Experimental study of flow and mass transport in the near-wake region of a rigid planar metal net panel

Zeng, Xianglai; Gualtieri, Carlo; Cuthbertson, Alan; Shao, Dongdong

doi:10.1016/j.aquaeng.2022.102267

Cited by 5 publications

(20 citation statements)

References 38 publications

(71 reference statements)

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“…which was assumed to be constant throughout the domain. Hence, while eddy viscosity was calculated using Equation ( 6), the eddy diffusivity was estimated using Equation (7), where the value of Sc t was calibrated against the near-field concentration measurements presented in Zeng et al [8].…”

Section: The Governing Equationsmentioning

confidence: 99%

“…Notably, a number of previous studies have developed empirical formulas for C d as a function of both net properties and flow characteristics and summarized by Klebert et al [2]. In this study, the values of C n for calibration cases were determined against corresponding experimental data in Zeng et al [8], and further compared with the empirical formula from Klebert et al [2].…”

Section: Porous Media Modelmentioning

confidence: 99%

“…This, in turn, can have significant impact on fish health and growth rate, as well as on the surrounding environmental water quality [4,5]. As a key component of the fish cage or pen, the fishing net panels have a highly porous structure that generate relatively complex wake flows, especially at scales close to the netting mesh sizes [6][7][8]. Understanding the near-field flow field and mass transport processes through an individual net panel is therefore a critical first step to the more complex study of larger-scale flows involving individual cage/pen structures or even groups of cages/pens.…”

Section: Introductionmentioning

confidence: 99%

“…More recently, Shao et al [7] combined PIV and planar laser induced fluorescence (PLIF) flow imaging techniques to investigate experimentally the associated scalar transport process in the near-field wake of a steady current through a flexible net panel, observing that the presence of the net slightly enhanced the lateral spreading of the tracer plume. Zeng et al [8] subsequently measured the corresponding flow field and associated scalar transport processes through a rigid planar metal net panel, finding that the rigid nets reduce flow blockage and increase the rate of concentration decay compared to flexible nets with a similar solidity. Notably, regarding the mass transport process through net structures, analogous studies on the scalar transport in grid-generated turbulence have been widely reported in the literature [12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

“…This modelling approach has also recently been applied successfully to investigate similar aquaculture-related hydrodynamics in culture tanks for Atlantic salmon [26]. Within the current numerical modelling study, we have used previous experimental data reported in Zeng et al [8] to calibrate and validate the model, which was then applied to undertake extended scenario modelling. It is anticipated that the results from the study may provide new modelling perspectives on both the flow field and mass transport processes in the near-wake region of cage-based aquaculture.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Simulation of Scalar Mixing and Transport through a Fishing Net Panel

Yang

Zeng

Gualtieri

et al. 2022

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With the rapid development of commercial aquaculture in recent decades, large numbers of submerged cages or pens are clustered in fish farms that are commonly located within inland lakes, reservoirs, and coastal embayments around the world. The submerged structures have significant influence on both the flow fields and mass transport processes in surrounding water bodies. While existing studies have concentrated mainly on the flow blockage effects produced by fish cages, the associated effect on near-field mass transport processes, important for pollution transport and dispersal, remains largely unclear. To address this knowledge gap, a CFD (computational fluid dynamics) model was established using OpenFOAM to investigate the wake characteristics and scalar transport processes through a fishing net panel, as representative of a key component of the fish cage or pen. In this model, the net panel was represented as porous media, and the finite volume method was applied to solve the governing flow equations with the standard k-ε model used for turbulence closure. Experimental data from previous studies were used to calibrate and validate the numerical model, which was applied to different scenarios over a range of net solidities and incoming flow velocities. Overall, the numerical model results demonstrated that porous media schematization could adequately reproduce the blocking effect from the net panel on the mean flow field, as well as the induced changes to scalar transport, with satisfactory accuracy. The flow velocity reduction across the net panel was found to strengthen with increasing net solidity and decreasing incoming velocity, while the scalar concentration decay tended to become enhanced when the incoming velocity was decreased. The lateral profile of the scalar concentration exhibited a self-similar Gaussian distribution with the spreading width of the plume reduced by increasing the incoming velocity. This lateral concentration distribution was minimally affected by the upstream scalar source location relative to the net panel, when adopting the current RANS and porous media modelling approach. The model results provide useful references for the assessment of the environmental impacts and carrying capacity of cage-based fish farming.

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Section: The Governing Equationsmentioning

confidence: 99%