Numerical Studies of Three-Dimensional Turbulence in Small Aspect Ratio Domains

点击翻译按钮获取中文摘要

CTS-9528491 Smith This is a study of three dimensional turbulence in small aspect ratio (SAR) domains, where the vertical height, H, is small compared to the length, L, in the horizontal direction. The objective is to solve the incompressible Navier Stokes equations using a pseudo-spectral code in a periodic domain for varying resolutions. The study will be aimed at bridging the gap between turbulence research and geophysical applications. Of special interest is the transition from two dimensional to three dimensional turbulence and related fundamental issues such as the change in the energy cascade. Two-dimensional turbulence is characterized by an inverse cascade of energy to large scales whereas the direction of the energy flux in three-dimensional turbulence is in the direction of smaller scales. The interest in the SAR domain is the apparent lack of detailed study in spite of the relevance to geophysical phenomena such as atmospheric turbulence. One of the unique features of this study is to consider SAR turbulence where the vertical velocity is not small in comparison to the horizontal turbulence at small scales. this would allow the modeling of phenomena that are inaccessible to quasi-geostrophic models, such as atmospheric large scale motions that are partially driven by vertical convection at relatively small scales. The interaction of coherent structures with background forcing in SAR domains is one of the objectives of the research. The research addresses an important aspect of turbulence dynamics that has not received adequate attention in the past. The results of this research will have an important impact on our ability to predict geophysical flows.