Transitional (Tracheobronchial or Mixed) Flow

Mixed flow.jpg

Mixture of laminar and turbulent

At the same volumetric flow rate (volume of flow / amount of time) linear flow velocity is lower in small airways because of greater cross-sectional area.


FIGURE 6-23 Fluid velocity, at a constant flow, varies inversely with the cross-sectional area of the tube. (Modified from Nave CR, Nave BC: Physics for the health sciences, ed 3, Philadelphia, 1985, WB Saunders.)


Velocity of a fluid moving through a tube at a constant flow varies inversely with the available cross-sectional area


Exhalation- laminar pattern in bronchioles changes to turbulent in large airways

Inspiration – reverse occurs - turbulence in large airways changes to laminar in bronchioles

flow patterns in tb tree.jpg