Slowing increase pressure inlet to get steady-state convergence?

flow-mo-mcfadden · March 29, 2019, 15:13

Hi folks, I'm assessing the steady state condition of a primary and entrained flow in a pipe using Ansys Workbench with Fluent (v19.2). If I initialize (default hybrid initialization) with my primary flow at my desired pressure (2,000psi), the solution diverges. However, if I initialize at a 1,000psi BC, execute, let the solution converge then double the pressure inlet to my desired value and continue the calculation, then I get good convergence. I've tried a number of things (I'm very untrained with CFD mind you) including solution steering and have not been able to get convergence right off the bat.

In exploring the manual, I found that under "Calculation Activities" there seems to be a way of adjusting the inputs midway through the execution. Anybody have a hint on how I could change my pressure inlet value BC. I want to avoid the "man-in-the-loop" as I'm hoping to do a design optimization study involving a couple hundred iterations. Again, its steady state so the fact that I'm having this issue may be caused by something else.

LuckyTran · March 29, 2019, 17:05

You have to learn the text commands (the TUI commands). Press enter to see all available TUI commands.

A faster way might be to google/search for a Fluent journal file to get some ideas on what these commands might look like.

It will look something like:
/define/boundary-conditions/ blah blah blah

Yet another way could be to just record a macro.

March 29, 2019, 15:13	Slowing increase pressure inlet to get steady-state convergence?	#1
flow-mo-mcfadden New Member OH Join Date: Dec 2018 Posts: 11 Rep Power: 7	Hi folks, I'm assessing the steady state condition of a primary and entrained flow in a pipe using Ansys Workbench with Fluent (v19.2). If I initialize (default hybrid initialization) with my primary flow at my desired pressure (2,000psi), the solution diverges. However, if I initialize at a 1,000psi BC, execute, let the solution converge then double the pressure inlet to my desired value and continue the calculation, then I get good convergence. I've tried a number of things (I'm very untrained with CFD mind you) including solution steering and have not been able to get convergence right off the bat. In exploring the manual, I found that under "Calculation Activities" there seems to be a way of adjusting the inputs midway through the execution. Anybody have a hint on how I could change my pressure inlet value BC. I want to avoid the "man-in-the-loop" as I'm hoping to do a design optimization study involving a couple hundred iterations. Again, its steady state so the fact that I'm having this issue may be caused by something else.

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March 29, 2019, 17:05		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,750 Rep Power: 66	You have to learn the text commands (the TUI commands). Press enter to see all available TUI commands. A faster way might be to google/search for a Fluent journal file to get some ideas on what these commands might look like. It will look something like: /define/boundary-conditions/ blah blah blah Yet another way could be to just record a macro.