A simple technique for the visualisation of eddy kinematics in turbulent flows

作者：Lee Geoffrey; Scalo Carlo^*; Piomelli Ugo

来源：International Journal of Computational Fluid Dynamics, 2012, 26(4): 263-274.

DOI：10.1080/10618562.2012.693605

• flow visualisation
• large-eddy simulation
• turbulent structures kinematics
• Structural Similarity Index
• advective interpolation
• movie accuracy and smoothness
• human visual system

We developed and tested a simple technique to predict, for flow visualisation purposes only, the evolution of coherent structures in between two given realisations of a turbulent flow. Classic coherent-structure eduction methods are adopted, such as the Q-criterion, pressure fluctuations and contours of velocity fluctuations. The kinematics of the evolving structures are reconstructed by means of an advection-based reconstruction technique and captured in a movie. The resulting quality of the animations has been assessed via the Structural Similarity Index (SSIM). The sensitivity to increasing spacing in time of the available flow realisations has been tested and several improvements implemented. The abrupt transition from reconstructed frames of the animation to the available realisations results in a noticeable lack of smoothness. The replacement of the available realisations with a similar advection-based average increases the perceived smoothness of the movies. This is confirmed by the reduced total variation of the SSIM index. The residual minor periodic variations of accuracy have been reduced by introducing a stochastic weighting function. The sensitivity of the results to changes in Reynolds number, resolution and structure representation methods has been tested.

• 出版日期2012