Abstract:

The average percentage of tracheid volume is over 90% for softwoods species. Gas permeability of softwoods is in close relationship with the flow of gas through the tracheids. The thorough knowledge of the gas permeability of softwoods can be gained by the flow-resistor of tracheids for the flow of gas. Based on the structural model for tracheid, the expressions of flow-resistors of tracheid in three directions of grain are reduced with the theories of fluid mechanics. The gas permeability of tracheids also calculated from their flow-resistors in this paper. The calculation show that flow-resistor can depict the resistance distribution in tracheid and the differences in gas permeability in three directions of grain. The flow-resistor is a useful way of studying on the gas permeability of softwoods and it can reveal the flow nature of gas through wood at level of woody cells.

Key words: Tracheid, Flow-Resistor, Linear flow, Gas permeability of wood