What is the difference between the field flow: velocity and a contour plot of velocity?

- December 4, 2020 at 11:46 am
  
  psayasith
  Subscriber
- December 4, 2020 at 3:25 pm
  
  KR
  Administrator
  
  HinWhich tool are you using to get these results?nWhat are the boundary conditions you use in the two simulations? Is it the same pipe dia and length (same geometry and mesh)?nKarthikn
- December 4, 2020 at 3:32 pm
  
  psayasith
  Subscriber
  
  I'm using discovery aim to do a fluid flow simulation. The boundary conditions are an inlet of 4.59 * 10^-5 kg/s and an outlet of 62.5 m/s. It's the exact same pipe in both. I did solve physics and when I evaluated the results, the second image was the default display when I clicked results in work flow and the first image is when I then created a contour plot of the velocity magnitude. Both are listed as showing velocity magnitude in the software. n
- December 4, 2020 at 8:07 pm
  
  DrAmine
  Ansys Employee
  
  Mass flow at inlet and velocity outlet is completely wrong here. System overpredicted. Use pressure boundary. What do you want to do here?n
- December 4, 2020 at 10:40 pm
  
  psayasith
  Subscriber
  
  Mass flow at inlet and velocity outlet is completely wrong here. System overpredicted. Use pressure boundary. What do you want to do here?https://forum.ansys.com/discussion/comment/99390#Comment_99390
  I realize now I calculated those values based upon the flow being incompressible. My end goal is to simulate a gas flow of nitrogen and input the pressure and velocity into another program to run in conjunction with an electric field. Here, I was trying to get the gas flow conditions I wanted in a basic pipe shape before moving on to a more complex shape. This is my first time using any software for fluid flows, so the whole thing is very much a learning process for me. nIs the field flow: velocity and the contour plot of velocity being different indicative of the system overpredicting? I saw these two different results for the same solve physics and was trying to figure out why they were different. nThank you. n
- December 7, 2020 at 1:10 pm
  
  KR
  Administrator
  
  Hello,nAs mentioned by you should not be using the mass flow inlet and velocity outlet conditions. You are over-specifying the system. Please use pressure outlet instead of velocity outlet. This is the correct way of modeling pipe flow, especially for incompressible flows.nThanks.nKarthikn

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