The paper addresses Rayleigh–Taylor instability
(RTI) problems and presents a method of describing an interface
with markers on a Eulerian mesh, which is implemented in
the MAH-3 code. The proposed method allows a more accurate
description of the evolution of the interface caused by
Rayleigh–Taylor perturbations and preserves symmetry
of the interface under appropriate symmetry of the problem
(planar, cylindrical, and spherical). The method employs an
unstructured triangular mesh of makers. Method capabilities
are demonstrated on 2D and 3D Rayleigh–Taylor instability
problems.