Large eddy simulation of free-surface flows

McSherry, Richard; Chua, Ken; Stoesser, Thorsten

doi:10.1016/s1001-6058(16)60712-6

Cited by 36 publications

(21 citation statements)

References 73 publications

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“…Due to the lack of geometrical barriers in this region, this change has a smoother character. This is a consequence of the ability of the free surface of the liquid to undergo dynamic deformations under the influence of acting forces [14]. The overall axial flow direction is obtained after a contact is established with the free surface of the liquid.…”

Section: Resultsmentioning

confidence: 99%

Impact of stirrer rotational speed on liquid circulation in a rectangular vessel – a study applying DPIV

Ligus

Wasilewski

2018

E3S Web Conf.

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Abstract. This paper contains the results of experimental study concerned with liquid mixing process using a stirrer located in a rectangular vessel. The current study applied Digital Particle Image Velocimetry technique (DPIV). On the basis of non-invasive measurements, velocity vector profiles were determined with regard to the velocity of the mixing process, and they were subsequently applied for identification and assessment of liquid circulation in a vessel. The correlation between the rotational speed of the stirrer and fluctuations and directions of the liquid flow velocity were determined. This paper focuses on the assessment of the mixing intensity resulting from the rectangular geometry of the vessel. The study proposes and develops a dependence between the shape of the velocity profile of the circulating liquid and the intensity of the mixing process. The study demonstrates the existence of suitable conditions for performing mixing processes in rectangular vessels.

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Section: Resultsmentioning

confidence: 99%

Impact of stirrer rotational speed on liquid circulation in a rectangular vessel – a study applying DPIV

Ligus

Wasilewski

2018

E3S Web Conf.

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“…The free surface between liquid and air is simplified to an asymmetrical boundary using rigid-lid hypothesis, where the normal velocity and the gradient of the variables are set as zero. This hypothesis has been verified and is used in research about the open Chanel flows [41]. The pressure outlet boundary condition is used for the out boundary of the domain and the pressure is set as 1 bar.…”

Section: Geometry and Numerical Schemementioning

confidence: 95%

Numerical Investigation of a High-Pressure Submerged Jet Using a Cavitation Model Considering Effects of Shear Stress

Yang

Shi

et al. 2019

Processes

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In the current research, a high-pressure submerged cavitation jet is investigated numerically. A cavitation model is created considering the effect of shear stress on cavitation formation. As such, this model is developed to predict the cavitation jet, and then the numerical results are validated by high-speed photography experiment. The turbulence viscosity of the renormalization group (RNG) k-ε turbulence model is used to provide a flow field for the cavitation model. Furthermore, this model is modified using a filter-based density correction model (FBDCM). The characteristics of the convergent-divergent cavitation nozzle are investigated in detail using the current CFD simulation method. It is found that shear stress plays an important role in the cavitation formation in the high-pressure submerged jet. In the result predicted by the Zwart-Gerber-Belamri (ZGB) cavitation model, where critical static pressure is used for the threshold of cavitation inception, the cavitation bubble only appears at the nozzle outlet and the length of the cavity is much shorter than the actual length captured by the high-speed photography experiment. When the shear stress term is added to the critical pressure, the length of the predicted cavity is close to the experimental result and three phenomena of the jet are captured, namely, growth, shedding, and collapsing, which agrees well with the experimental high-speed image. According to the orthogonal analysis based on the simulation result, when the jet power is unchanged, the main geometry parameter of the divergent-convergent nozzle that affects the jet performance is the divergent angle. For the nozzle with three different divergent angles of 40°, 60°, and 80°, the one with the medium angle generates the most intensive cavitation cloud, while the small one shows the weakest cavitation performance. The obtained simulation result is confirmed by cavitation erosion tests of the Al1060 plate using these three nozzles.

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“…The application of Computational Fluid Dynamics (CFD) methods to study free surface flows is an interesting avenue where different flow features can be calculated in detail with the solution of the Navier-Stokes equations, where the Reynolds Averaged Navier-Stokes (RANS) framework is employed [11,12]. Further several recent studies in literature present eddy-resolving frameworks such as Kirkil et al [13], Kara et al [14], Kang and Sotiropoulos [15] and McSherry et al [16]. Eddy-resolving simulations provide a higher level of detail regarding the coherent structures in a turbulent flow and a better resolution of the flow compared to the RANS models [17].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Free Surface Turbulence Damping in RANS Simulations for Complex Free Surface Flows

Kamath

Fleit

Bihs

2019

Water

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The modelling of complex free surface flows over weirs and in the vicinity of bridge piers is presented in a numerical model emulating open channel flow based on the Reynolds Averaged Navier-Stokes (RANS) equations. The importance of handling the turbulence at the free surface in the case of different flow regimes using an immiscible two-phase RANS Computational Fluid Dynamics (CFD) model is demonstrated. The free surface restricts the length scales of turbulence and this is generally not accounted for in standard two-equation turbulence modelling approaches. With the two-phase flow approach, large-velocity gradients across the free surface due to the large difference in the density of the fluids can lead to over-production of turbulence. In this paper, turbulence at the free surface is restricted with an additional boundary condition for the turbulent dissipation. The resulting difference in the free surface features and the consequences for the solution of the flow problem is discussed for different flow conditions. The numerical results for the free surface and stream-wise velocity gradients are compared to experimental data to show that turbulence damping at the free surface provides a better representation of the flow features in all the flow regimes and especially in cases with rapidly varying flow conditions.

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Large eddy simulation of free-surface flows

Cited by 36 publications

References 73 publications

Impact of stirrer rotational speed on liquid circulation in a rectangular vessel – a study applying DPIV

Impact of stirrer rotational speed on liquid circulation in a rectangular vessel – a study applying DPIV

Numerical Investigation of a High-Pressure Submerged Jet Using a Cavitation Model Considering Effects of Shear Stress

Investigation of Free Surface Turbulence Damping in RANS Simulations for Complex Free Surface Flows

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