Numerical Simulation of Fluid–Structure Interaction Problems with Applications to Flow in Vocal Folds - Fluid-Structure Interaction and Biomedical Applications - page 361

Fig. 5.18 Comparison of the flutter velocities computed by the FE method with the simplified
flow theory [ 39 - 41 ]
Fig. 5.19 Comparison of the subglottal pressures (phonation threshold pressures—PTP) com-
puted by the FE method with the simplified flow theory [ 39 - 41 ]
Simulation examples of the flow velocity distribution in the glottis during the
aeroelastic instability for V 0 D 1:5 ms 1 are shown in Figs. 5.21 , 5.22 at several
time instants marked in the graph of w 1 .t/ and w 2 .t/. The maximal flow velocities
in the channel are increasing when the glottal gap is becoming narrower, i.e., for
high values of w 2 .t/; the maximum flow velocity in the glottal gap is lower than
40 ms 1 , which is in agreement with reality. Small changes in the position of the
flow separation point on the vocal fold surface can be also detected in the flow field
patterns in the glottal gap (see, e.g., the details in Fig. 5.22 at the time t 4 and t 5 ).
Comparison of the Results with Simplified Theory
The results obtained by the developed numerical method based on the FE solution
of the 2D Navier-Stokes equations are compared with the results computed by the
perturbation theory for 1D potential flow model [ 40 ]inFigs. 5.18 , 5.19 ,and 5.20 .
The computed flutter airflow velocities V 0;flutter , the pressure drop p flutter ,i.e.,the
so-called phonation threshold pressures (PTP), and the flutter frequencies F 0 ,i.e.,