Mucus clearance by two-phase gas-liquid flow mechanism: asymmetric periodic flow model

1987 ◽  
Vol 62 (3) ◽  
pp. 959-971 ◽  
Author(s):  
C. S. Kim ◽  
A. J. Iglesias ◽  
M. A. Sackner
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Flow Model ◽  
Horizontal Tube ◽  
Tube Model ◽  
Flow Mechanism ◽  
Inspiratory Flow Rate ◽  
Two Phase ◽  
Mucus Clearance ◽  
Gas Liquid Flow

Mucus transport by two-phase gas-liquid flow mechanism was investigated with in vitro flow models under asymmetric periodic airflow conditions with nine different liquid solutions with rheological properties similar to human sputum. The flow model was made with 1.0-cm-ID glass tube and positioned either vertically or horizontally. With a constant supply of the test liquids into the model tube (0.5 ml/min), the liquid layer transport speed (LLTS) as well as the mean liquid layer thickness at steady-state condition (hs) was measured in conjunction with various airflow patterns of different expiratory and inspiratory flow rate, breathing frequency (f), and tidal volume (VT). The flow patterns were maintained within the range of normal breathing. In the horizontal tube model, LLTS ranged from 1.14 +/- 0.02 to 3.39 +/- 0.04 cm/min at the peak expiratory flow rate (VEp) of 30–60 l/min. The inspiratory flow rate, as well as f and VT did not affect LLTS. However, LLTS increased with increasing VEp, and at the same VEp LLTS was higher with viscoelastic than with viscous liquid. In the vertical tube model, the upward transport of mucus could not be achieved at VEp lower than 30 l/min particularly with low viscosity and low elasticity fluid. However, at high values of VEp, LLTS was comparable to that in the horizontal tube model with viscoelastic fluid, whereas LLTS of viscous liquid showed 26–40% lower than that in the horizontal tube model. The value of hs was 5–20% of the tube diameter at VEp of 30–60 l/min in both models. These results indicate that effective mucus clearance can be achieved by two-phase gas-liquid flow mechanism in patients with excessive bronchial secretions with biased tidal breathing favoring the expiratory flow and that the clearance can be further promoted by changing rheological properties of mucus.

Criteria for mucus transport in the airways by two-phase gas-liquid flow mechanism

1986 ◽  
Vol 60 (3) ◽  
pp. 901-907 ◽  
Author(s):  
C. S. Kim ◽  
C. R. Rodriguez ◽  
M. A. Eldridge ◽  
M. A. Sackner
Keyword(s):  
Layer Thickness ◽  
Liquid Layer ◽  
Liquid Flow ◽  
Critical Conditions ◽  
Airflow Rate ◽  
Tube Model ◽  
Flow Mechanism ◽  
Two Phase ◽  
Liquid Layer Thickness ◽  
Gas Liquid Flow

The critical conditions for mucous layer transport in the respiratory airways by two-phase gas-liquid flow mechanism were investigated by using 0.5- and 1.0-cm-ID tube models. Several test liquids with rheological properties comparable to human sputum were supplied continuously into the vertically positioned tube models in such a way that the liquid could form a uniform layer while traveling upward through the tube with a continuous upward airflow. The critical airflow rate and critical liquid layer thickness required for the upward transport of the liquids were determined. The critical airflow rate was in the Reynolds number (Re) range of 142–1,132 in the 0.5-cm-ID tube model and 708–2,830 in the 1.0-cm-ID tube model depending on the types of liquids tested. In both models, the critical airflow rate was lower with viscoelastic liquids than with viscous oils. The critical liquid layer thickness ranged from 0.2 to 0.5 mm in the 0.5-cm-ID tube model and 0.8 to 1.4 mm in the 1.0-cm-ID tube model at Re of 2,800. These values decreased rapidly with increasing airflow rate. The critical thickness relative to the tube diameter ranged from 3 to 15% of the respective tube diameter and was lower by approximately 30–50% in the 0.5-cm-ID tube model than in the 1.0-cm-ID tube model over the entire Re range tested. The results indicate that the critical conditions for the mucus transport by two-phase gas-liquid flow mechanism are within the range that can be achieved in patients with bronchial hypersecretions during normal breathing.

