessing step after all particles have been tracked.
accounts for the energy that is removed from the
wall film particle, as it evaporates into the surrounding medium:
 | (6–191) |
is the latent heat of vaporization, 
is the rate of evaporation.
The mass transfer rate for a single droplet is computed using the Liquid Evaporation Model. For particles below the boiling point, the following relation is used:
 | (6–192) |
The transfer coefficient, 
, is defined as:
 | (6–193) |
The Sherwood number is calculated using the Ranz-Marshall correlation for a sphere as:
The mass transfer rate of a particle component, 
, into the
coupled Euler phase can be determined by considering species mass
balances on control surfaces on either side of the phase interface:
 | (6–194) |
is the mass fraction
of the particle component at the film surface, and 
is the surface diffusive mass flux.
The surface mass flux can be expressed in terms of a mass transfer
coefficient, 
, as:
 | (6–195) |
is the mass fraction of the volatile
particle component as obtained from the flow field solution. The transfer
coefficient, 
, is set equal to the transfer
coefficient for scalars as computed by the flow solver.
Inserting Equation 6–195 into Equation 6–194 and solving for 
, gives:
 | (6–196) |
For particles above the boiling point this relation is used:
 | (6–197) |
where 
and 
is given by Equation 6–187 and Equation 6–188 respectively. 
is computed in the same way as for regular
particles.