= Modelling Questions =
== What type of problems is ANUGA good for? ==

General 2D waterflows in complex geometries such as
dam breaks, flows among structures, coastal inundation etc.

== What type of problems are beyond the scope of ANUGA? ==

See the chapter on "Restrictions and Limitations" in the [http://datamining.anu.edu.au/~ole/anuga/user_manual/anuga_user_manual.pdf User Manual].

== Can I start the simulation at an arbitrary time? ==

Yes, using {{{domain.set_time()}}} you can specify an arbitrary
starting time. This is for example useful in conjunction with a
file_boundary, which may start hours before anything hits the model
boundary. By assigning a later time for the model to start,
computational resources aren't wasted.

== Can I change values for any quantity during the simulation? ==

Yes, by using {{{domain.set_quantity()}}} inside the domain.evolve
loop you can change values of any quantity. This is for example
useful if you wish to let the system settle for a while before
assigning an initial condition. Another example would be changing
the values for elevation to model e.g. erosion.

== Can I change boundary conditions during the simulation? ==

Yes, see the example in the section "Changing boundary conditions on the fly" in the 
[http://datamining.anu.edu.au/~ole/anuga/user_manual/anuga_user_manual.pdf User Manual].

== How do I access model time during the simulation? ==

The variable {{{t}}} in the evolve for loop is the model time.
For example to change the boundary at a particular time (instead of basing this on the state
of the system as in the "Changing boundary conditions on the fly" section of the manual)
one would write something like
{{{
for t in domain.evolve(yieldstep = 0.2, duration = 40.0):
    if Numeric.allclose(t, 15):
        print 'Changing boundary to outflow'
        domain.set_boundary({'right': Bo})
}}}
The model time can also be accessed through the public interface {{{domain.get_time()}}},
or changed (at your own peril) through {{{domain.set_time()}}}.

== Why does a file_function return a list of numbers when evaluated? ==

Currently, file_function works by returning values for the conserved
quantities {{{stage}}}, {{{xmomentum}}} and {{{ymomentum}}} at a given point in time
and space as a triplet. To access, or example, {{{stage}}} one must specify element 0 of the
triplet returned by file_function, to access {{{xmomentum}}} one must specify element 1 of the triplet, etc.

== How do I use a DEM in my simulation? ==

You use {{{dem2pts}}} to convert your DEM to the required .pts format. This .pts file is then called
when setting the elevation data to the mesh in {{{domain.set_quantity}}}.

== What sort of DEM resolution should I use? ==

Try and work with the '''best''' you have available. Onshore DEMs
are typically available in 25m, 100m and 250m grids. Note, offshore
data is often sparse, or non-existent.

Note that onshore DEMS can be much finer as the underlying datasets from which they
are created often contain several datapoints per squate metre.
It may be necessary to thin out the data so that it can be imported
without exceeding available memory. One tool available on the net is called 'decimate'. (Need reference?).