We consider several modi cations of the Euler system of uid dynamics including its pressureless
variant driven by non-local interaction repulsive-attractive and alignment forces in the space dimension
N
=
2
;
3. These models arise in the study of self-organisation in collective behavior modeling of animals and
crowds. We adapt the method of convex integration to show the existence of in nitely many global-in-time
weak solutions for any bounded initial data. Then we consider the class of
dissipative
solutions satisfying, in
addition, the associated global energy balance (inequality). We identify a large set of initial data for which
the problem admits in nitely many dissipative weak solutions. Finally, we establish a weak-strong uniqueness
principle for the pressure driven Euler system with non-local interaction terms as well as for the pressureless
system with Newtonian interaction.