Vortex identification: New requirements and limitations

@article{citeulike:1465350, abstract = {Firstly, a brief survey dealing with popular vortex-identification methods is presented. The most widely used local criteria (applied point by point) - sharing a basis in the velocity-gradient tensor [backward difference]u - are treated more thoroughly to recall their underlying ideas and physical aspects. A large number of recent papers have pointed out various applicability limitations of these popular schemes and formulated (explicitly or implicitly) new general requirements, for example: validity for compressible flows and variable-density flows, determination of the local intensity of swirling motion, vortex-axis identification, non-local properties, ability to provide the same results in different rotating frames, etc. Other quite natural requirements are pointed out and added to those already mentioned. Secondly, the vortex-identification outcome of the proposed triple decomposition of the relative motion near a point is presented. The triple decomposition of motion - based on the extraction of a so-called "effective" pure shearing motion - has been motivated by the fact that vorticity cannot distinguish between pure shearing motions and the actual swirling motion of a vortex. This decomposition technique results in two additive vorticity parts (and, analogously, in two additive strain-rate parts) of distinct nature, namely the shear component and the residual one. The residual vorticity represents a direct measure of the actual swirling motion of a vortex. The new kinematic vortex-identification method is discussed on the background of previous methods and general vortex-identification requirements (illustrative examples are included).}, author = {Kolar, Vaclav }, booktitle = {Including Special Issue of Conference on Modelling Fluid Flow (CMFF'06), Budapest, 13th event of the international conference series in fluid flow technologies: conference on modelling fluid flow}, citeulike-article-id = {1465350}, journal = {International Journal of Heat and Fluid Flow}, keywords = {classification, coherent-structures}, month = {August}, number = {4}, pages = {638--652}, posted-at = {2007-07-18 18:24:38}, priority = {2}, title = {Vortex identification: New requirements and limitations}, url = {http://www.sciencedirect.com/science/article/B6V3G-4NT93VN-1/2/bc1f7ab8bc96f31c431cea306dbd0951}, volume = {28}, year = {2007} }

TY - JOUR ID - citeulike:1465350 L3 - citeulike-article-id:1465350 TI - Vortex identification: New requirements and limitations T2 - Including Special Issue of Conference on Modelling Fluid Flow (CMFF'06), Budapest, 13th event of the international conference series in fluid flow technologies: conference on modelling fluid flow JF - International Journal of Heat and Fluid Flow VL - 28 IS - 4 SP - 638 EP - 652 N2 - Firstly, a brief survey dealing with popular vortex-identification methods is presented. The most widely used local criteria (applied point by point) - sharing a basis in the velocity-gradient tensor [backward difference]u - are treated more thoroughly to recall their underlying ideas and physical aspects. A large number of recent papers have pointed out various applicability limitations of these popular schemes and formulated (explicitly or implicitly) new general requirements, for example: validity for compressible flows and variable-density flows, determination of the local intensity of swirling motion, vortex-axis identification, non-local properties, ability to provide the same results in different rotating frames, etc. Other quite natural requirements are pointed out and added to those already mentioned. Secondly, the vortex-identification outcome of the proposed triple decomposition of the relative motion near a point is presented. The triple decomposition of motion - based on the extraction of a so-called "effective" pure shearing motion - has been motivated by the fact that vorticity cannot distinguish between pure shearing motions and the actual swirling motion of a vortex. This decomposition technique results in two additive vorticity parts (and, analogously, in two additive strain-rate parts) of distinct nature, namely the shear component and the residual one. The residual vorticity represents a direct measure of the actual swirling motion of a vortex. The new kinematic vortex-identification method is discussed on the background of previous methods and general vortex-identification requirements (illustrative examples are included). KW - classification KW - coherent-structures AU - Kolar, Vaclav PY - 2007/08// UR - http://www.sciencedirect.com/science/article/B6V3G-4NT93VN-1/2/bc1f7ab8bc96f31c431cea306dbd0951 ER -