  Dynamics of cylindrical and spherical relativistic domain walls is
investigated with the help of a new method based on Taylor expansion of the
scalar field in a vicinity of the core of the wall. Internal oscillatory modes
for the domain walls are found. These modes are non-analytic in the "width" of
the domain wall. Rather non-trivial transformation to a special coordinate
system, widely used in investigations of relativistic domain walls, is studied
in detail.
