Compact representation of Large Eddy Simulations of the atmospheric boundary layer using proper Orthogonal Decomposition

Studies have been conducted to assess the use of Proper Orthogonal Decomposition to create a database for a low order, compact representation of Large Eddy Simulations of atmospheric boundary layers. In particular, POD analysis of simulations of two extreme cases: a day-time unstable and a night-time stable boundary layer, were conducted. Most notable advantage of using LES, as opposed to spectral based turbulence simulation codes available today, is the ability to model the true flow features, and POD potentially allows to capture these features in a compact manner. The presence of energy containing, large coherent structures in the unstable case allow the decomposition technique to perform efficiently. On the other hand, the absence of these coherent structures in a stable case leads to poor performance of POD, thus, requiring higher number of modes for accurate representation of boundary layer. Nonetheless, the excellent performance of POD for the unstable case is encouraging and POD may prove to be useful for low order representation of other possible boundary layers.