March 28, 2022 at 5:47 pmAnadi_MondalSubscriber
Would anyone tell me the conditions of using EWF ? Why EWF may fail? Actually, I am getting negative film velocity for the upward vertical tube(air/water annular flow in a tube). I notice that when maximum film thickness and film velocities are 0.67mm and 1.3 m/s respectively , everything is running smoothly. But, when the maximum film thickness in the simulation is 1.05mm , film velocity is negative. Although, film Re is less than 400 for both cases. So, what may be the reason for negative film velocity or film Re?
I will be highly pleased if you respond with a reference showing critical film thickness/film velocity/film Re number for the EWF model. Actually, I am struggling with this problem for a longer period but didn't able to solve the problem. From my simulation experience I notice that when the film thickness is more than 1 mm, it is showing negative film velocity.
AnadiMarch 29, 2022 at 10:43 amRobAnsys EmployeeIt depends on the flow. The film model assumes the film is "thin" relative to the mesh and flow. A film could be a few cm thick in some cases (probably a little extreme) for a roof or the like.
March 29, 2022 at 3:31 pmAnadi_MondalSubscriber
I didn't catch you properly. Here you just told 'it depends on flow', but would you give an example with flow parameters( like air/water Re) and mesh geometry( mesh size in the axial or radial direction, near-wall mesh thickness?
Moreover, you mention 'the film is "thin" relative to the mesh and flow'. What is the comparable mathematical relation for film thickness, mesh and flow for the EWE model?
March 29, 2022 at 3:41 pmRobAnsys EmployeeI don't have fixed numbers, but it's covered here https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v221/en/flu_th/flu_th_ewf_intro.html If there is sufficient mass in the film it will flow against the bulk fluid flow - I've been working on such a problem on and off for a larger project for a couple of years.
Viewing 3 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
- Floating point exception in Fluent
- What are the differences between CFX and Fluent?
- Heat transfer coefficient
- Difference between K-epsilon and K-omega Turbulence Model
- Getting graph and tabular data from result in workbench mechanical
- The solver failed with a non-zero exit code of : 2
- Suppress Fluent to open with GUI while performing in journal file
- Mesh Interfaces in ANSYS FLUENT
- Time Step Size and Courant Number
- error: Received signal SIGSEGV
© 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.