Idealized COAWST model cases for studying the comparison of physical to numerical mixing with different tracer advection schemes in estuarine environments
Dates
Publication Date
2019-10-08
Citation
Kalra, T.S., and Warner, J.C., 2019, Idealized COAWST model cases for studying the comparison of physical to numerical mixing with different tracer advection schemes in estuarine environments: U.S. Geological Survey data release, https://doi.org/10.5066/P90KDWTX.
Summary
The numerical simulation of estuarine dynamics requires accurate prediction for the transport of tracers such as temperature and salinity. All numerical models introduce two kinds of tracer mixing: 1) by parameterizing the tracer eddy diffusivity through turbulence models leading to a source of physical mixing and 2) discretization of the tracer advection term that leads to numerical mixing. Both physical and numerical mixing vary with the choice of horizontal advection schemes, grid resolution, and time step. We utilize the Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) model to study the mixing in the model by simulating four idealized cases with three different tracer advection schemes.
Summary
The numerical simulation of estuarine dynamics requires accurate prediction for the transport of tracers such as temperature and salinity. All numerical models introduce two kinds of tracer mixing: 1) by parameterizing the tracer eddy diffusivity through turbulence models leading to a source of physical mixing and 2) discretization of the tracer advection term that leads to numerical mixing. Both physical and numerical mixing vary with the choice of horizontal advection schemes, grid resolution, and time step. We utilize the Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) model to study the mixing in the model by simulating four idealized cases with three different tracer advection schemes.
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salt_estuary2d_firstinitial.png “Image showing the setup of the estuary test model.”
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Related External Resources
Type: Related Primary Publication
Kalra, T.S., Li, X., Warner, J.C., Geyer, W.R., and Wu, H., 2019, Comparison of physical to numerical mixing with different tracer advection schemes in estuarine environments: Journal of Marine Science and Engineering, v. 7, no. 10, https://doi.org/10.3390/jmse7100338.
The formulation of physical and numerical mixing terms in the model is verified in test cases: 1) wind induced mixed-layer deepening and 2) horizontal tracer patch propagation. The latter involves only physical mixing while the former only has numerical mixing associated with it. The verification of physical and numerical mixing terms is done by comparing the time and volume integrated total mixing that amounts to total tracer variance decay. Idealized test cases of horizontal tracer patch propagation, lock exchange problem and estuary test case are used to find the effect of utilizing three different tracer advection schemes on mixing terms. The three advection schemes used in this work include – the MPDATA, U3H and HSIMT. All these schemes have been formulated differently from each other while providing a higher order of accuracy than the first order upwind scheme. The test cases highlight the mixing properties of the advection schemes.
Preview Image
Image showing the setup of the estuary test model.