Rotation of the velocity measurements: Difference between revisions
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The [[frame of reference|measurement frame of reference]] varies between set-ups. In some instances, the instrument has an axis aligned with the direction of flow, which is ideal to account for the varying levels of anisotropy amongst components <ref name=" | The [[frame of reference|measurement frame of reference]] varies between set-ups. In some instances, the instrument has an axis aligned with the direction of flow, which is ideal to account for the varying levels of anisotropy amongst components <ref name="Gargett.etal1984">{{Cite journal | ||
|authors= A. E. Gargett, T. R. Osborn, and P.W. Nasmyth | |authors= A. E. Gargett, T. R. Osborn, and P.W. Nasmyth | ||
|journal_or_publisher= J. Fluid. Mech. | |journal_or_publisher= J. Fluid. Mech. | ||
Revision as of 13:28, 5 July 2022
The measurement frame of reference varies between set-ups. In some instances, the instrument has an axis aligned with the direction of flow, which is ideal to account for the varying levels of anisotropy amongst components [1]. Still, it's possible to rotate the measurements into the main component of the flow if intending on making use of the different components when estimating [math]\displaystyle{ \varepsilon }[/math] or other turbulence quantities (e.g., Reynold stresses). If one intends on using only the vertical velocity component to estimate [math]\displaystyle{ \varepsilon }[/math], then this step of rotating the velocity measurements may be skipped. Mention anisotropy, and refer to my own paper
Methods used for rotating into the analysis frame of reference
We will update when our final recommendation is set in stone. Also, comment about large vertical velocities on sloped bottoms...
- Using time-averaged velocities in each segment
- Principal component analysis
References
- ↑ A. E. Gargett, T. R. Osborn and and P.W. Nasmyth. 1984. Local isotropy and the decay of turbulence in a stratified fluid. J. Fluid. Mech.. doi:10.1017/S0022112084001592
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