Rocky 2026 R1 Student – Fluent Journal File Error During Rocky-Fluent Coupling

[kamilayu]

Hello,

I am using ANSYS Rocky 2026 R1 Student coupled with Fluent 2026 R1 Student for a CFD-DEM simulation.

Model Information

• Rocky 2026 R1 Student

• Fluent 2026 R1 Student

• CFD mesh: approximately 62,500 cells

• Geometry size: 200 × 200 × 100 µm

• Approximately 75 particles generated successfully in Rocky

• Two-way Fluent coupling enabled

Problem Description

The coupled simulation does not proceed correctly after initialization.

Rocky generates the particle bed successfully and Fluent launches. The coupling process begins, but Fluent reports the following messages:

Warning: An error or interrupt occurred while reading the journal file.
Some commands may not have been completed.

and

Error: CAR: invalid argument [1]: wrong type [not a pair]
Error Object: #f

Rocky Messages

Rocky also reports:

averaging warning: target volume fraction of 0.48 not reached after 1000 iterations limit

However, particles are successfully created and visible in the domain, so I am not sure whether this warning is related to the main failure.

Observations

• Rocky starts normally.

• Particle generation completes.

• CFD mesh is exported.

• Fluent and Rocky establish communication.

• Fluent then reports the journal-file error shown above.

• The simulation does not advance as expected after this point.

Questions

1. Does the Fluent error

Error: CAR: invalid argument [1]: wrong type [not a pair]

indicate a corrupted journal file or coupling script?

2. Could Rocky-Fluent coupling generate an invalid Fluent command during initialization?

3. Is this a known issue in Rocky 2026 R1 Student / Fluent 2026 R1 Student?

4. Which log files should I inspect to identify the command that caused the journal-file failure?

5. The setup is being operated from workbench

Any guidance would be greatly appreciated.

Thank you.

[Lucas Hoenicke]

Hello,

To successfully performe a coupled rocky-fluent simulation, you must pay attention to the limitations , please check.
Also, read the tutorials: Chapter 14: Tutorial – Fluidized Bed
Chapter 16: Tutorial – Mixing Tank
They will help you understand how it works practically.

Please, see if this helps or not. If it doesn't, then please report back here (in the same thread).