PULMONARY MASS AND HEAT TRANSPORT

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Five related projects concerning pulmonary mass and heat transport for diffusible (gases) and poorly diffusible (aerosols) contaminants will be examined by hardware experiments and applied mathematical analysis. The overall aim is to address aspects of pulmonary transport phenomena which are motivated by physiological and clinical contexts and rooted in basic fluid mechanics. Specifically the five topics are: I. An experimental investigation of volume-cycled oscillating flow in a rigid, airway bifurcation model: flow velocity measurements will be made using a two-component laser doppler anemometor. Application of this technology will provide new information on this complicated flow that will be used in II to interpret its significance for transport. Simultaneous pressure measurements will be made to characterize impedance information with detailed flow phenomena. II. A theoretical investigation of volume cycled oscillatory flow and transport in a curved tube. The effects of axial curvature, which induce lateral streaming motions will be isolated and examined with respect to velocity, pressure and concentration fields. The overall effective diffusivity, Deff, of this system will be determined and directly related to frequency, amplitude, molecular diffusivity and axial curvature. III. A theoretical investigation of volume-cycled oscillatory flow and mass transport in a flexible channel. A mathematical analysis of velocity and pressure fields for this flow condition will be carried out in order to determine how the lateral wall motions influence the detailed velocity components and, subsequently, the dispersive and streaming characteristics. The direct dependence of Deff on wall compliance will be sought. IV. An experimental investigation of volume-cycled oscillatory flow in a flexible channel. By modifying our previous channel experiments, we will study the deformation of dye streaks to analyze axial streaming. Streaming is both a measure of transport for poorly diffusible contaminants and a signature of the unsteady velocities which influence Deff. V. Droplet spreading and transport on liquid film. A theoretical analysis of how a liquid droplet (an aerosol) spreads on a thin liquid film (lung's lining) from surface tension effects. The induced flow fields in the droplet and film will strongly influence the transport of contained solutes (drugs, toxins) into the airway wall.