We propose to extend the d'Humi\'eres version of the lattice Boltzmann scheme
to triangular meshes. We use Bravais lattices or more general lattices with the
property that the degree of each internal vertex is supposed to be constant. On
such meshes, it is possible to define the lattice Boltzmann scheme as a
discrete particle method, without need of finite volume formulation or
Delaunay-Voronoi hypothesis for the lattice. We test this idea for the heat
equation and perform an asymptotic analysis with the Taylor expansion method
for two schemes named D2T4 and D2T7. The results show a convergence up to
second order accuracy and set new questions concerning a possible
super-convergence.Comment: 23 page