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The cast of this episode: Oliver Fringer and Bob Street

HOW AESOP GOT A SUNTAN A fractured fairy tale (with apologies to the producers of the Rocky and Bullwinkle show). The cast of this episode: Oliver Fringer and Bob Street Environmental Fluid Mechanics Laboratory at Stanford University Synopsis: The context and collaborators

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The cast of this episode: Oliver Fringer and Bob Street

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  1. HOW AESOP GOT A SUNTANA fractured fairy tale(with apologies to the producers of the Rocky and Bullwinkle show) • The cast of this episode:Oliver Fringer and Bob Street • Environmental Fluid Mechanics Laboratory at Stanford University • Synopsis: • The context and collaborators • The tools and some pretty pictures • Some thoughts on our work plan 8 March 2005

  2. The context: we are participating in AESOP and in NLIWI. Our overall goals include collaboration with UCLA to support the continuing development of our models, SUNTANS and ROMS; their coupling; and the scientific issues to be set forth by the ONR NLIWI and AESOP DRI experiments. Our collaborators: Jim McWilliams, Sasha Shchepetkin, Yulia Kanarska, UCLA

  3. Our Tools • SUNTANS - a free-surface NS simulation code for the coastal ocean. Currently implemented for Monterey Bay applications. • LES - tools for the large-eddy simulation of the flows, including subfilter models that parameterize the unresolved motions.

  4. SUNTANS Overview • SUNTANS: • Stanford • Unstructured • Nonhydrostatic • Terrain-following • Adaptive (not yet) • Navier-Stokes • Simulator • Parallel computing • Large-eddy simulation

  5. High-resolution simulations must be nonhydrostatic Hydrostatic Nonhydrostatic Doman size: 0.8 m by 0.1 m (grid: 400 by 100)

  6. Simulation results using 500 m grid + MY2.5 north-south velocity contours. Max velocity = 5 cm/s

  7. Along-canyon generation sites Comparison of results to measurements Of Petruncio, et al. (1998,2002)

  8. Cross-canyon generation sites Comparison of results to measurements Of Lien and Gregg (2001)

  9. LES Overview • Work based on decomposition of flow into resolved and subfilter motions by spatial filtering. Subfilter scales are further separated into • resolved subfilter scales [computational grid size is at least a factor of 2 smaller than spatial filter size]. Highly accurate representation possible; facilitates energy transfer to and from large scales. • subgrid scales. These must be modeled. • These ideas have been proven and are being introduced in to SUNTANS. SUNTANS currently employs a RANS approach with, e.g., Mellor-Yamada 2.5 closure.

  10. RSFS and SGS scale partitioning • Resolved scales • Well-resolved • Resolved subfilter scales (RSFS) • Can be reconstructed • Subgrid scales (SGS) • Must be modeled • Numerical Errors (NE) • Limit reconstruction

  11. Improvements near the wall as applied to a neutral boundary layer in the atmosphere. Smagorinsky Dynamic eddy viscosity + Near-wall model Dynamic reconstruction + Near-wall model Log law

  12. Thoughts on contributions to DRI • High-resolution nonhydrostatic modeling of Monterey Bay (up to 10 m resolution) can be made available, i.e., simulation of scales from regional to those at which mixing takes place. • Simulated cruise tracks • Prediction and refinement via direct comparison to actual cruise tracks • Basis for evaluation of coarser resolution simulations and their parameterizations. • Boundary forcing for domains of simulators working on small scales. • Evaluation of RANS and LES turbulence models [ours and those of others] at submesoscale [100 m and up resolutions]. • Nesting of SUNTANS into ROMS and follow-up simulations to assess value of high resolution in specific areas and how that impacts submesoscale parameterizations.

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