Note

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Run a simulation - Step by step#

With interactive execution, OpenGeoSys provides a Python interface that lets you advance a simulation one step at a time, inspect intermediate results, and react before continuing. This mechanism underlies what we mean by Co-simulation: the simulation can exchange information with external analyses or tools during runtime—for example, by dynamically adjusting boundary conditions. In this guide, we will show how to:

Imports and definitions#

from ogs import OGSMesh

from ogstools.examples import load_model_liquid_flow_simple

Select a Project#

We will start with a simple liquid flow example and set the OGS execution to interactive.

model = load_model_liquid_flow_simple()
model.execution.interactive = True

Initialize the simulation and first step#

Use the same arguments as when calling OGS from command line, a list of possible argument are documented under https://www.opengeosys.org/docs/userguide/basics/cli-arguments/

By constructing a SimulationController object we start OpenGeoSys and it (only!) runs time step 0.

simc_1 = model.controller()

print(f"The current simulation time is: {simc_1.current_time} s.")
print(f"The end time defined is: {simc_1.end_time} s.")

The current simulation time is: 0.0 s.
The end time defined is: 100.0 s.

Advance the simulation by a one step#

status = simc_1.execute_time_step()
print(f"The current simulation time is: {simc_1.current_time} s.")

The current simulation time is: 10.0 s.

Basic simulation loop#

The simulation runs step-by-step until a user specified condition is met. This further allows you to manipulate data arrays associated with the mesh or adapt the logic inside the loop.

while (
    # Here, the condition is when simulation reaches the end time:
    simc_1.current_time
    < simc_1.end_time
):

    # Add here your specific code with mesh manipulation:
    my_mesh: OGSMesh = simc_1.mesh("domain")
    simc_1.execute_time_step()

sim = simc_1.run()
print(sim)

Simulation id: 20260323_113731_429225
   (not saved (planned: file:///tmp/ogstools_root/Simulation/20260323_113731_429225))
  Model: saved to file:///tmp/ogstools_root/Model/20260323_113731_016493
  Result: saved to file:///tmp/ogstools_root/Result/20260323_113731_117391
  Log file: file:///tmp/ogstools_root/Result/20260323_113731_117391/log.txt
  MeshSeries: file:///tmp/ogstools_root/Result/20260323_113731_117391/LiquidFlow_Simple.pvd
  Status: completed successfully (results available)

Advance examples with mesh manipulation#

Manipulate the mesh with either

Total running time of the script: (0 minutes 0.466 seconds)