Forcing frequency effects on turbulence dynamics in pulsatile pipe flow

Zhong-yu, Cheng; Jelly, Thomas O.; Illingworth, Simon J.; Marušić, Ivan; Ooi, Andrew

doi:10.1016/j.ijheatfluidflow.2020.108538

Cited by 12 publications

(13 citation statements)

References 45 publications

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“…In periodically driven turbulence in shear flows, a meanfield theory has been used to analyze the resonance maxima of the Reynolds number [3,4]. Periodic forcing in other turbulent systems, for example, in the homogeneous isotropic turbulence [5][6][7][8], pipe flow [9][10][11][12], channel flow [13,14], Taylor-Couette flow [15,16], and Rayleigh-Bénard (RB) convection [17][18][19], is also shown to have highly nontrivial response properties.…”

mentioning

confidence: 99%

Periodically Modulated Thermal Convection

et al. 2020

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Many natural and industrial turbulent flows are subjected to time-dependent boundary conditions. Despite being ubiquitous, the influence of temporal modulations (with frequency f) on global transport properties has hardly been studied. Here, we perform numerical simulations of Rayleigh-Bénard convection with time periodic modulation in the temperature boundary condition and report how this modulation can lead to a significant heat flux (Nusselt number Nu) enhancement. Using the concept of Stokes thermal boundary layer, we can explain the onset frequency of the Nu enhancement and the optimal frequency at which Nu is maximal, and how they depend on the Rayleigh number Ra and Prandtl number Pr. From this, we construct a phase diagram in the 3D parameter space (f, Ra, Pr) and identify the following: (i) a regime where the modulation is too fast to affect Nu; (ii) a moderate modulation regime, where Nu increases with decreasing f, and (iii) slow modulation regime, where Nu decreases with further decreasing f. Our findings provide a framework to study other types of turbulent flows with timedependent forcing.

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confidence: 99%

Periodically Modulated Thermal Convection

et al. 2020

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“…OpenFOAM is a second-order accurate finite volume solver. It has been shown to be an accurate tool for direct numerical simulation of single-phase flows [4] and for Euler-Lagrange simulations of two-phase flows [3]. Additionally, the point-particle method is on good footing theoretically when the particle diameter is less than the Kolmogorov length scale (d p < η) [1].…”

Section: Numerical Schemesmentioning

confidence: 99%

Effect of Particle Volume Fraction on Turbulence in Pipes and Channels

Zahtila¹,

Chan²,

Ooi³

et al. 2020

Australasian Fluid Mechanics Conference (AFMC)

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It is well known that turbulent channel and pipe flows show subtle differences in flow statistics. Here we investigate the effect of particle loading on the turbulence in these two geometries. We perform direct numerical simulations of both turbulent channels and pipes at Re τ = 180 with St + = 100 particles. Particle volume fractions of Φ f = 2×10 −5 , 2×10 −6 are compared with unladen simulations. Mean flow and turbulence intensities as well as energy spectra are computed along with visual inspection of Q-criterion iso-surfaces. The findings show that in both pipes and channels turbulence intensity is reduced in the inner region but slightly increased in the outer region. The effect being more pronounced in channels, despite the a larger near-wall accumulation of particles in pipes. Spectral signature shows a shift of energy to longer wavelength and away from the wall.

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“…Since the seminal work of Reynolds 8 , significant efforts have been made to study the transition to turbulence in pulsatile flows 9 – 13 . The focus has been on the exploration of criteria for laminar, transitional, and turbulent flow in pulsatile flows from different perspectives including hydrodynamic stability 14 and instability 15 , pulsatility 16 , and turbulence dynamics 17 . All these studies were for pulsatile flows in pipes.…”

Section: Introductionmentioning

confidence: 99%

Volumetric lattice Boltzmann method for wall stresses of image-based pulsatile flows

Zhang

Gomez-Paz

Chen

et al. 2022

Sci Rep

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Image-based computational fluid dynamics (CFD) has become a new capability for determining wall stresses of pulsatile flows. However, a computational platform that directly connects image information to pulsatile wall stresses is lacking. Prevailing methods rely on manual crafting of a hodgepodge of multidisciplinary software packages, which is usually laborious and error-prone. We present a new computational platform, to compute wall stresses in image-based pulsatile flows using the volumetric lattice Boltzmann method (VLBM). The novelty includes: (1) a unique image processing to extract flow domain and local wall normality, (2) a seamless connection between image extraction and VLBM, (3) an en-route calculation of strain-rate tensor, and (4) GPU acceleration (not included here). We first generalize the streaming operation in the VLBM and then conduct application studies to demonstrate its reliability and applicability. A benchmark study is for laminar and turbulent pulsatile flows in an image-based pipe (Reynolds number: 10 to 5000). The computed pulsatile velocity and shear stress are in good agreements with Womersley's analytical solutions for laminar pulsatile flows and concurrent laboratory measurements for turbulent pulsatile flows. An application study is to quantify the pulsatile hemodynamics in image-based human vertebral and carotid arteries including velocity vector, pressure, and wall-shear stress. The computed velocity vector fields are in reasonably well agreement with MRA (magnetic resonance angiography) measured ones. This computational platform is good for image-based CFD with medical applications and pore-scale porous media flows in various natural and engineering systems.

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Forcing frequency effects on turbulence dynamics in pulsatile pipe flow

Cited by 12 publications

References 45 publications

Periodically Modulated Thermal Convection

Periodically Modulated Thermal Convection

Effect of Particle Volume Fraction on Turbulence in Pipes and Channels

Volumetric lattice Boltzmann method for wall stresses of image-based pulsatile flows

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