February 1, 2021 at 2:21 pmMoussaSubscriber
I am currently modeling transient natural convection of a liquid inside a tank but my simulation doesn't converge using SIMPLEC algorithm as mentioned in the article.February 1, 2021 at 2:48 pmRobAnsys EmployeeDo you have a gas phase present too? Mesh (and cell) quality and time step are more likely to be causing the problems. nFebruary 1, 2021 at 3:00 pmFebruary 1, 2021 at 3:53 pmFebruary 1, 2021 at 4:02 pmDraxlerSubscriberDid you change the Residual values to a smaller number than the default? nMost youtube videos change them to 10-6 and I was doing that as well. For very simple geometries, this works, but for complex ones, I was also having a problem with converging. I changed them back to 10-3 and the solution did converge. nSmaller residuals lead to more accurate results as far as I know. But in my comparison of the 2, there was very little difference.nnFebruary 1, 2021 at 4:11 pmRobAnsys EmployeeGiven the SIMPLEC has only done 140 iterations you may want to try running it on. Also note, the PBCS solver uses a courant number or time factor so may converge better if you've not adjusted any of the under relaxation defaults. nFebruary 1, 2021 at 4:25 pmMoussaSubscriberThank younThe energy residual is falling under e-11, for the sufficient convergence of the iterative solutions, they use e-10 for the energy equation and e-0u00035 for the other conservation equations.nThe results at the initial state (t = 0) are obtained from the steady-state calculation at ptank = 1atm ( temperature contours posted earlier), there is a big difference between the two algorithms.nResiduals using SIMPLEC algorithm in steady-state simulation.nnFebruary 1, 2021 at 4:28 pmRobAnsys EmployeeWhich isn't converged. Try dropping the momentum under relaxation factor. What density model are you using?nFebruary 1, 2021 at 4:52 pmFebruary 2, 2021 at 3:15 pmMoussaSubscriberAny advice? Thank you in advance.nFebruary 2, 2021 at 4:01 pmRobAnsys EmployeeI'd be more worried about the continuity equation in the first case. Given PBCS uses a time factor I suspect that's why the convergence is better. Converge the first case properly and then compare the results. nViewing 10 reply threads
Ansys Innovation Space
- You must be logged in to reply to this topic.
Boost Ansys Fluent Simulations with AWS
Computational Fluid Dynamics (CFD) helps engineers design products in which the flow of fluid components is a significant challenge. These different use cases often require large complex models to solve on a traditional workstation. Click here to join this event to learn how to leverage Ansys Fluids on the cloud, thanks to Ansys Gateway powered by AWS.
Earth Rescue – An Ansys Online Series
The climate crisis is here. But so is the human ingenuity to fight it. Earth Rescue reveals what visionary companies are doing today to engineer radical new ideas in the fight against climate change. Click here to watch the first episode.
Subscribe to the Ansys Blog to get great new content about the power of simulation delivered right to your email on a weekly basis. With content from Ansys experts, partners and customers you will learn about product development advances, thought leadership and trends and tips to better use Ansys tools. Sign up here.Trending discussions
- Suppress Fluent to open with GUI while performing in journal file
- Floating point exception in Fluent
- What are the differences between CFX and Fluent?
- Heat transfer coefficient
- Getting graph and tabular data from result in workbench mechanical
- Difference between K-epsilon and K-omega Turbulence Model
- The solver failed with a non-zero exit code of : 2
- Time Step Size and Courant Number
- Mesh Interfaces in ANSYS FLUENT
- error: Received signal SIGSEGV
Top Rated Tags
© 2023 Copyright ANSYS, Inc. All rights reserved.Ansys does not support the usage of unauthorized Ansys software. Please visit www.ansys.com to obtain an official distribution.