Issue with dynamic BC and sparse.unf generation in AEM3D preprocessing

Question

Hi,

I am currently setting up a simulation for a lagoon using AEM3D with dynamic boundary conditions. I’m using a dynamic.xml file for boundary condition inputs and have provided a custom bathymetry file named LagoonBathymetry.dat given in the example

I am getting following error:

AEM3D preprocessor will overwrite old output files  

To disable this option insert no overwrite in file run_pre.dat

preprocessor output file:  bathymetry/LagoonBathymetryOut.txt  

debugging output file:     debug_pre.txt  

echo output file:          echo_pre.txt

**** WARNING *****  

no boundary condition sets found  

This is not a problem if no sets are needed.

FATAL ERROR  

Open bathymetry value at cell (i,j)            1           4  

with no OPEN BC specified at cell in bc.dat

What are the required steps to make the dynamic BC input structure work properly? The documentation regarding how to structure bathymetry.dat, dynamic.xml, and related files when using dynamic BCs? Could you please clarify how open boundary cells (e.g., for inflows/outflows) must be defined in the bathymetry file and linked in the BC setup? In my case, the boundary condition at (1,4) is already an open boundary only : 999.00 999.00 999.0 888.00 999.00 999.00 999.00 999.00 999.00. How to generate a sparse and a usedata input files properly for AEM3D with Dynamic BC?

Thanks for the help in advance.

Answer 1

Hi,

You're confusing a couple of things here.  

Open boundaries are cells where the boundary condition will be specified with a tidal height rather than a flow.  The flow is then calculated as part of the free surface solution, taking into account the difference between the specified height at the boundary and the modelled height inside the domain.

Dynamic boundary conditions are a way of calculating any temporal boundary condition (such as inflow rate, inflow temperature, air temperature, etc) based on some modelled variable, rather than having to specify it as a timeseries before the simulation is started.  So, for example, we could determine the outflow rate through an offtake based on the simulated water level to mimic how a reservoir is operated.

The error you are getting in your pre-processing is that you have specified an open_cell (888) in your bathymetry file, but do not have this cell listed as an open_cell in the bc.dat file.

In the Lagoon example in the download, the LagoonBC.dat file has.

1  open_cell   Ocean

1       4       :

Chris