May 11, 2022 at 8:35 pmbsmith643Subscriber
Hi, I'm relatively new to Fluent and I'm running a pretty simple flow analysis on a model. I'm looking at velocity and pressure drop for air flow through a heat exchanger. I haven't had any trouble meshing the model or setting up the analysis in Fluent, but when I start the calculation it never gets to the first iteration. I can see the background task running on my task manager but it never progresses. I have left it overnight before to see if it could make progress, but it was still on 0% and no iterations when I came in the next morning. The mesh has decent quality (0.2) and there are no errors when I run mesh checks or when I do the case check prior to beginning the calculation. I'm using hybrid initialization.
Any ideas where to start looking?May 12, 2022 at 8:20 amNikhil NaraleAnsys EmployeeHello,
I would suggest you to try out following things:
1: Can you click on 'Check Case' button in the Run Calculation tab? Check what it has to say.
2: Can you try initializing using standard method and assign non-zero value to the flow variables?
Can you also tell,
1: What are the boundary conditions?
2: Are the material properties constant or defined as a function?
May 12, 2022 at 8:57 amRobForum ModeratorCan you post the panel you hit iterate on too.
May 12, 2022 at 1:27 pmbsmith643SubscriberCheck case doesn't have any recommendations.
I haven't tried that.
Boundaries are 1 mass flow inlet with a fixed gas flow rate and a pressure outlet set to 0.
Using the standard Fluent "air" material.
May 12, 2022 at 1:37 pmbsmith643SubscriberCheck case has no recommendations
This didn't work either
1 mass flow inlet with constant flow, 1 pressure outlet at gauge pressure
Using Ansys default air for fluid material. No solid geometry in the model.
May 12, 2022 at 1:38 pmbsmith643SubscriberSnip of the iterate screen.
May 12, 2022 at 1:41 pmRobForum ModeratorPlease post images in-line as staff aren't permitted to open attachments.
May 12, 2022 at 1:44 pmMay 12, 2022 at 2:01 pmRobForum ModeratorOK, that rules out the reporting interval clanger - ie you'd set the iterations in the update input and then nothing displays anywhere. With constant density you should use a velocity boundary for stability (won't alter the current issue). Does Mesh Check flag anything? How many cells have you got, and how much RAM?
May 12, 2022 at 2:43 pmbsmith643SubscriberNothing from mesh check. Cell count is 35,933,399. RAM is 128GB
May 12, 2022 at 3:18 pmRobForum ModeratorThat should be OK but with only 8 cores it'll take a while to do the first iteration. How many monitors are there? Do you have 8 physical cores on the machine, if you're relying on hyperthreading it'll not end well.
May 12, 2022 at 3:28 pmbsmith643SubscriberI've left for about 14 hours before and it never completed the first iteration. Do you think it might take longer than that?
Computer has 12 cores on it.
May 12, 2022 at 3:40 pmRobForum ModeratorNo, I'd expect 10s of minutes. Even if the model then failed it should have reported something. I'd expect you be using around 90GB RAM too.
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