Spectral Decomposition of the Flow and Characterization of the Sound Signals through Stenoses with Different Levels of Severity

Figures

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  Figure 1. A sectional view of the flow domain. Flow is from left to right. The figure is out of scale, and the dimensions are in mm.

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  Figure 2. Experimental setup of Laser Doppler Anemometry (LDA) axial velocity measurements for a constricted pipe representing arterial stenosis.

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  Figure 3. Validation of computational fluid dynamics (CFD) results of 92% stenosis at Re = 1600 with the LDA measurements.

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  Figure 4. Mean Pressure on the arterial wall in the post-stenotic region.

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  Figure 5. Mean axial velocity at six different locations (1D to 6D) downstream of stenosis for all severity cases.

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  Figure 6. Pressure fluctuations on the arterial wall and root-mean-square (RMS) of pressure fluctuations on the middle cross-section of the flow domain showing the concentration and high-energy fluctuation through and downstream of the stenosis.

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  Figure 7. Point of maximum excitation in the post-stenotic region by analyzing (a) RMS of pressure fluctuations on the wall and (b) turbulent kinetic energy (TKE) on the stenosis centerline.

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  Figure 8. For all severity cases: (a) Sound pressure level (SPL) variation at different frequencies of acoustic pressure and (b) exponential increase in RMS of pressure fluctuations and mean axial velocity with an increase in stenosis severity.

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  Figure 9. Acoustic spatial-frequency map of the post-stenotic region for all severity cases.

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  Figure 10. For 87% stenosis: (a) frequency content of the flow, (b) isosurfaces of proper orthogonal decomposition (POD) mode 1 of RMS of acoustic pressure, (c) snapshot of high-energy fluctuations for different frequency ranges and the bandwidth of 1000–1400 Hz.