Slip Boundary Formulation for Low-Pressure System

- October 31, 2018 at 8:04 am
  
  Devank12
  Subscriber
  
  can any one explain me how to create slip boundary formation for above mentioned low pressure (<0.01 Pa)concentric tube?
- October 31, 2018 at 9:13 am
  
  seeta gunti
  Ansys Employee
  
  Hi,
  
  Slip boundary can be given if you define the boundary as wall.
  
  Can you elaborate more on your problem description and objective of the study for better understanding.
  
  Regards,
  
  Seeta
- October 31, 2018 at 9:52 am
  
  Devank12
  Subscriber
  
  i am currently analysing flow through a concentric pipe using fluent. inner and outer pipes are made by copper and borosilicate glass respectively. the water flow inside the pipe is laminar. The space between the inner tube and outer cover tube made by vacuum (< 0.01Pa). i need to create a vacuum zone in the annulus gap.
- November 1, 2018 at 11:57 am
  
  Rob
  Forum Moderator
  
  A useful approach for the vacuum section is to model it as a solid and adjust the conductivity to near enough zero: look up the Knudsen Number for continuum flow. You'll need to allow it to participate in radiation calculations otherwise the (I assume) solar energy won't get to the inner tube.