[kastarkas]

Hello everyone.
What are the possibilities in cfx to input a range of pressure (as a preload) as inlet boundary condition ?
(Note : Outlet BC would be mass flow rate)
Or is it ok to provide the values and try those, one at a time, per run.
Thanks in advance .

[Gert-Jan]

There are mupltiple options:

- You can create different configurations in Pre. This will allow you to set different inlet pressures. Then you will end up with multiple result files.

- It is also possible to create a single file in which you define a CEL-expression that sets the pressure at the inlet. This can increase by e.g. 1000 Pa every 200 iterations. Then by setting a backup frequency of 200, CFX will write a backup every time you change the pressure. Make sure that CFX keeps your backup files (expert parameter).
Don't know how the expression looks like, but it is possible.
This is a risky one since it is error prone, but the fastest.

- Outside Workbench (use the command line from the CFX-launcher) run a batch file that runs your definition file with different settings. THe batch file can contain (as an example):
cfx5solve -def file.def -ccl P1000.ccl
cfx5solve -def file.def -ccl P2000.ccl
cfx5solve -def file.def -ccl P3000.ccl
.
.
.

Where P1000.ccl is a text file. The text contains the settings of the new run that you can copy from a previous output file. Then by changing the inlet pressure to 1000 Pa, cfx5solve will run your file.def with 1000Pa. In fact, the original settings in the def-file are overruled by the settings in the ccl-file.

[kastarkas]

Oh thanks a lot Gert...can I go like ......increasing the pressure after it has reached convergence (instead of specifying the iterations) and then running the same with the next pressure value and so on..?

[Gert-Jan]

First question: Are you running CFX through Workbench? Or stand alone?

[kastarkas]

Its CFX via workbench..

[Gert-Jan]

Then there is no fancy workaround. Two options remain:
1. Use my first option: create multiple configurations in Pre. And let Workbench run them all. Don't ask me how. I never use Configurations nor Workbench.
2. Manually. Define a run with 100000 iterations and convergence criterium 1e-10 max. Let it run in Workbench. Then, in the solver manager, when you think convergence is ok, a) select the icon "Dynamically edit the settings of the run in Progress", b) Press yes to save a back up file, c) in the tree, look for the inlet pressure and change it to a new value d) save and exit.
The solver manager will continue with the new inlet pressure. The backup file is the final result with the previous inlet pressure. Look for it on your HD-Drive, make a copy of it (or move it) and rename it to something logical for you. You can change the file-extension from .bak to .res, to make it a results file instead of back-up file. Contents is exactly the same.
During the run, you can repeat steps a-d as many times as you like, until you have 100.000 iterations or you press stop. Just make sure you make a copy of the .bak-files.

Regs, Gert-Jan