×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Pressure Boundary Condition problem

Pressure Boundary Condition problem

Pressure Boundary Condition problem

(OP)
Hi,

I'm a relatively new Floworks user and am having some trouble setting pressure boundary conditions. The goal is to analyze the effects of a sampler pulling air in at a much lower speed than the air it is sampling from. Thus far, I have set up rectangular box (0.1m x 0.03m x 0.03m) to simulate ideal outside conditions. It has a velocity inlet at one end of the long side, a total pressure boundary (set to the total pressure based on the inlet velocity) at the opposite end and ideal walls on the other 4 sides. We are using very ideal conditions: laminar flow, non-fully developed tube flow for the inlet, and no gravity. I ran tests just to check this setup was ok before moving on, and realized that my pressure boundary was not staying at the pressure I set it to. When I run a case with the inlet set to 50m/s and the total pressure at 102809Pa, the pressure at the boundary begin a the right pressure, but at the end (about 0.02s real time) don't get over 101500Pa. The pressure in the majority of the domain is 101378-101398. And as the flow gets closer the pressure boundary, the pressure begins to decrease in the corners. I guess I just don't understand why the pressure boundary or the inlet don't have pressures near the total pressure? Is my box not long enough for the velocity? I assumed since our conditions are so ideal, the size wouldn't be a factor.  I also assumed that since it was so short, the flow would reach steady state pretty soon. Should I let it run out longer? Any suggestions would be greatly appreciated!

Thanks,
Shelley

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources