Suspended sediment and bed load transport can be modelled in the 2D network by selecting options in the QM Parameters Dialog when scheduling a run in the Schedule Hydraulic Run View:
Water quality for the 2D parts of the model is set up in much the same way as for the 1D side. See the Water Quality Simulations and Water Quality Model sections for further details.
The 1D and 2D engines first solve advection of the determinants and then perform the diffusion step.
The mass advective flow in each face between elements is given by the following equation:
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where: Fa = mass flow through the face due to advection (kg/s) Fm = volumetric flow through the face (m3/s) c_upwind = cl if volumetric flow goes from left to right element, cr otherwise (kg/m3) where: cl = determinant concentration in left element (kg/m3) cr = determinant concentration in right element (kg/m3) |
The diffusion flow is calculated in each face between elements using the following equation:
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where: Fd = mass flow through the face due to diffusion (kg/s) k = diffusion coefficients (m2/s) hl = water depth in left element (m) hr = water depth in right element (m) cl = determinant concentration in left element (kg/m3) cr = determinant concentration in right element (kg/m3) d = distance between element centroids (m) L = face length (m) |
For details of sediment calculations, see the 2D Sediment Transport Equations topic.
The available sources of pollutant in a 2D Zone are:
The steps to setting up a 2D Water Quality model are:
The pollutograph data is combined with the inflow coming from the above objects to set the net mass determinant flow in the 2D engine.
One diffusion coefficient can be set up per sediment fraction and per dissolved determinant.
If no diffusion coefficient is specified for a specific pollutant, the engine will only transport it. There will not be any diffusion.
Additional results are available when running a water quality simulation: