Accession Number : ADA311124

Title :   Nonlinear Dynamics of Internal Waves in the Atmosphere.

Descriptive Note : Final rept. 1 Jan 92-29 Feb 96,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF MECHANICAL ENGINEERING

Personal Author(s) : Akylas, Triantaphyllos R.

PDF Url : ADA311124

Report Date : 18 JUL 1996

Pagination or Media Count : 3

Abstract : A theoretical study was made of the nonlinear dynamics of stratified flow past finite-amplitude topography, as a model for the generation of internal wave disturbances by wind in the atmosphere. An approximate analytical theory was used to study the long time development of finite amplitude disturbances, in an effort to understand the conditions under which steady state is reached and whether transient wave breaking (flow inversions) is possible. A new kind of instability was discovered that sets in at topography amplitudes well below the critical amplitude required for breaking to occur; this instability grows at the expense of the mean flow. In the presence of instability, the flow is transient, fluctuating about the theoretically predicted steady state. There is no significant upstream influence, and no evidence of transient wave breaking was found. These results are consistent with laboratory experimental observations for moderate topography amplitudes.

Descriptors :   *WIND SHEAR, *SKIN FRICTION, TRANSIENTS, OBSERVATION, TOPOGRAPHY, NONLINEAR SYSTEMS, STRATIFICATION, INTERNAL WAVES.

Subject Categories : Meteorology
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE