Overview
The Hotstart feature allows the sediment model to be initialized based on the model output from a previous simulation. The feature also allows the user to choose what type of information to utilize from the previous model simulation and what to ignore. There are three types of Sediment Hotstarts:
- Bed Gradations and Bed Elevations
- Bed Gradations Only
- Bed Elevations Only
Sediment concentrations are hotstart only if the hydraulics is also initialized with a Prior Solution no matter what Sediment Hotstart Type is selected.
Specifying the HotStart File
The Hotstart file is specified as part of the plan data in the Sediment Output Options of the Unsteady Flow Analysis editor.
Figure 1. Sediment Hotstart section within the Sediment Output Options editor.
Hotstart Variables
Bed Gradations
When hotstarting bed gradations, the following datasets are always to read in:
- Layer Fractions or if it does not exist the Cell Active Layer Grain Fractions
- Layer Thickness
- Layer Dry Density
Note that if the Layer Fractions dataset does NOT exist in the Hotstart file, then the program will try to read the Cell Active Layer Grain Fractions dataset. If the program cannot find any of the datasets, then the specific variable is not hortstart.
None of the variables are above are output by default and therefore need to be turned on when creating the Hotstart file.
Bed Elevations
When hotstarting bed elevations, the following datasets are read in:
- Subcell Initial Hydraulic Bed Elevations
- Subcell Hydraulic Bed Change
- Subcell Initial Bed Elevation
- Subcell Bed Change
- Subface Initial Bed Elevation
- Subface Bed Change
Sediment Concentrations
When hotstarting sediment concentrations, the following datasets are read in
- Cell Total-load Concentrations
Even though the option to read in the sediment concentrations is tied to whether the hydraulics is also hotstart, the sediment concentrations are read in from the sediment HotStart file at the sediment Hotstart date and time.