May 8, 2023 at 1:16 pmFabio FerrarioSubscriber
I am doing diffusion evaporation simulations that use an UDF to govern the rate of evaporation (or vapour inlet, since I'm not simulationg the liquid phase). I have noticed that if I try to do this simulation without selecting the Inlet Diffusion option in the species model tab, I don't have molar fraction continuity next to the surface. This means that concentrations above the evaporating pool are different from what you would expect, heavily diluted compared to the saturation condition (e.g., it dilutes to less that 60% the expected value). Selecting Inlet Diffusion fixed the problem, but I am left wondering on why it does. I could not really find much info in literature on how Inlet Diffusion works, but I suppose it uses the molar fraction defined on the cells of the inlet and compares it to the molar fraction of the cells adjacent to it. From this, it uses the usual Fickian formulas to define a mass inflow.
My doubt is the following : If i have both UDF that does the same exact thing as the Inlet Diffusion, when both are activated, do the effects add up?
When comparing to experimental data, I have a sensible over prediction in the transient part of the process, but once it reaches a stationary condition, mass flow rates seem to align with experimental data (for the most part).
May 9, 2023 at 10:57 amRobAnsys Employee
Inlet diffusion will diffuse material from the boundary into the domain: I can't comment much further as the manual isn't overly clear. Given you're adding mass at (probably) a very slow rate you'll see diffusion/convection take material away from the boundary depending on near surface mesh resolution and flowfield.
- 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.
- 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
© 2023 Copyright ANSYS, Inc. All rights reserved.