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Coupled Systems Mechanics   Volume 7, Number 1, February 2018, pages 95-109
DOI: http://dx.doi.org/10.12989/csm.2018.7.1.095
 
The relevance of turbulent mixing in estuarine numerical models for two-layer shallow water flow
Nino Krvavica, Ivica Kozar and Nevenka Ozanic

 
Abstract     [Full Text]
    The relevance of turbulent mixing in estuarine numerical models for stratified two-layer shallow water flows is analysed in this paper. A one-dimensional numerical model was developed for this purpose by extending an immiscible two-layer model with an additional source term, which accounts for turbulent mixing effects, namely the entrainment of fluid from the lower to the upper layer. The entrainment rate is quantified by an empirical equation as a function of the bulk Richardson number. A finite volume method based on an approximated Roe solver was used to solve the governing coupled system of partial differential equations. A comparison of numerical results with and without entrainment is presented to illustrate the influence of entrainment on both the salt-water intrusion length and lower layer dynamics. Furthermore, one example is given to demonstrate how entrainment terms may help to stabilize the numerical scheme and prevent a possible loss of hyperbolicity. Finally, the model with entrainment is validated by comparing the numerical results to field measurements.
 
Key Words
    turbulent mixing; entrainment; two-layer flow; finite volume method; shallow water flow; numerical model; estuaries
 
Address
Nino Krvavica and Nevenka Ozanic: Department of Hydrology and Hydraulic Engineering, Faculty of Civil Engineering, University of Rijeka, Radmile Matejcic 3, 51000 Rijeka, Croatia
Ivica Kozar: Department of Computer Modeling, Faculty of Civil Engineering, University of Rijeka, Radmile Matejcic 3, 51000 Rijeka, Croatia
 

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