Slowing increase pressure inlet to get steady-state convergence?

flow-mo-mcfadden · March 29, 2019, 14:13

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, 16:05

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, 14:13	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.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Pressure Inlet VS velocity Inlet difference	Mohsin	FLUENT	9	January 4, 2021 10:34
Ansys CFX problem: unexpected very high temperatures in premix laminar combustion	faizan_habib7	CFX	4	February 1, 2016 17:00
Pressure Inlet: question about total pressure	I-mech	FLUENT	0	July 13, 2014 05:38
Pressure Inlet Boundary Condition Issue	zoeburton1987	FLUENT	0	May 15, 2012 09:20
error message	cuteapathy	CFX	14	March 20, 2012 06:45

March 29, 2019, 16:05		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,676 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.