Fourier-Ray Modeling of Transient Trapped Lee Waves

Abstract

The Fourier-ray method involves ray tracing in a Fourier-transform domain. The ray solutions are then Fourier synthesized to produce a spatial solution. Here previous steady-state developments of the Fourier-ray method are extended to include a transient source of mountain waves. The method is illustrated with an initial value problem in which the background flow is started abruptly from rest and then maintained at steady velocity. The resulting wave transience is modeled in a simple way. All rays that radiate from the mountain, including the initial rays, are assigned the full amplitude of the longtime steady-state solution. Time dependence comes in through the changing position of the initial rays. This is sufficient to account for wave transience in a test case, as demonstrated by comparison with simulations from a mesoscale numerical model.

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Document Details

Document Type
Technical Report
Publication Date
Oct 01, 2006
Accession Number
ADA573659

Entities

People

  • Dave Broutman
  • John Lindeman
  • Jun Ma
  • Stephen D. Eckermann

Organizations

  • United States Naval Research Laboratory

Tags

Communities of Interest

  • Space

DTIC Thesaurus Topics

  • Amplitude
  • Boundaries
  • Boundary Layer
  • Computational Science
  • Equations
  • Frequency
  • Gravity Waves
  • Military Research
  • Mountains
  • Peak Values
  • Phase Shift
  • Ray Tracing
  • Simulations
  • Steady State
  • Time Dependence
  • Wave Propagation
  • Wind

Fields of Study

  • Physics

Readers

  • Fluid Dynamics.
  • Occupational Health and Safety.
  • Seismology