FLUENT 6 - Write pressure gradient history in a file (obtained from a translational periodic case)

It is possible to monitor pressure gradient (pressure drop/unit length) as a function of iteration.
This can be done in the following panel:
Solve-> Monitor -> Statistics

However writing this information to a file is not possible.
If you want to write the pressure gradient to a file at each iteration, you can use a scheme or a UDF:

1- Scheme example: monitor-periodic.scm

;;; This Scheme function is computing
;;; pressure gradient of a translational periodic
;;; Usage

;;; 1) Read the case and data file,
;;; 2) File>Read>Scheme .. this file (monitor-periodic.scm)
;;; In order to load this file automatically
;;; Create a .fluent file in your home directory in which you type the following line:
;;; (load "~/mypath/monitor-periodic.scm")

;;; 3) Set a monitor command in GUI
;;; Solve->Execute Commands
;;; with the following content
;;; (write-my-deltap filename)
;;; filename: a string containing the name of your output file
;;; Example:
;;; (write-my-deltap "monitor1.out" )

;;; 4) Set the frequency of executions - Every "n" Time steps or iterations

;;; 5) Run
;;; Do not change below this line
;;; ==========================================================
(define (write-my-deltap filename)

(let ((uport)(niter (%iterate 0)))

(if (file-exists? filename)

(set! uport (open-file filename "a+"))
(let* ((fn filename))
(set! uport (open-file fn "w+"))
(format uport "Pressure gradient as a function of iteration")
(newline uport)
(format uport " ~a" niter)
(format uport " t ~a" (rpgetvar 'periodic/pressure-derivative))
(newline uport)
(flush-output-port uport)
(close-output-port uport)
;;; End of scheme file

2- If you want to retrieve the pressure gradient in a UDF. You can use a command like this:

real deltap=RP_Get_Real('periodic/pressure-derivative);

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