NUMERICAL INVESTIGATION OF AIR PERMEABILITY IN FIBERS WITH BIRD FEATHER-LIKE ARRANGEMENTS

摘要

Contour feathers in birds are of the two plumulaceous and pennaceous parts. Structural differences between these two sections of feathers underlie differences in their heat transfer and air permeation behaviors. The objective of the present study is to investigate air permeability in such structures. The insight thus gained will be useful for the manufacturing both clothing fabrics and heat insulators. The article begins with fiber simulation aimed at developing a structure similar to bird plumage. The results of numerical simulation are then validated against experimental results obtained for ostrich and magpie plumulaceous feathers. In a second stage, the effects of fiber diameter, fiber volume fraction, angle of rachis relative to bird skin, barb-rachis angle, and barbule-barb angle on permeability are investigated to derive a mathematical relation for estimating permeability coefficients for feather-like fibers. Results indicate that permeability in bird contour feathers increases with increasing distance from bird skin toward the feather tip. From among the parameters investigated, fiber diameter and volume fraction are found to have the greatest effects on permeability, whereas barb-barbule angle has the least.