Tagged: Discovery Live
July 1, 2019 at 7:01 amlars.hanschmannSubscriber
I have assigned new boundary conditions to every outer face in a thermal problem.
But the defaults Ambient Temperature / Convection in Air are still present and both have faces assigned.
How can I manage to get rid of these assignments?
July 1, 2019 at 10:28 amGaurav SharmaSubscriber
The ambient definition (coefficient and ambient temperature) is used to calculate convective heat transfer. By default any thermal setup has this convection BC and if user wants to get rid of it, you can simply use 0 as the convection coefficient and this should make the default BC redundant. Unfortunately, deleting this BC doesn't appear possible.
While I tried and found this workaround to be working well for me, please let me know if you are having some unexpected observations with this approach.
July 2, 2019 at 5:30 amlars.hanschmannSubscriber
it is not the point to set the BC to 0. I have assigned other BC for all faces to the outside. But there are still faces assigned to the default ambient definition. By the way wouldn't we receive an adiabatic BC if we set the film coefficient to be 0?
July 2, 2019 at 6:55 amGaurav SharmaSubscriber
The ambient temperature is the temperature of space surrounding the component. It doesn't enforce a temperature condition at any surface. Once you apply any BC to your model, say temperature, this will govern the behavior and the ambient temperature will only be used to calculate convective heat transfer.
In order to control the convective heat transfer, you can set a 0 convection coefficient. This would mean no heat transfer using default BC, but any other convection BC applied to this surface would still act and this approach does NOT enforce any adiabatic condition.
In a nutshell, zero convection coefficient only suppresses the default BC (as good as deleting the BC altogether) and the ambient temperature (which is used to calculate heat transfer) doesnt play any further role. So even if there are faces you see assigned to ambient temperature, it shouldn't be a problem since the faces are not forcefully assigned this temperature. Further, a zero coefficient does ensure no heat transfer through this surface using default BC.
I hope that answers your query.
- 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.
© 2023 Copyright ANSYS, Inc. All rights reserved.