Determination of Entrained Fraction in Vertical Annular Gas/Liquid Flow

1999 ◽  
Vol 122 (1) ◽  
pp. 146-150 ◽  
Author(s):  
Barry J. Azzopardi ◽  
Sohail H. Zaidi
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Annular Flow ◽  
Flow Model ◽  
Liquid Flow Rate ◽  
Measured Concentration ◽  
Diameter Pipe ◽  
A New Technique ◽  
Gas Liquid Flow

A new technique for the measurement of drop concentration in annular gas/liquid flow is presented. This is based on scattering of light by the drops. From the measured concentration, entrained liquid flow rate and thence the entrained fraction can be determined. The technique has been employed to obtain new data for vertical upward annular flow in a 0.038 m diameter pipe. The results have been compared with data from different pipe diameters and with the predictions of an annular flow model. [S0098-2202(00)02201-X]

Simulated Mucus Clearance in Horizontal vs. Vertically Inclined Rigid Tracheal Model

2001 ◽  
Author(s):  
Cahit A. Evrensel ◽  
Halil R. Öz ◽  
Peter E. Krumpe ◽  
Amgad A. Hassan
Keyword(s):  
Liquid Flow ◽  
Mucociliary Clearance ◽  
Mucociliary Transport ◽  
Serous Fluid ◽  
Two Phase ◽  
Mucus Clearance ◽  
Gas Liquid Flow ◽  
Primary Basis ◽  
Conducting Airways ◽  
Serous Layer

Abstract Epithelia of conducting airways is lined with a layer of mucus above a layer of serous fluid. Mucus is a viscoelastic gel, while the serous layer is identified as “watery”. In normal airways, the mucociliary transport system forms the primary basis for clearance of mucus. Dehydration results in the disappearance of serous layer and impairs the mucociliary clearance. For these persons two-phase gas-liquid flow and cough become the dominant mechanisms.

Experimental Investigation of the Two-Phase Phenomena in a Small Discharge Installed on a Large Pipe With Stratified Gas-Liquid Flow

2009 ◽  
Author(s):  
Robert Bowden ◽  
Wael F. Saleh ◽  
Ibrahim Hassan
Keyword(s):  
Experimental Investigation ◽  
Flow Visualization ◽  
Flow Rate ◽  
Liquid Flow ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Gas Entrainment ◽  
Small Discharge ◽  
Gas Liquid Flow ◽  
Good Agreement

Experiments were performed in a 50.8 mm diameter horizontal pipe with co-current stratified gas-liquid flow. A single, 6.35 mm diameter, downward oriented discharge was located at 1829 mm from the horizontal pipe’s inlet. Water and air, operating at a pressure of 312 kPa and adiabatic conditions, were used. The objectives of the study were to investigate gas entrainment in the discharge branch. Qualitative flow visualization of the two-phase entrainment flow structure was conducted, and measurements of the critical liquid height, two-phase mass flow rate, and quality, are provided. The results were compared with available correlations and showed good agreement with selected models.

Co-Current Stratified Gas-Liquid Flow in a Horizontal Pipe With Discharging Branches

2009 ◽  
Author(s):  
Robert Bowden ◽  
Wael F. Saleh ◽  
Ibrahim Hassan
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Test Section ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Phase Measurements ◽  
Single Discharge ◽  
Gas Liquid Flow ◽  
Pipe Inlet ◽  
Two Fluid

Experiments were performed in an adiabatic horizontal pipe with co-current stratified gas-liquid flow and a single discharge oriented at either 0, 45, or 90 degrees from horizontal. The study used air and water as the two fluid phases, operating at 312 kPa. The test section was scaled down from a typical CANDU header-feeder bank and used a pipe and discharge diameter of 50.8 mm and 6.35 mm, respectively. The objectives of the study were to provide quantitative two-phase measurements of the mass flow rate and quality at the pipe inlet, outlet, and discharge branch.

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