The form for Jet/Plume boundary condition (Figure 1) features the Current Boundary Cell and Boundary Group Conditions frames similar to the Flow Boundary Conditions form. Although in Current Boundary Cell for Jet/Plume, the user must define an upstream cell and a downstream cell simultaneously. In the Jet/Plume Type drop-down menu the user specifies the flow data of a jet plume boundary to link to with the time series options. These options include by-passing (ICAL=0), using a flow time series (QSER, ICAL=1), using a withdrawal return time series (W/R, ICAL=2). The Flow Series and W/R Series in Flow Assignment for Cell is enabled according to the Jet/Plume type selected.
In the Entrainment Opt menu the user sets whether to use the maximum of shear and forced entrainment or to use the sum of shear and forced entrainment.
The Entrainment Stop menu provides three options for stopping the entrainment: stop at a specified number of elements (ISTJP=0), stop when the center-line penetrates the bottom of the surface (ISTJP=1), or stop when the boundary penetrates the bottom of the surface (ISTJP=2).
Other options include setting the Entrainment Error Criteria, which is a factor used in the iterative solution. An adjustment factor for the Froude Number may also be set. The user may also specify the frequency, in the number of time steps, to update the jet/plume calculations.
In the Diffuser Port Settings frame the user may specify the settings for each discharge cell including the number of ports, the elevation, and the diameters of the port outlets, as well as the horizontal (azimuth) and vertical (altitude) angles. It should be noted that the flow in the QSER file is multiplied times the number of ports for the total flow for that BC cell. So for example, if a user has 10 ports with each port having a time series of 0.15 cms assigned for the jet, then the total flow is 10 * 0.15 cms = 1.5 cms.
The Maximum Number of Elements is mainly for plume compute termination if the plume calculation does not converge or reach the selected stop growth option. It is also important not to set this value too small before the plume reaches the stop growth option.
The Maximum Number of Iterations is the maximum number of loops to calculate within each step of the element computation. Since there is multiple loops to in the jet/plume computation, the actual computation can be time consuming. Therefore, Number of Time Steps for Update let users to define after how many hydrodynamic time steps, should EFDC+ compute the jet/plume result again and update the results. If simulate in a uniform flow condition, the number of time steps for update can be set much greater than a complex everchanging environment.
In theCalculation Optionmenu the user can select the Use Max of Shear or Forced option or Use Sum of Shear & Forced.
An adjustment factor for the Froude Number may also be set.
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Figure 1. Jet /Plume Boundary Condition form.
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