[en] Non-ideal fluid motions are studied. Spherical self-similar convergence is calculated for a strong shock in an ideal medium. Group theory is used to place a symmetry condition on the adiabatic bulk modulus, B/sub s/(p,v), for which three independent scale transformations of Euler's equations are admitted. The types of non-ideal media which satisfy the bulk modulus symmetry condition include equations of state of Mie-Grusneisen type. Thus the theory applies to a wide class of materials. In particular it applies to non-degenerate solids at shock pressures well above the yield stress