The pressure-flow method: some fundamental concepts.
The pressure-flow method introduced by Warren and DuBois is a useful method for estimating velopharyngeal orifice area. However, this investigation shows that unless geometric similarity of subject and model exists, the value of the flow coefficient k used in the equation to estimate velopharyngeal orifice area cannot be established from model tests. Use of k = 0.65 is questioned as that value is typical of thin plate orifices, a geometry that is not a good representation of the velopharyngeal passage. Values of k from the literature and from steady state tests using a model similar to Warren's are presented to show the effect of various inlet shapes. The influence of inlet shape supports the conclusion that k may be significantly higher than 0.65, conceivably approaching values in the range of 0.9 to 0.97, depending on the orifice geometry.
Yates
C C
CC
School of Engineering, University of Pittsburgh, PA 15261.
McWilliams
B J
BJ
Vallino
L D
LD
D006801:Humans; D008954:Models, Biological; D010160:Palate, Soft / Q000033:anatomy & histology*; D010614:Pharynx / Q000033:anatomy & histology*; D011312:Pressure; D012123:Pulmonary Ventilation / Q000502:physiology*; D012212:Rheology