Numerical investigation of the impact of computational resolution on shedding cavity structures

Asnaghi, Abolfazl; Feymark, Andreas; Bensow, Rickard

doi:10.1016/j.ijmultiphaseflow.2018.05.021

Cited by 42 publications

(11 citation statements)

References 56 publications

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“…More specifically, it was found that LES can offer a better performance in the prediction of the intermittent vortices compared with RANS. Thanks to the latest works of the research groups at the Swiss Federal Institute of Technology of Lausanne [25][26][27][28], the Technical University of Munich [29][30][31], the Chalmers University of Technology [32][33][34], the Delft University of Technology [35] and the University of London [36][37][38], great progress has been made in the simulation of cavitation in vortical flows with LES. These works have increased the understanding of the cavitation effects on vortices/eddies dynamic behavior, ranging from the large scales to the intermittent ones.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of the Cavitation Effects on the Vortex Shedding from a Hydrofoil with Blunt Trailing Edge

Chen

Geng

Escaler

2020

Fluids

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Vortex cavitation can appear in the wake flow of hydrofoils, inducing unwanted consequences such as vibrations or unstable behaviors in hydraulic machinery and systems. To investigate the cavitation effects on hydrofoil vortex shedding, a numerical investigation of the flow around a 2D NACA0009 with a blunt trailing edge at free caviation conditions and at two degrees of cavitation developments has been carried out by means of the Zwart cavitation model and the LES WALE turbulence model which permits predicting the laminar to turbulent transition of the boundary layers. To analyze the dynamic behavior of the vortex shedding process and the coherent structures, two identification methods based on the Eulerian and Lagrangian reference frames have been applied to the simulated unsteady flow field. It is found that the cavitation occurrence in the wake significantly changes the main vortex shedding characteristics including the morphology of the vortices, the vortex formation length, the effective height of the near wake flow and the shedding frequency. The numerical results predict that the circular shape of the vortices changes to an elliptical one and that the vortex shedding frequency is significantly increased under cavitation conditions. The main reason for the frequency increase seems to be the reduction in the transverse separation between the upper and lower rows of vortices induced by the increase in the vortex formation length.

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Section: Introductionmentioning

confidence: 99%

Numerical Investigation of the Cavitation Effects on the Vortex Shedding from a Hydrofoil with Blunt Trailing Edge

Chen

Geng

Escaler

2020

Fluids

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“…However, this instantaneous pressure peak is the consequence of the final collapse but it is not the pressure source driving the cavity collapse. Moreover, the appearance of this local pressure peak is considered by Bensow et al, [37] to be a spurious effect of the numerical calculation. In contrast, the P den and P load predicted using p are much lower because the p levels are significantly smaller than the p(t) ones.…”

Section: Appl Sci 2020 10 X For Peer Review 11 Of 23mentioning

confidence: 94%

Numerical Simulation of Cavitation Erosion Aggressiveness Induced by Unsteady Cloud Cavitation

et al. 2020

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A numerical investigation of the erosion aggressiveness of leading edge unsteady cloud cavitation based on the energy balance approach has been carried out to ascertain the main damaging mechanisms and the influence of the free stream flow velocity. A systematic approach has permitted the determination of the influence of several parameters on the spatial and temporal distribution of the erosion results comprising the selection of the cavitation model and the collapse driving pressure. In particular, the Zwart, Sauer and Kunz cavitation models have been compared as well as the use of instantaneous versus average pressure values. The numerical results have been compared against a series of experimental results obtained from pitting tests on copper and stainless steel specimens. Several cavitation erosion indicators have been defined and their accuracy to predict the experimental observations has been assessed and confirmed when using a material-dependent damaging threshold level. In summary, the use of the average pressure levels during a sufficient number of simulated shedding cycles combined with the Sauer cavitation model are the recommended parameters to achieve reliable results that reproduce the main erosion mechanisms found in cloud cavitation. Moreover, the proposed erosion indicators follow a power law as a function of the free stream flow velocity with exponents ranging from 3 to 5 depending on their definition.

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“…Accordingly, the vaporization constant is modified as where is the time scale of the mean flow used to normalize the velocity strain rate value (Asnaghi et al. 2018 a ). In this study, and are set to 10.…”

Section: Numerical Modelsmentioning

confidence: 99%

“…As a result, these mass transfer models cannot appropriately resolve the dynamics of small collapsing cavities, especially sparse clouds of bubbles (figure 1 b ). As an example, Asnaghi, Feymark & Bensow (2018 a ) observed that the rate of phase change from vapour to liquid is over-predicted for a shed cloud on the suction side of a hydrofoil, which leads to an early collapse of the cloud in numerical modelling. Ye & Li (2016) showed that the bubble growth rate can be greatly reduced if the bubble–bubble interaction and second-order derivative in the Rayleigh–Plesset equation are considered.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation and analysis of multi-scale cavitating flows

2021

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Numerical investigation of the impact of computational resolution on shedding cavity structures

Cited by 42 publications

References 56 publications

Numerical Investigation of the Cavitation Effects on the Vortex Shedding from a Hydrofoil with Blunt Trailing Edge

Numerical Investigation of the Cavitation Effects on the Vortex Shedding from a Hydrofoil with Blunt Trailing Edge

Numerical Simulation of Cavitation Erosion Aggressiveness Induced by Unsteady Cloud Cavitation

Numerical simulation and analysis of multi-scale cavitating flows

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