Modeling orographic flows on unstructured meshes Piotr Smolarkiewicz, National Center for Atmospheric Research*, USA; Joanna Szmelter, Loughborough University, United Kingdom * The National Center for Atmospheric Research is supported by the National The National Center for Atmospheric Research is supported by the National Science Foundation Science Foundation
Modeling orographic flows on unstructured meshes Piotr Smolarkiewicz , National Center for Atmospheric Research*, USA; Joanna Szmelter , Loughborough University, United Kingdom. * The National Center for Atmospheric Research is supported by the National Science Foundation. - PowerPoint PPT Presentation
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Modeling orographic flows on unstructured meshes
Piotr Smolarkiewicz, National Center for Atmospheric Research*, USA; Joanna Szmelter, Loughborough University, United Kingdom
**The National Center for Atmospheric Research is supported by the National Science The National Center for Atmospheric Research is supported by the National Science Foundation Foundation
NCAR
The twofold aim of this talk:
highlight the progress with the development of a nonhydrostatic, soundproof, unstructured-mesh model for atmospheric flows;
assess the accuracy of unstructured-mesh discretization relative to established structured-grid methods for orographic flows;
NCAR
EULAG’s key features(www.mmm.ucar.edu/eulag/)
• A suit of governing PDEs;
numerical laboratory
• Conservative, nonoscillatory,
forward in time (NFT) semi-
implicit numerics
• Robust elliptic solver; “exact
projection”
• Static /dynamic grid stretching
with 2nd order accuracy
Cloud cover and precipitation over the Alps
Gray and blue volumes denote cloud water and rainfall, respectively.
NCARUnstructured-mesh framework for
atmospheric flows Smolarkiewicz Szmelter, pubs in JCP, IJNMF,Comp. Fluids, 2005-2011
• Differential manifolds formulation
• Finite-volume NFT numerics with a fully unstructured spatial discretization, heritage of EULAG and its predecessors (A = MPDATA)
• Focus (so far) on wave phenomena across a range of scales and Mach, Froude & Rossby numbers
Comparison with the EULAG’s results and the linear theories (Smith 1979, Durran 2003): 3% in wavelength; 8% in propagation angle; wave amplitude loss 7% over 7 wavelenghts