represents the advective water flow from the xylem toward the sites of
evaporation and back diffusion from the sites of evaporation into the
rest of the leaf including the xylem.
The Péclet number is proportional to the transpiration rate (E )
and the effective mixing length (L ) that water takes to move from
the veins to the sites of evaporation, and inversely proportional to the
molar density of water (C ; 5.56 x 10-4 mol
m-3) and the diffusivity of
H218O in water (D ; Eqn. 8)
(Farquhar et al. 1998;
Barbour & Farquhar 2000;
Barbour et al. 2000b;
Gan et al. 2003;
Barbour & Farquhar 2004;
Barbour 2007). The diffusivity of
H218O in water calculated according to
Cuntz et al. (2007).