A new flow analysis technique: Fourier-Averaged Navier-Stokes equations

• Author / Creator

  Freeman, Benjamin R.S.

• This dissertation introduces a new flow analysis technique based on the Fourier-Averaged Navier-
  Stokes (FANS) equations. It details their application to educing the effect of fluid forces on flow
  physics. The derivation and interpretation of the method is described, and details of how to
  calculate key terms are presented. The method is then applied to several case studies to illustrate
  its applicability, interpretability, and limitations across flows of different complexities. Three of
  these case studies are used to evaluate the characteristics of FANS and verify that the method is
  interpretable. Specifically, conclusions are made from FANS and these conclusions are compared
  to known physics and the findings of other methods. These cases consist of 2D laminar vortex
  shedding over a square cylinder, axisymmetric swirling jet flow, and irregular asymmetric vortex
  shedding over a pair of square cylinders. FANS is shown to be simple to calculate and easy
  to interpret for analysing fluid flows with increasing complexity, including cases with broadband
  spectrum. The final case study looks at 3D flow over normally-oriented, thin flat plates. This case
  illustrates the practicality of FANS in exploring unknown physics in a fully 3D, nonperiodic flow.
  Three flat plates with varying end conditions are compared to investigate the effect of end plates on
  the fluctuating and mean flow. FANS shows the effect of friction from the end plates on dampening
  transverse velocity fluctuations. It also shows how interaction between the rollers with the boundary
  layer induces coherent spanwise flow at the shedding frequency. Overall, the proposed method is
  shown to be applicable in investigating the physics of flows with cyclic characteristics, including
  those with nonperiodic behaviour.

• Subjects / Keywords

  • Computational Fluid Dynamics
  • turbulence
  • Navier-Stokes Equations

• Graduation date

  Spring 2023

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-15wr-wx04

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.