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Fixes to Omega v1 Governing Equations#326

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xylar merged 4 commits intoE3SM-Project:developfrom
xylar:omega/docs/fix-omega-v1-equations
Feb 23, 2026
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Fixes to Omega v1 Governing Equations#326
xylar merged 4 commits intoE3SM-Project:developfrom
xylar:omega/docs/fix-omega-v1-equations

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@xylar xylar commented Dec 15, 2025

This pull request updates the documentation in OmegaV1GoverningEqns.md to improve the consistency, clarity, and correctness of the mathematical notation used in the derivation of the governing equations. The changes primarily remove unnecessary factors of \rho_0 from several equations, clarify the definition and notation for surface forces, and correct integration limits and variable usage for consistency.

Mathematical and Notational Corrections:

  • Removed unnecessary factors of \rho_0 from the pseudo-height mass, tracer, and momentum conservation equations, as well as from their layer-averaged and Reynolds-averaged forms, to ensure dimensionally consistent and simplified expressions. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10]

  • Clarified the definition of the surface force (traction vector) as \tau = \sigma \cdot {\bf n} and distinguished the horizontal component \tau_\perp in the momentum equation, improving the physical interpretation and accuracy of boundary force terms. [1] [2]

Consistency and Integration Limit Corrections:

  • Corrected integration limits and variable usage in the layer and Reynolds-averaged tracer equations to ensure consistency with the rest of the document and the intended physical meaning.

  • Updated several equations to use consistent notation for averages, fluctuations, and layer integrals, improving readability and reducing the risk of confusion. [1] [2] [3] [4] [5] [6]

Checklist

  • Documentation:
    • Documentation has been built locally and changes look as expected

@xylar xylar requested a review from hyungyukang December 15, 2025 14:42
@xylar xylar self-assigned this Dec 15, 2025
@xylar xylar added bug Something isn't working documentation Improvements or additions to documentation Design labels Dec 15, 2025
@xylar xylar mentioned this pull request Dec 15, 2025
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xylar commented Dec 15, 2025

@sbrus89, this doesn't include the other fixes to the HPGF we have discussed. That would follow up on these fixes.

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@xylar , thanks a lot. I was also planning to fix the same places for \rho_0 and \tau. I will review soon.

@xylar xylar force-pushed the omega/docs/fix-omega-v1-equations branch from 266ff68 to 8545c0c Compare February 23, 2026 11:39
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Approved based on visual inspection (the compiled version is available here: https://users.nccs.gov/~hgkang/omega/omega_xylar/design/OmegaV1GoverningEqns.html).

Thanks, @xylar! The document has improved significantly. I think this PR and #326 can be merged into develop first and open another PR later if additional updates are needed.

Surface flux terms, body forces and pressure terms were all getting
multiplied by $\rho_0$, leading to incorrect dimensions and
inconsistency with the rest of the derivation.
@xylar xylar force-pushed the omega/docs/fix-omega-v1-equations branch from 8545c0c to 4d2feb2 Compare February 23, 2026 19:20
@xylar xylar merged commit 3a32261 into E3SM-Project:develop Feb 23, 2026
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@xylar xylar deleted the omega/docs/fix-omega-v1-equations branch February 23, 2026 19:24
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