Launch CFX#

This page explains how to launch Ansys CFX sessions using PyCFX.

The initial release of PyCFX with Ansys CFX 2025 R2 Service Pack 3 supports running CFX sessions only on the local machine (the same machine where the Python session runs).

Launch from local installation#

Use the from_install() method to launch CFX with a locally installed version of Ansys CFX.

Use this method when CFX is installed on your local machine and you want to run CFX only on the local machine.

Example calls:

import ansys.cfx.core as pycfx

pypre = pycfx.PreProcessing.from_install()

pysolve = pycfx.Solver.from_install(solver_input_file_name=solver_input_file_name)

Useful arguments for the from_install() method follow:

  • product_version: CFX version to launch. If not specified, the method launches the latest supported version.

  • case_file_name: Path to a case file (.cfx) on the local file system to initialize a PreProcessing session.

  • solver_input_file_name: Path to a CFX-Solver input file (.def or .mdef) on the local file system to initialize a Solver session.

  • run_directory: Run directory (.dir) for an existing CFX-Solver run to initialize a Solver session.

  • results_file_name: Path to a results file (.res or .mres) on the local file system to initialize a Solver or PostProcessing session.

  • additional_arguments:List of additional command-line arguments to pass to the cfx5pre, cfx5solve, or cfdpost commands when launching the session or starting the CFX-Solver.

Launch from an existing session#

You can launch Solver and PostProcessing sessions from existing PyCFX sessions.

  • Launch a Solver session from an existing PreProcessing session. At the point of launch, the Solver session captures and stores the existing model setup in CFX-Pre, ready to start the run. You can continue editing the setup in the PreProcessing session without affecting the previously launched Solver session.

  • Launch a PostProcessing session from an existing Solver session. If the CFX-Solver run is complete, the results file opens. If the CFX-Solver run is not complete, the new PostProcessing session waits for it to finish before reading the results.

When you start a PyCFX session from another PyCFX session, the new session inherits settings from the existing session. For example, if you start a PreProcessing session with the product_version argument, a new Solver session initialized from the PreProcessing session also uses that argument.

Example calls:

pysolve = pycfx.Solver.from_session(pypre)

pypost = pycfx.PostProcessing.from_session(pysolve)

Enable logging#

PyCFX supports running with logging enabled. Use this code to enable logging:

>>> import ansys.cfx.core as pycfx
>>> pycfx.logging.enable()
PyCFX logging file ...
Setting PyCFX global logging level to DEBUG.

For more information, see Configure logging.