TY - JOUR
T1 - Numerical Simulation of Scalar Mixing and Transport through a Fishing Net Panel
AU - Yang, Xinyue
AU - Gaultieri, Carlo
AU - Cuthbertson, Alan
AU - Wang, Ruo-Qian
AU - Shao, Dongdong
N1 - Funding Information:
This work was supported by the National Natural Science Foundation of China (Grant No. 51779012 and 51811530316), the National Key Research and Development Program of China (Grant No. 2018YFC1406404), and Interdisciplinary Research Funds of Beijing Normal University. The authors (DS, RQW and AC) are also grateful for financial support provided by The Royal Society through an International Exchange Cost Share (China) 2017 Grant (Grant No. IEC\NSFC\170104) which facilitated bilateral research visits between Beijing Normal University and the University of Dundee. Financial support for C. Gualtieri from the State Administration of Foreign Experts Affairs of China is also gratefully acknowledged.
Publisher Copyright:
© 2022 by the authors.
PY - 2022/10/17
Y1 - 2022/10/17
N2 - 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.
AB - 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.
KW - aquaculture
KW - computational fluid dynamics (CFD)
KW - mass transport
KW - near-field hydrodynamics
KW - net panels
KW - OpenFOAM
KW - plume concentration decay
KW - standard k-ε model
UR - http://www.scopus.com/inward/record.url?scp=85140972544&partnerID=8YFLogxK
U2 - 10.3390/jmse10101511
DO - 10.3390/jmse10101511
M3 - Article
VL - 10
JO - Journal of Hydro-environment Research
JF - Journal of Hydro-environment Research
SN - 1570-6443
IS - 10
M1 - 1511
ER -