process modes

Match tracking ridge curves across neighboring beta cases and build separate surfaces for each matched mode:

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lst-tools process tracking --maxima
lst-tools process modes
lst-tools process modes --dir /path/to/cases --out mode_surfaces
lst-tools process modes --nx 1000
lst-tools process modes --force

The default input directory is the current directory. Relative output paths are resolved inside it. A nonempty output directory is not overwritten unless --force is supplied; forced processing replaces that output directory.

The command reads nfac_max_mode_*/kc_*.dat and alpi_max_mode_*/kc_*.dat separately. It matches adjacent-beta ridges by frequency agreement over their common streamwise range, not by their local mode_001/mode_002 folder numbers. Weak-overlap and ambiguous matches become new mode IDs instead of being forced together. Matching for N-factor and alpha-imaginary ridges is independent. N-factor ridge extraction and envelope selection both maximize Nfac3; the other N-factor definitions remain available as corresponding output fields.

Each nfac_max_mode_*.dat or alpi_max_mode_*.dat output is a Tecplot ordered (s, Beta) surface containing every source-ridge quantity, including frequency, real and imaginary alpha, amplitudes, N-factors, and Reynolds-number scalings, plus a valid mask. Both families use the same uniform 500-point s grid spanning the source curves' combined minimum and maximum; --nx changes its resolution. Matching is performed on the original ridge coordinates before this output interpolation. Beta remains at the computed case values, without interpolation. Values outside observed ridge segments are zero-filled with valid = 0 for Tecplot/preplot compatibility; measured zero values retain valid = 1. No data is extrapolated. mode_assignments.csv lists the source curve, assigned global mode, beta, and relative frequency matching cost for auditing. A blank matching cost marks a new mode.

For every matched surface, the command also writes a one-dimensional nfac_envelope_mode_*.dat or alpi_envelope_mode_*.dat curve. At each s, the envelope selects the largest valid value across beta and retains the beta and every corresponding quantity from that surface point. The envelope is computed separately for each physical mode; it never switches between matched mode surfaces. Locations without support are zero-filled with valid = 0.

Check the assignment report and plotted surfaces before interpreting mode identity near branch crossings.