Weird phenomenon on Trnavg results ?

- April 30, 2022 at 2:07 pm
  
  mona2022
  Subscriber
  
  Hi all,
  I am doing a transient simulation with a need to get the time averaged velocity field using the "arithmetic average" set in CFX-Pre.
  But, when I check the time average results, I have found that for the nearly unchanged transient velocity profile which was extracted far upstream from the separation bubble and thus remains almost steady there (which has been checked from the transient data), its resulted time-averaged profile differ greatly from it.
  In particular, unlike the transient one which is smooth, the time-averaged profile oscillates a lot and is, further more , discontinuous along the normal direction (y) . This phenomenon can be found from the attached figures called "u_trnavg changes" and "u_unchange".
- May 11, 2022 at 4:30 pm
  
  Surya Deb
  Ansys Employee
  
  Hello,
  It seems like you are using the "Velocity" variable as a vector for the Output control. Is that correct? Do you want to average the velocity magnitude or velocity along a specific coordinate?
  Regards SD
- May 11, 2022 at 5:06 pm
  
  mona2022
  Subscriber
  
  Hi sdeb I want to average the velocity along each coordinates, namely velocity u, velocity v and velocity w, in order to get the mean velocity field.
  With using "Velocity" as a vector in this transient statistics, I got the "Velocity u.Trnavg", "Velocity v.Trnavg" and "Velocity w.Trnavg" respectively, which I think is the very thing I need.
  Is there something wrong with my above operation which you think has resulted in this weird phenomenon?
  Look forward to your replying and thank you in advance!
  Best regards Mona.
- May 11, 2022 at 11:47 pm
  
  Surya Deb
  Ansys Employee
  
  Hello,
  The operation looks all right to me. Can you double check the start iteration?
  Also check the smoothness at other locations as well.
  Do you see any dependence on mesh resolution?
  Regards SD

Viewing 3 reply threads

You must be logged in to reply to this topic.

Ansys Innovation Space

SimACE-23

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.

Ansys Blog

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