  We study the kinematic and thermal vorticities in low-energy heavy-ion
collisions by using the Ultra-relativistic Quantum Molecular Dynamics (UrQMD)
model. We explore their time evolution and spatial distribution. We find that
the initial vorticities have a non-monotonic dependence on the collision energy
$\sqrt{s_{\rm NN}}$: as $\sqrt{s_{\rm NN}}$ grows the vorticities first
increase steeply and then decrease with the turning point around $\sqrt{s_{\rm
NN}}\sim 3-5$ GeV depending on the centrality.

Nuclear Theory;High Energy Physics - Phenomenology;Nuclear Experiment