Large–eddy simulation in a Sonolator high–pressure homogeniser

Bagkeris, Ioannis; Michael, Vipin; Prosser, Robert; Kowalski, Adam

doi:10.1016/j.ces.2019.115441

Cited by 4 publications

(9 citation statements)

References 60 publications

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“…For given k , ε ,

\overset{u_{1^{*}}^{2}}{true}

and the above assumptions about

\overset{κ_{1}}{true}

and σ 1 , Equation ) returns a spectrum shape which mimics the 1‐D spectra observed in our LES of a high‐pressure homogenizer 47 . This is achieved by redistributing energy from across the full spectrum to the wave numbers local to the vortex shedding frequency.…”

Section: Energy Spectrum—structure Function Model Based On Turbulencementioning

confidence: 52%

“…The authors in Reference 48 concluded that the deviations between the measured spectra and the model spectra are consistent with finite Reynolds number effects (with Re L ∼ 1000 − 3000). In the high‐pressure homogenizer study, 47 Re L was also moderate 50 ranging from ∼10 3 − 10 4 .…”

Section: Deviations From Homogeneous Isotropic Turbulencementioning

confidence: 93%

“…Our previous work on LES of a high‐pressure homogenizer 47 showed that the regions in the mixer associated with peak drop fragmentation stresses also exhibit strong turbulence anisotropy; 1‐D energy spectra highlight an amplification of energy in the energy‐containing range associated with vortex shedding. Kolmogorov's standard 2/3 scaling in the corresponding second‐order structure functions is thus masked by vortex shedding and the resulting structure functions exhibit slopes between 2/3 and 2 in the inertial subrange.…”

Section: Deviations From Homogeneous Isotropic Turbulencementioning

confidence: 96%

“…Figure 4 depicts 1‐D energy spectra extracted from our LES in a Sonolator high‐pressure homogenizer 47 and model spectra from Equation ). From Figure 4a it may seen that the model spectra describe qualitatively the amplitude and the mean wave number of the energy perturbation at the various locations.…”

Section: Energy Spectrum—structure Function Model Based On Turbulencementioning

confidence: 99%

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Modeling drop breakage using the full energy spectrum and a specific realization of turbulence anisotropy

et al. 2021

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The assumption of homogeneous isotropic turbulence when modeling drop breakage in industrially relevant geometries is questionable. We describe the development of an anisotropic breakage model, where the anisotropy is introduced via the inclusion of a perturbed turbulence spectrum. The selection of the perturbed spectrum is itself motivated by our previous large‐eddy simulations of high‐pressure homogenizers. The model redistributes energy from small to large scales, and assumes that the anisotropic part of the Reynolds stresses is confined to the energy‐containing range. The second‐order structure function arising from the perturbed spectrum is used in the standard framework of Coulaloglou and Tavlarides to calculate breakage frequency. While the base model exhibits non‐monotonic behavior (by predicting a maximum value for a certain drop size), the effect of anisotropy is shown to increase breakage frequency in length scales larger than this peak, thereby reducing non‐monotonicity. This effect is more pronounced for small turbulence Reynolds numbers.

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“…For given k , ε ,

\overset{u_{1^{*}}^{2}}{true}

and the above assumptions about

\overset{κ_{1}}{true}

Section: Energy Spectrum—structure Function Model Based On Turbulencementioning

confidence: 52%

Section: Deviations From Homogeneous Isotropic Turbulencementioning

confidence: 93%

Section: Deviations From Homogeneous Isotropic Turbulencementioning

confidence: 96%

Section: Energy Spectrum—structure Function Model Based On Turbulencementioning

confidence: 99%

See 2 more Smart Citations

Modeling drop breakage using the full energy spectrum and a specific realization of turbulence anisotropy

et al. 2021

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“…However, there is of yet no consensus on which of these that are most suitable for modelling industrially relevant breakup processes. Moreover, the turbulence found in high-pressure homogenizers, rotor-stators mixers and similar systems deviates substantially from the ideal isotropic, homogenous turbulence assumed in deriving these models [21][22][23].…”

Section: Introductionmentioning

confidence: 89%

Estimating Breakup Frequencies in Industrial Emulsification Devices: The Challenge of Inferring Local Frequencies from Global Methods

Håkansson

2021

Processes

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Experimental methods to study the breakup frequency in industrial devices are increasingly important. Since industrial production-scale devices are often inaccessible to single-drop experiments, breakup frequencies for these devices can only be studied with “global methods”; i.e., breakup frequency estimated from analyzing emulsification-experiment data. However, how much can be said about the local breakup frequencies (e.g., needed in modelling) from these global estimates? This question is discussed based on insights from a numerical validation procedure where set local frequencies are compared to global estimates. It is concluded that the global methods provide a valid estimate of local frequencies as long as the dissipation rate of turbulent kinetic energy is fairly homogenous throughout the device (although a residence-time-correction, suggested in this contribution, is needed as long as the flow is not uniform in the device). For the more realistic case of an inhomogeneous breakup frequency, the global estimate underestimates the local frequency (at the volume-averaged dissipation rate of turbulent kinetic energy). However, the relative error between local frequencies and global estimates is approximately constant when comparing between conditions. This suggest that the global methods are still valuable for studying how local breakup frequencies scale across operating conditions, geometries and fluid properties.

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Application of a drop breakage model using the full energy spectrum and a specific realisation of turbulence anisotropy

Bagkeris

Michael

Prosser

et al. 2021

Chemical Engineering Science

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Large–eddy simulation in a Sonolator high–pressure homogeniser

Cited by 4 publications

References 60 publications

Modeling drop breakage using the full energy spectrum and a specific realization of turbulence anisotropy

Modeling drop breakage using the full energy spectrum and a specific realization of turbulence anisotropy

Estimating Breakup Frequencies in Industrial Emulsification Devices: The Challenge of Inferring Local Frequencies from Global Methods

Application of a drop breakage model using the full energy spectrum and a specific realisation of turbulence anisotropy

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