Boundary layer conductance of the leaves of some tropical timber trees

摘要

AbstractThe boundary layer conductance of brass models of leaves exposed in a wind tunnel was determined from their cooling characteristics. Conductances were generally very low, as expected from large leaves. Nusselt numbers were calculated from the rates of heat loss, so that the results could be compared with established theory. There was generally good agreement between observed and calculated values. Leaves with veins displayed an apparent transition from a laminar to a turbulent boundary layer, and so did leaves inclined at an angle from the horizontal. In still air the observed rates of heat loss by natural convection were substantially higher than those calculated.