Watlab for dummies#

Watlab works as a Python API, which means that you need to know how to run a Python script, use a Python interpreter and load a Python library. See also the links proposed in the previous chapter for some useful tutorials.

To run your watlab simulation, you will need three things:

A mesh constructed with GMSH (see our tutorial or download it);
A proper model;
Some initial and boundary conditions.

This page will guide you through the two last (but most important!) steps with Watlab.

Set up the Watlab model#

Starting using watlab and initializing the model is very easy. You would need to do three steps :

Load the adapted model module from watlab (here, it is hydroflow)
Load the mesh
Build the model based on that mesh.

Here we provide a first example based on the hydrodynamic module of Watlab : Hydroflow.

# Load the module
from watlab import hydroflow

# Load the mesh
mesh = hydroflow.Mesh('path/to/tutorial-mesh.msh')

# Impose a meshchecking for this simulation (only if needed, default = False)
mesh.meshchecking = True

# Create the model
model = hydroflow.HydroflowModel(mesh)

That’s it, your model is set up !

Parameterize the model#

The model comes with numerous functions and parameters that allow to set up your simulation: initial conditions, boundary conditions, running parameters, etc.

The syntax to modify a parameter is always model.parameter = value;
The syntax to add an initial condition is model.set_condition(regions, values) where regions is a (list of) name of region from the mesh, and values is a (list of) values corresponding to the condition;
The syntax do add boundary conditoons is model.set_condition(regions, values) where bounadry is a (list of) name of boundary from the mesh, and values is a (list of) values corresponding to the condition;

In the following example, the name of the simulation is modified, and the initial water level is fixed in the “Filled area” of the mesh.

model.name = "my simulation name"
model.set_initial_water_level("Filled area", 0.15)
model.set_wall_boundaries(["Boundaries down", "Boundaries up", "Boundaries right", "Boundaries left"])

The list of parameters and conditions is given in the documentation with an exhaustive explanation of the entry parameters.

To get the conditions, just call model.get_initial_conditions() or model.get_boundary_conditons().

Launch the simulation#

Finally, to run the code, you will need to export the data files, then solve the model :

model.export_data()
model.solve()

This last line runs the simulator file. If this latter does not exist, the C++ (calculation code) will be compiled and run. If it exists, the simulation will start directly.

Post-process the results#

Section in construction.