3D iso-contour of swirling strength (vorticity) in channel

An example of visualising an instantaneous vorticity field in channel flow. The vorticity field is calculated using swirling strength.

This code serves as an example of plotting the vorticity field of an instantaneous channel flow snapshot. The vorticity field is calculated using swirling strength (see the original paper: Chong, M., Perry, A. & Cantwell, B. A general classification of three-dimensional flow fields. Phys. Fluids A, 2, 765-777 (1990)). The channel size is 2\pi by \pi by 2 (streamwise length, spanwise length, wall-normal length).

The iso-contour value of the swirling strength could be changed by modifying variable ‘iso_percentage’ in the main code ‘MAIN_swirling_strength.m’.

There are six snippets: 'MAIN_swirling_strength.m', 'get_swirling_strength.m', 'get_velocity_tensor.m', 'get_km.m', 'get_3d.m' and 'cheb.m'. There is one dataset for the instantaneous velocity field: 'velocity_for_swirling_strength.mat'.

To run the code, put all the files inside a same folder. Open the code 'MAIN_swirling_strength.m', click 'Run' under 'EDITOR'. You will obtain a figure same as the profile photo.

Please download the zip file to get the dataset 'velocity_for_swirling_strength.mat' which cannot be shown on the webpage.