  It is shown that the convective instability in electron fluids in 3D and 2D
Dirac semimetals is strongly inhibited. The major obstacles for the convection
are the effects of the Coulomb forces and the momentum relaxation related to
the interaction with impurities and phonons. The effect of the Coulomb forces
is less pronounced in 2D materials, such as graphene. However, momentum
relaxation still noticeably inhibits convection making it very difficult to
achieve in practice.
