[Ash Kot]

Hello FLUENT Users,

Recently ANSYS has added 'pdf_stability_marker' option in GUI with respect to one which was available since earlier times.
After going through documentation this is what mentioned about this 'pdf_stability_marker':
In FLUENT User guide

19.1.13. Enabling Robust Numerics for Combustion with a PDF Table
You may be able to increase the robustness of combustion simulations that use a PDF table by applying poor mesh numerics during the calculation. When you initialize or read data for a case with non-premixed or partially premixed combustion, a cell register named pdf_stability_marker is created (which marks cells where the enthalpy—as defined by the PDF Table Heat Loss/Gain field variable described in Alphabetical Listing of Field Variables and Their Definitions—is below the minimum PDF table value), and this cell register is used as part of the settings for a register-based definition named pmn_pdf_stability_marker that applies poor mesh numerics treatment every 5 iterations (for steady cases) or every 2 time steps (for unsteady cases). Note that this definition is automatically created, but is deactivated by default; in order to use it in the current session of Fluent, you must enter the following text command prior to running the calculation:

> solve/set/poor-mesh-numerics/register-based/edit pmn_pdf_stability_marker active? yes

If you would like to use such definitions in all future sessions of Fluent without having to enter the previous text command, you can enable the Robust Numerics for Combustion with PDF Tables option in the Simulation branch of the Preferences dialog box (accessed through File/Preferences...).

Note that if the default settings for this treatment are not appropriate for your case, you can edit the cell register and/or register-based definition for poor mesh numerics, as described in Manage Cell Registers and Robustness with Meshes of Poor Quality, respectively.

I still didn't understand correctly can anyone explain me how to use it correctly by default value for 'cells having less than' option is -1, what should I mentioned instead of -1 or is it correctly defined?