April 18, 2023 at 6:28 amMathias GiesbrechtSubscriber
I am currently working on a transient thermoelectric simulation for a fuse in a power distribution unit. The simulation ambient temperature is set at 60 degrees Celsius, and the range boundary condition for convection is also set at 60 degrees Celsius. However, during the simulation, I have noticed that the temperature inside the fuse drops below 60 degrees Celsius, even when the current is still flowing through it.
I have attached a photo of the problematic part of the simulation for your reference, and I would appreciate any feedback or recommendations on how to solve this issue. I am open to any insights that could help me understand and address the problem, including possible improvements to my simulation setup or approaches to analyze the simulation results.
April 20, 2023 at 2:28 pmDave LoomanAnsys Employee
It could be because the elements are too large for the time step. In Section 220.127.116.11 of the APDL Thermal Analysis Guide there's an equation that says the time step cannot be greater than:
(element size)^2 / 4*diffusivity.
This is for second order elements. You could try switching to first order elements.
April 20, 2023 at 3:18 pmMathias GiesbrechtSubscriber
Thanks for the help! Does the programm can not separate himself in smaller substep during the calculation?
I created a smaller version of the simulation, and now the temperature no longer drops below the ambient temperature. However, I still don't understand how the system works with different time steps. When I use more time steps, the system heats up quickly in the first 2-3 steps and then gradually becomes hotter over the next 7 steps. On the other hand, if I use only 2-3 time steps, the system heats up more slowly.
The screenshot below are for the same model and all the paramter are constant.
Thanks for the help
April 20, 2023 at 4:27 pmDave LoomanAnsys Employee
Could you email me those images at firstname.lastname@example.org ? They're hard to read in the forum. I can't explain why solving in 2 or 3 steps would slow the heating. The time integration might not be as accurate and if the loading is ramped it might be ramped over a longer time, but those two effects wouldn't make a huge difference. A factor of 2 in the heating rate at most.
- 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.
- Solver Pivot Warning in Beam Element Model
- Saving & sharing of Working project files in .wbpz format
- Understanding Force Convergence Solution Output
- An Unknown error occurred during solution. Check the Solver Output…..
- What is the difference between bonded contact region and fixed joint
- User manual
- The solver engine was unable to converge on a solution for the nonlinear problem as constrained.
- whether have the difference between using contact and target bodies
- material damping and modal analysis
- Colors and Mesh Display
© 2023 Copyright ANSYS, Inc. All rights reserved.