  It is shown that the convective instability in electron fluids in three- and
two-dimensional (3D and 2D) Dirac and Weyl semimetals is strongly inhibited.
The major obstacles for electron 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.
