High-Frequency Pulsatile Pipe Flows Encompassing All Flow Regimes

Gebreegziabher, Tadesse; Sparrow, E. M.; Abraham, John; Ayorinde, Emmanuel O.; Singh, Tej

doi:10.1080/10407782.2011.627794

Cited by 36 publications

(14 citation statements)

References 39 publications

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“…While Strouhal number was in range Sh = 0...1.67. This range is consistent with quasi-steady and low-frequency pulsating flows, which were successfully simulated with RANS models before [5]. Harmonic variations of velocity are shown on fig.…”

Section: Introductionsupporting

confidence: 64%

“…Navier Stokes and conservation equations were closed with combined turbulence model (k-omega SST [4]). This model was successfully implemented in the previous numerical study of pulsations in linear channel [5]. An adequacy of implemented model was verified by comparison with adopted experimental data [6] for steady flow in a bended channel.…”

Section: Introductionmentioning

confidence: 98%

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The technology of heat transfer enhancement in channels by means of flow pulsations

Tsynaeva

Nikitin

2016

MATEC Web Conf.

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Abstract. The rate and efficiency of curing of concrete can boost when used intense heat. The work is dedicated to the development and research of technologies of intensification of heat transfer in channels by pulsations. The study was conducted by means of numerical methods based on mass and momentum conservation equations (Navier-Stokes) with software Code Saturne. Verification of implemented methods and software was performed. The research of heat transfer enhancement for semicircleshaped channel exposed to low-frequency pulsations was performed. The pulsation frequency of the flow during the study was in a range of 0...10 Hz. A significant (up to 4 times) increase of turbulent kinetic energy with implementing pulsations was detected. Flow pulsations with frequency of 10 Hz results in 1.21 times increase of heat transfer coefficient.

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Section: Introductionsupporting

confidence: 64%

Section: Introductionmentioning

confidence: 98%

The technology of heat transfer enhancement in channels by means of flow pulsations

Tsynaeva

Nikitin

2016

MATEC Web Conf.

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“…For the simulations, four full cardiac cycles were simulated to ensure that periodic solutions would result. 1,9,21,50 The pulse duration was 0.9 s and time steps of 0.01 s were used in the calculations. The results were independent of the time step size.…”

Section: Blood Flow Measurements In Multi-patient Studymentioning

confidence: 99%

“…20,33,59,65 The prior research includes both numerical and clinical/experimental studies that have evolved from very simple geometries to more complex studies of flow through more realistic lumens including non-Newtonian viscosity effects. 1,16,21,23,24,28,35,50,51 These studies are important, not only for the relationship between flow and pressure within a diseased artery, but they also have implications for other transport process through arterial walls. 7,8,19,[30][31][32]64,77 Furthermore, the presence of plaque or arterial hardening changes the compliance of the vessel wall which also affects blood flow and pressure (aside from the influence of the occlusions).…”

Section: Introductionmentioning

confidence: 98%

Alterations of Blood Flow Through Arteries Following Atherectomy and the Impact on Pressure Variation and Velocity

Plourde

Vallez

Sun

et al. 2016

Cardiovasc Eng Tech

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Simulations were made of the pressure and velocity fields throughout an artery before and after removal of plaque using orbital atherectomy plus adjunctive balloon angioplasty or stenting. The calculations were carried out with an unsteady computational fluid dynamic solver that allows the fluid to naturally transition to turbulence. The results of the atherectomy procedure leads to an increased flow through the stenotic zone with a coincident decrease in pressure drop across the stenosis. The measured effect of atherectomy and adjunctive treatment showed decrease the systolic pressure drop by a factor of 2.3. Waveforms obtained from a measurements were input into a numerical simulation of blood flow through geometry obtained from medical imaging. From the numerical simulations, a detailed investigation of the sources of pressure loss was obtained. It is found that the major sources of pressure drop are related to the acceleration of blood through heavily occluded cross sections and the imperfect flow recovery downstream. This finding suggests that targeting only the most occluded parts of a stenosis would benefit the hemodynamics. The calculated change in systolic pressure drop through the lesion was a factor of 2.4, in excellent agreement with the measured improvement. The systolic and cardiac-cycle-average pressure results were compared with measurements made in a multi-patient study treated with orbital atherectomy and adjunctive treatment. The agreements between the measured and calculated systolic pressure drop before and after the treatment were within 3%. This excellent agreement adds further confidence to the results. This research demonstrates the use of orbital atherectomy to facilitate balloon expansion to restore blood flow and how pressure measurements can be utilized to optimize revascularization of occluded peripheral vessels.

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“…It was later developed by the present authors in a series of studies which extended its use to internal flows, flows with adverse pressure gradients in diffusers, and pulsating flows [21][22][23][24][25][26][27][28][29][30]. Both the SST method and the newly developed transitional method rely upon a control-volume solution method wherein conservation equations are developed at a multitude of elements which constitute the solution domain.…”

Section: Fluid Dynamic Modelmentioning

confidence: 99%

Turbulent and Transitional Modeling of Drag on Oceanographic Measurement Devices

Abraham

Gorman

Reseghetti

et al. 2012

Modelling and Simulation in Engineering

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164

241

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Computational fluid dynamic techniques have been applied to the determination of drag on oceanographic devices (expendable bathythermographs). Such devices, which are used to monitor changes in ocean heat content, provide information that is dependent on their drag coefficient. Inaccuracies in drag calculations can impact the estimation of ocean heating associated with global warming. Traditionally, ocean-heating information was based on experimental correlations which related the depth of the device to the fall time. The relation of time-depth is provided by a fall-rate equation (FRE). It is known that FRE depths are reasonably accurate for ocean environments that match the experiments from which the correlations were developed. For other situations, use of the FRE may lead to depth errors that preclude XBTs as accurate oceanographic devices. Here, a CFD approach has been taken which provides drag coefficients that are used to predict depths independent of an FRE.

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High-Frequency Pulsatile Pipe Flows Encompassing All Flow Regimes

Cited by 36 publications

References 39 publications

The technology of heat transfer enhancement in channels by means of flow pulsations

The technology of heat transfer enhancement in channels by means of flow pulsations

Alterations of Blood Flow Through Arteries Following Atherectomy and the Impact on Pressure Variation and Velocity

Turbulent and Transitional Modeling of Drag on Oceanographic Measurement Devices

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