User Forum of Software BASEMENT

dehrbar

User

Registered: 2021-01-05

Posts: 1

Missing tag "flood_tracking" / use of "tracking_timestep"

Dear colleagues,

According to the manual, there should be a simulation output "flood_tracking" (table 3.9). Unfortu-nately, we cannot find it in the OUTPUT block of the simulation menu. However, there is a FLOOD block in the setup menu where a "tracking_timestep" can be defined. We suppose that this is what we are looking for, but why do we have to define a timestep? We expect that every computational time step should be included in the tracking of max / min values by default...

Thanks in advance for some additional explanations!

NumericalSam

User

From: Switzerland

Registered: 2022-04-01

Posts: 14

Re: Missing tag "flood_tracking" / use of "tracking_timestep"

This is what you are looking for.
I can't tell you the exact reason why a timestep has to be defined, but I guess it comes for computational / time savings reasons. If you want to get the absolute max out of this, I'd suggest a tracking time step of some seconds. However, in most situations the maximum values will be achieved for some minutes and therefore a larger tracking time step will be enough. Depending on the situation of course.
I'd be interested in hearing the explanation from the developers though!

Matthias Bürgler

Developer

From: Zürich

Registered: 2019-04-04

Posts: 175

Re: Missing tag "flood_tracking" / use of "tracking_timestep"

The flood tracking feature results in additional computation cost. Increasing the tracking_timestep provides the option to reduce this cost costs. If you want the tracking to occur at every computational time step you can just set a tracking_timestep that is clearly smaller than the expected computational time step.

Note that defining a tracking_timestep smaller than the computational time step will not affect the computational time step. The latter is purely defined by hydraulics, cell size and the user-specified CFL number.