Pressure drop fluctuates

- March 3, 2022 at 2:23 am
  
  btingthewind
  Subscriber
  
  Dear you,
  Now I am doing a steady state simulation in Fluent with pressure based solver.
  Boundary condition:
  Velocity inlet (Velocity 10 m/s, Reynolds number 4000), pressure outlet, and other sides are periodic and symmerty.
  Mesh quality:
  Minimum orthogonoal 0.2.
  Turbulence model:
  RNG ke with enhanced wall treatment.
  Pressure drop is defined as:
  Static pressure of (the inlet - outlet).
  
  My question is:
  Why the pressure drop fluctates in a sinoidal pattern with in a range of 2 Pa, even the residuals of continuity and so on below 1e-5?
  
  BEST REGARDS
- March 3, 2022 at 12:04 pm
  
  Murari Iyengar
  Ansys Employee
  
  Hi btingthewind This could happen due to a couple of reasons.
  High mesh skewness/aspect ratio: Please look through Chapter 22: Improving the Mesh (ansys.com).
  Incorrect model: Maybe K-e is not the correct model for your simulation. Try other turbulence models. Also, the Re is 4000 which indicates a mix of laminar and turbulent flow (I'm assuming you are doing internal flow). This could also be a reason for fluctuating residuals since the flow might not be steady.
- March 3, 2022 at 12:07 pm
  
  Rob
  Ansys Employee
  
  Please can you post some images? Depending on the pressure 2Pa could be near enough zero change or huge.
- March 5, 2022 at 11:56 pm
  
  btingthewind
  Subscriber
  
  Many thanks to you!!
- March 5, 2022 at 11:57 pm
  
  btingthewind
  Subscriber
  
  Many thanks to you!!

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