September 1, 2022 at 3:30 amZ.PAN-2Subscriber
Hi, Fluent Specialists!
I am using Raoult’s law to model the vaporization of liquid water below the boiling temperature by using (1) multiphase (mixture) species transport, (2) energy model, and (3) k-e model with enhanced wall function (thermal effects).
I have some problems with the model: (1) the model won’t converge by using either the steady solver or the transient solver (even when the time step size reduces to 1e-7), and (2) the temperature of the vapor mixture reaches 400+ Kelvin or even 1000+ Kelvin, while the temperature of the liquid drops to something like 1 Kelvin. Initially, the whole system is 353 Kelvin.
The system is a 2-D triangle, with an outlet on top and no inlet. There are two phases: liquid water (primary phase) and mixture (air + water vapor). The saturation pressure is defined by piecewise linear method. The backflow is 300 Kelvin pure air. The gravity is activated. I am using PISO, Presto! schemes and second-order upwind for spatial discretization.
What settings should I change? I appreciate any feedback!
September 1, 2022 at 8:55 amDanicaAnsys Employee
Is this a close up on part of the model, where is the triangle? Also, where is the heat coming from and has it got the right units? Have you changed any of the values for enthalpy?
Could also be beneficial to check mesh refinement.
September 1, 2022 at 11:30 amZ.PAN-2Subscriber
Hi, Danica. Thank you for the feedback.
(1) It's a typo. There is no triangle, it's a 2d rectangle.
(2) There's no heat addition in the system. We expect the vaporization process and backflow will cool down the system. (At the beginning, the bottom half of the rectangle contains the liquid and the upper half of the rectangle contains the mixture (0.02 mass fraction of vapor))
(3) I didn't change any enthalpy. Should I change it?
(4) I think the mesh is fine. Minimum Orthogonal Quality = 1.0 Maximum Aspect Ratio = 1.00245e+01.
By the way, I found out that the residuals of continuity and energy always diverge first. Is there any way to fix it?
- You must be logged in to reply to this topic.
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.
- 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
- The solver failed with a non-zero exit code of : 2
- Difference between K-epsilon and K-omega Turbulence Model
- Time Step Size and Courant Number
- Mesh Interfaces in ANSYS FLUENT
- error in cfd post
© 2023 Copyright ANSYS, Inc. All rights reserved.