Abstract
A new vortex identification method (Liu et al. 2016) was proposed to represent the rotation relative strength and capture and visualize the vortices in our previous study. The basic idea of the Ω method is that a ratio of the vorticity squared over the summation of the vorticity squared and the deformation squared should be used to measure the relative rotation strength. However, the vorticity tensor norm is not objective. Thus, a moving observer will observe different vortex structures in a moving reference frame, which will make people confused with the real vortex structures. In the present study, by the definitions of the net spin tensor and net vorticity vector, an objective omega vortex identification method is presented and the examples are presented to verify the vortex structures will still retain in a moving reference frame.
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Acknowledgments
This work was supported by the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (Grant Nos.18KJA110001), the Visiting Scholar Scholarship of the China Scholarship Council (Grant No. 201808320079), and the China Post-Doctoral Science Foundation (Grant No. 2017M610876). This work is partly accomplished by using code DNSUTA and LESUTA developed by Dr. Chaoqun Liu at the University of Texas at Arlington, and by using code CABA developed by Dr. Ning Zhao at Nanjing University of Aeronautics and Astronautics.
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Project supported by the National Nature Science Foundation of China (Grant Nos. 91530325, 11702159).
Biography: Jian-ming Liu (1977-), Male, Ph. D., Associate Professor
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Liu, Jm., Gao, Ys., Wang, Yq. et al. Objective Omega vortex identification method. J Hydrodyn 31, 455–463 (2019). https://doi.org/10.1007/s42241-019-0028-y
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DOI: https://doi.org/10.1007/s42241-019-0028-y