Fluid Flow through the Vessels of Birch Wood

Abstract

The axial relative conductivity of birch wood measured using water and dry air was found to be 34 and 38%, respectively, of that calculated from microscopic measurements assuming the vessels to be unobstructed capillaries. This is a consequence of the resistance to flow of the scalariform perforation plates and the presence of some vessels which terminate within the samples. Gas flow analysis shows that about half the resistance to viscous flow occurs at the perforation plates and half in the lumina of the vessel elements. About one fifth of the vessels terminated within a sample 20 mm long, and these vessels contribute little to the conductivity of the wood.