Spectral and Temporal Characteristics of Post-Stenotic Turbulent Wall Pressure Fluctuations

Abstract

The power spectral density of turbulent wall pressure fluctuations was measured in a tube downstream of a model arterial constriction. The flow parameters were varied from steady flow to conditions simulating human arterial pulsatile flow. Within the experimental uncertainty (±10 percent in characteristic turbulent frequency, fo, and ±25 percent in absolute rms pressure fluctuation amplitude), turbulent flow at the peak of systole produces wall pressure fluctuations identical to those of a steady flow at the same Reynolds number.

Acoustic radiation from a fluid-filled, subsurface vascular tube with internal turbulent flow due to a constriction

“…In this context, there have been numerous studies reported in the literature for more than three decades that have empirically and stochastically correlated sonic acoustic "signatures" with associated pathology. [5][6][7][8][9][10][11][12][13][14][15][16][17] A common observation in these studies is that sound intensity tends to increase with stenosis severity ͑until occlusion becomes nearly total͒, especially at audible frequencies on the order of hundreds of hertz ͑ϳ100 to 1000 Hz͒, and that this sound is associated with turbulence in the stenosed vessel distal to the constriction. Some have sought to put this into a diagnostic "imaging" format via use of a two-dimensional array of acoustic transducers mounted on the skin surface that can be used to passively beamform on the sonic source.…”

“…Numerous empirical and semiempirical models have been proposed to correlate measurements of the turbulent pressure field downstream of the occlusion with the geometry of the occluded vessel and the flow rate. 5,[8][9][10][11][12]16 Note that, even for relatively simple geometries, an exact solution using computational fluid dynamic ͑CFD͒ simulations is as of yet unavailable for the case of transitional fluid behavior and compliant vessel wall dynamics. Accurate CFD simulations for transitional flow problems with anatomically correct, yet assumed rigid vessel walls require substantial CPU time and are just now being reported.…”

Perineal noise recording as a non‐invasive diagnostic method of urinary bladder outlet obstruction: a study in polyvinyl alcohol and silicone model urethras

“…Another decade later, experimental [Koiso et al, 1991;Teri˛, 1991] and clinical studies [Koiso et al, 1991;van Koeveringe and van Mastrigt, 1991] were published on the relation between noise recordings and bladder outlet obstruction. In the same period of time, studies were done on vascular murmurs caused by stenoses, a method referred to as phonoangiography [Lees and Forbes Dewey, 1970;Duncan et al, 1975;Tobin and Chang, 1976;Fredberg, 1977;Pitts and Forbes Dewey, 1979;Jones and Fronek, 1987]. It was shown that based on either the mean power frequency [Teri˛, 1991], the break frequency of the noise spectrum [Tobin and Chang, 1976;Fredberg, 1977;Jones and Fronek, 1987], the shape of the recorded noise signal [Koiso et al, 1991], or a combination of the average power amplitude in a speci¢c frequency band with the simultaneously measured £ow rate [van Koeveringe and van Mastrigt, 1991] diagnosing arterial stenosis and bladder outlet obstruction could be possible.…”

Beamformed nearfield imaging of a simulated coronary artery containing a stenosis

“…5. This blockage was chosen because it has a 50% diameter reduction (or a 75% area reduction), which is similar to the reduction used by other researchers who have measured break frequencies [17], velocity [18]- [20], and pressure [4], [21], [22] caused by a constriction in a cylindrical tube. Moreover, this degree of blockage would be typical of presymptomatic CAD.…”