March 8, 2022 at 9:39 amGokkulSubscriber
I am doing steady state 3D simulation for turbine. Before assembling the whole turbine, I tried simulating only the first stator. Everything was fine and I was able to get results. But when I am trying after assembling 2 stage turbine, I am getting errors like "Floating point exception: Overflow" or "Fatal Overflow of linear solver" before 10th iterations. So I tried simulating the first rotor alone, I am getting the same error. The mesh analysis has no error and even in the CFX solver, under mesh statistics, everything says OK. I tried using different mesh from coarse to very fine mesh. I can see that only the rotor has the error. I am using SST for turbulence model. The heat transfer model is Total Energy. Also, with the same rotor geometry and mesh, when I tried Air at 25C as fluid the simulation ran without any errors. The error pops up when I use Air as Ideal Gas. That's why it was very confusing and don't know where exactly the problem is! I created backup file before the error and when I was post-processing the results, the magnitude of velocity is too high (1.9e3).
It would be great if someone could assist me in this situation. If needed I can share my mesh file or CFX file.
Thanks in advance!March 8, 2022 at 5:48 pmrfblumenAnsys EmployeeThe error "Floating point exception: Overflow" means that a number is being generated that is too large to store. It could be related to dividing a number by a very small number. Some things to try:
-Review the boundary conditions to make sure they're reasonable
-Run in double precision.
-Try with a smaller time step
In order to understand what's happening in the model, it's helpful to run the model to just before it crashes and look at the solution in CFD-Post. The out file gives minimal information on the cause of the crash - to find out you need to look at the solution. Plot velocity vectors over the entire domain and look where the max vectors are and see why.
If using a massflow outlet, sometimes the massflow is maldistributed at the outlet giving rise to high velocities. To fix this, set the option to constant flux
Viewing 1 reply thread
Ansys Innovation Space
- You must be logged in to reply to this topic.
Simulation World 2022
Check out more than 70 different sessions now available on demand. Get inspired as you hear from visionary companies, leading researchers and educators from around the globe on a variety of topics from life-saving improvements in healthcare, to bold new realities of space travel. Take a leap of certainty and check out a session today here.
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
- Suppress Fluent to open with GUI while performing in journal file
- Heat transfer coefficient
- What are the differences between CFX and Fluent?
- Floating point exception in Fluent
- Time Step Size and Courant Number
- Difference between K-epsilon and K-omega Turbulence Model
- The solver failed with a non-zero exit code of : 2
- Floating point exception
- Exporting Data Results
Top Rated Tags