Fast and Robust Extraction of Separation Line Features

The visualization of a three-dimensional viscous flow around an embedded object is typically based on the analysis of its wall shear stress. This vector field defined over the object body exhibits structures that are key to the qualitative evaluation of the surrounding flow. Open separation and attachment lines are of essential interest in aerodynamics due to their adverse effects on the object motion and their implication in vortex genesis. The paper presents a new method for the efficient analysis and visualization of separation and attachment lines on polyhedral surfaces in threespace. It combines local prediction and global feature extraction to yield a scheme that is both efficient and accurate. In particular, it does not suffer from the restrictions induced by assumptions of local linearity and is able to detect features where existing techniques fail. The algorithm is built upon an efficient streamline integration scheme on polyhedral surfaces. The latter is also employed to develop a variation of the LIC scheme. Results are proposed on CFD data sets that demonstrate the ability of the new technique to precisely identify and depict interesting structures in practical applications.