18.15 2006-06 Release

Table 18.14 outlines the changes made to the default settings for the 2006-06 release and lists commands to revert the setting to those used by the prior release. All default settings can be reverted to the prior release by using the command, “Defaults == Pre 2006-06-AA”.

Table 18.14: Default Changes in the 2006-06 Release and Backward Compatibility to 2005-05

Command Change	Description of Change
Uses a new set of defaults for a number of commands.	The new defaults will produce different results. For established models run using the 2005-05-XX builds, use Defaults == PRE 2006-06-AA to use the previous default settings. Each of the new default settings and their affects are discussed in the rows below.
Cell Wet/Dry Depth == 0.002 (previously 0.05) and Cell Side Wet/Dry Depth == 0.001 (previously 0.03)	The most pronounced effect of the shallower wet/dry depths is likely to occur in areas that are still filling at the flood peak, such as behind a levee that is only just overtopped. The shallower wet/dry depths provides a greater flow depth for a longer period over the levee.
Adjust Head at ESTRY Interface == OFF (previously ON)	Usually does not have a major influence on results except where very high velocities occur.
Boundary Cell Selection == Method C (previously Method A) and Line Cell Selection == Method C (previously Method A)	May select slightly different cells along boundary/link lines. This may cause a difference where the line is along the top of levee, possibly creating a “hole” in embankment.
Viscosity Formulation == Smagorinsky (previously Constant) and Viscosity Coefficient == 0.2 (previously 1.0)	Can have a significant effect where the viscosity term is influential. This occurs where the friction term is less dominant (i.e. low Manning’s n and/or deeper water such as the lower, tidal, reaches of rivers).
Structure Losses == ADJUST (previously FIX)	Can have a significant affect in the vicinity of structures within a 1D network and for culvert networks. Does not affect 1D structures linked to a 2D domain or at the structure ends not connected to another 1D channel.
Storage Above Structure Obvert (%) == 5 (previously CHANNEL WIDTH)	Usually negligible effect unless the model storage is predominantly within 1D closed sections (i.e. B, C and R channels). The 1D domain is likely to be more sensitive to instabilities due to the much smaller storage above the top of the closed sections, and a smaller 1D timestep may be required and/or the Storage Above Structure Obvert (%) increased.
Depth Limit Factor == 10 (previously 1)	No effect as previously the model would have become “unstable” as the trigger for an instability was the top of the channel/node.
Culvert Flow == Method C (previously Method B)	Usually only minor effects plus improved stability.
Culvert Add Dynamic Head == ON (previously OFF)	Minor influence.
Bridge Flow == Method B (previously Method A)	Negligible influence plus improved stability. However, note the different treatment of energy losses once the bridge deck obvert/soffit is submerged if a BG or LC table is specified.
WLL Approach == Method B (previously Method A)	Only affects the presentation of results. Note, that Method A is no longer recommended or supported.
Apply All Inverts == ON (previously OFF)	Does not affect hydraulic calculations, however, if a Blank, B or W channel is now lowered/raised because the inverts are now used, this will affect results/stability - see note at end of Apply All Inverts).