Determination of secondary flow morphologies by wavelet analysis in a curved artery model with physiological inflow

Bulusu, Kartik V.; Hussain, Shadman; Plesniak, Michael W.

doi:10.1007/s00348-014-1832-3

Cited by 18 publications

(21 citation statements)

References 55 publications

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“…Even biological organisms contain curved 'pipes' which constitute, for instance, respiratory and vascular systems. In these cases the interest lies in understanding the influence that the vortical structures, formed due to the secondary flow, have on the circulation of fluid (Bulusu, Hussain & Plesniak 2014). In addition, the flow inside bent pipes is important for the research on hydrodynamic stability and transition to turbulence.…”

mentioning

confidence: 99%

Modal instability of the flow in a toroidal pipe

Canton

Schlatter

2016

J. Fluid Mech.

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The modal instability encountered by the incompressible flow inside a toroidal pipe is studied, for the first time, by means of linear stability analysis and direct numerical simulation (DNS). In addition to the unquestionable aesthetic appeal, the torus represents the smallest departure from the canonical straight pipe flow, at least for low curvatures. The flow is governed by only two parameters: the Reynolds number Re and the curvature of the torus δ, i.e. the ratio between pipe radius and torus radius. The absence of additional features, such as torsion in the case of a helical pipe, allows us to isolate the effect that the curvature has on the onset of the instability. Results show that the flow is linearly unstable for all curvatures investigated between 0.002 and unity, and undergoes a Hopf bifurcation at Re of about 4000. The bifurcation is followed by the onset of a periodic regime, characterised by travelling waves with wavelength O(1) pipe diameters. The neutral curve associated with the instability is traced in parameter space by means of a novel continuation algorithm. Tracking the bifurcation provides a complete description of the modal onset of instability as a function of the two governing parameters, and allows a precise calculation of the critical values of Re and δ. Several different modes are found, with differing properties and eigenfunction shapes. Some eigenmodes are observed to belong to groups with a set of common characteristics, deemed 'families', while others appear as 'isolated'. Comparison with nonlinear DNS shows excellent agreement, confirming every aspect of the linear analysis, its accuracy, and proving its significance for the nonlinear flow. Experimental data from the literature are also shown to be in considerable agreement with the present results.

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mentioning

confidence: 99%

Modal instability of the flow in a toroidal pipe

Canton

Schlatter

2016

J. Fluid Mech.

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“…The combination of the two stent configurations when implanted in the test section, as shown in Figure 1d, embodied an idealized Type IV fractured stent following the classifications of Jaff et al [36] and Popma et al [31]. Our previous publications, Glenn et al [22], Bulusu and Plesniak [13] and Bulusu et al [23], can be referenced for further details on our experimental conditions, wherein we reported the PIV post-processing routines, the final window size and overlap, the pulse delays, the number of image pairs acquired toward phase-averaging and statistical convergence, the dynamic spatial range (DSR) and the dynamic velocity range (DVR) that varies with discrete instances of time in the pulsatile inflow waveform. The above information is summarized in Table 1 for succinctness.…”

Section: Stent Geometry and The Idealized Type IV Stent Fracturementioning

confidence: 99%

“…The details of the implementation of the CWT algorithm, the idea of Shannon entropy as a measure of the optimum scale of the wavelet basis function and several results of two-dimensional vortical patterns have been reported in Bulusu and Plesniak [13] and Bulusu et al [23]. A brief mathematical discussion is presented in the Section 4, to convey our use of Shannon entropy and its application to data filtering, compression and deconvolution.…”

Section: Continuous Wavelet Transform Using the Ricker Waveletmentioning

confidence: 99%

“…The belief that vortical flows and vortex-induced phenomena in the blood flows have a role to play in the proliferation of several cardiovascular diseases, such as atherosclerosis, carotid atheromatous disease, thoracic aortic aneurysms etc., has been discussed by Glenn et al [22], Bulusu et al [13,23], and several references cited therein. A common treatment for atherosclerosis is the opening of narrowed arteries resulting from obstructive lesions by angioplasty and stent implantation to restore unrestricted blood flow.…”

Section: Introductionmentioning

confidence: 99%

“…These secondary flow structures have been referred to deformed Dean-, Lyne-and Wall-type (D-L-W) secondary flow structure morphologies, which have the potential to affect wall shear stresses, which has been known to proliferate cardiovascular diseases, such as atherosclerosis [13,22,23,29].…”

Section: Application Of Secondary Flow Structure Detection In the Curmentioning

confidence: 99%

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Shannon Entropy-Based Wavelet Transform Method for Autonomous Coherent Structure Identification in Fluid Flow Field Data

Bulusu

Plesniak

2015

Entropy

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Abstract:The coherent secondary flow structures (i.e., swirling motions) in a curved artery model possess a variety of spatio-temporal morphologies and can be encoded over an infinitely-wide range of wavelet scales. Wavelet analysis was applied to the following vorticity fields: (i) a numerically-generated system of Oseen-type vortices for which the theoretical solution is known, used for bench marking and evaluation of the technique; and (ii) experimental two-dimensional, particle image velocimetry data. The mother wavelet, a two-dimensional Ricker wavelet, can be dilated to infinitely large or infinitesimally small scales. We approached the problem of coherent structure detection by means of continuous wavelet transform (CWT) and decomposition (or Shannon) entropy. The main conclusion of this study is that the encoding of coherent secondary flow structures can be achieved by an optimal number of binary digits (or bits) corresponding to an optimal wavelet scale. The optimal wavelet-scale search was driven by a decomposition entropy-based algorithmic approach and led to a threshold-free coherent structure detection method. The method presented in this paper was successfully utilized in the detection of secondary flow structures in three clinically-relevant blood flow scenarios involving the curved artery model under a carotid artery-inspired, pulsatile inflow condition. These scenarios were: (i) a clean curved artery; (ii) stent-implanted curved artery; and (iii) an idealized Type IV stent fracture within the curved artery.Entropy 2015, 17 6618

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On Stability and Transition in Bent Pipes

Canton

Schlatter

2019

Direct and Large-Eddy Simulation XI

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Determination of secondary flow morphologies by wavelet analysis in a curved artery model with physiological inflow

Cited by 18 publications

References 55 publications

Modal instability of the flow in a toroidal pipe

Modal instability of the flow in a toroidal pipe

Shannon Entropy-Based Wavelet Transform Method for Autonomous Coherent Structure Identification in Fluid Flow Field Data

On Stability and Transition in Bent Pipes

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