  Metasurfaces have shown unprecedented possibilities for wavefront
manipulation of waves. The research efforts have been focused on the
development of metasurfaces that perform a specific functionality for waves of
one physical nature, for example, for electromagnetic waves. In this work, we
propose the use of power-flow conformal metamirrors for creation of
multiphysics devices which can simultaneously control waves of different
nature. In particular, we introduce metasurface devices which perform specified
operations on both electromagnetic and acoustic waves at the same time. Using a
purely analytical model based on surface impedances, we introduce metasurfaces
that perform the same functionality for electromagnetic and acoustic waves and,
even more challenging, different functionalities for electromagnetics and
acoustics. We provide realistic topologies for practical implementations of
proposed metasurfaces and confirm the results with numerical simulations.
