Shear-Layer Detection in Poststenotic Flow by Spectrum Analysis of Doppler Signals

[+] Author and Article Information
T. Tamura, A. Fronek

Department of AMES-Bioengineering, University of California, San Diego, La Jolla, CA 92093

J Biomech Eng 110(4), 320-325 (Nov 01, 1988) (6 pages) doi:10.1115/1.3108448 History: Received December 26, 1986; Revised August 26, 1988; Online June 12, 2009


Spectrum analysis of the Doppler signals was performed 0.5 tube diameters downstream from an axisymmetric constriction with an area reduction of 80 percent in steady flow at a jet Reynolds number of 2840. Both pulsed and continuous wave (CW) Doppler spectra showed significant reverse flow components in the separated flow. The pulsed Doppler spectra exhibited sudden changes when the sample volume crossed the shear layer between the center jet and the separated flow. A power spectrum equation was theoretically derived from continuity of flow to define the Doppler shift frequency for the shear layer velocity. The CW Doppler spectrum showed a minimum spectrum density at a frequency which equalled the shear layer Doppler shift frequency derived from the equation. The pulsed spectra exhibited the sudden changes at the same frequency as well.

Copyright © 1988 by ASME
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