J0101-1-1 Complexity Representation of Turbulent Velocities Using Data Compression

Abstract

In order to indicate the complexity of signals in turbulent flows quantitatively, we used a concept of Kolmogorov complexity in computational science. The velocity data was compressed with the use of software for compression. The ratio of data size after compressed one to original one reflects the complexity of the data. Thus we named the ratio "Approximated Kolmogorov Complexity(AK)". First, we checked the validity of AK as the representation of complexity with the aid of simple data. The difference of AK among three compression methods was tested. Then, the present analysis was applied to the laminar-turbulent transition process in a boundary layer. In turbulent region AK showed larger values, on the other hand, in laminar region AK showed smaller values. The existence of a coherent structure close to the wall was suggested.