For Fluent 18.1 and 18.2 there is a pre-defined report definition called “per-pr-grad”. This is renamed to “periodic-pressure-gradient” in Fluent 19.0. You can use this definition to crate your monitors and write the result into a file. For Fluent 18.0 and before or for UDF access refer to solution 1119. Note that there is a defect in the parallel versions of Fluent 18.1 and 18.2. The pressure gradient is always reported as zero. This is just a display defect that doesn’t exist for the serial versions. Run at least one iteration in serial to update the value. Note that for Fluent 18.2 the behavior for the serial version changed. Start Fluent parallel with zero compute nodes (startup option -t0) to access the legacy serial version. This does not apply to Fluent 18.1.