write_zeta_vtk

Given a list of arrays representing the coordinates of a set of n_surf UVLM lattices and organised as:

zeta[n_surf][3,M+1,N=1]

this function writes a vtk for each of the n_surf surfaces.

Input:

• zeta: lattice coordinates to plot
• zeta_ref: reference lattice used to compute the magnitude of displacements
• filename_root: initial part of filename (full path) without file

extension (.vtk)