Colloquium on 21.04.2017.
Where: Building 45, Seminar room (Institute LSA)
Start: 1:00 pm
Dr. Jan Gräfe
(Leibniz Institute of Vegetable and Ornamental Crops (IGZ Großbeeren)
The boundary layer conductance of plant leaves – a refinement of the characteristic dimension parameter
The heat and mass exchange of plant leaves is partly determined by the convection through the leaf boundary layer, which is quantified by the boundary layer conductance. Standard equations for the boundary layer conductance from engineering science require a characteristic dimension to be specified. The characteristic dimension of a plant leaf under variable air flow direction or for a population of differently inclined leaves is a complicated function of the path length distribution function over the actual leaf shape and the flow regime (i.e. laminar or turbulent forced flow). It is shown for elliptical shapes, that the exact characteristic dimension is well approximated by the mean random path length. The mean random path length of any shape can be easily obtained from the area and the perimeter. These finding should improve the parameterisation of convective heat and mass transfer of plant leaves both in simulation models and in experimental studies.
