Transport Function1

SIAM uses one of six transport functions to compute the annualized transport capacity. The appropriate equation is selected from the drop down box labeled Transport Function. Results are very sensitive to the transport function selection so care should be taken when selecting this option. For more description of these functions see Chapter 17 as well as the technical reference manual.

Separate transport functions can also be applied for different grain classes by selecting Multiple Transport Functions by Grain Size from the Options menu item. When this is selected, the transport function dropdown box becomes a command button with the caption Multiple Transport Eqs. Clicking this button to accessed the multiple transport functions grid, as shown in the bottom figure.

This grid lists the 20 grain classes and their respective geometric mean particle diameter size. By clicking on a cell in the Transport Eq. Column, the user can access a drop down box which allows selection of a grain class specific transport equation. Once selected, all cells below the currently active cell populate with the same transport equation. 

Note:

The grain class specific transport equation feature should be used with caution. When two different transport functions are used to compute transport potential for adjacent grain classes a discontinuity is often introduced. This could result in such difficulties as a larger computed potential for the larger grain class or an unreasonable drop in transport potential from one grain class to another. If this option is selected, pay careful attention to the results for material around the size of the transport transition(s). A similar caution should also be observed when attributing different transport equations to different reaches. This will cause spatial rather than gradational discontinuities and should be approached with similar caution.