The high-frequency quasi-periodic oscillations (HF QPOs) in neutron star and stellar-mass black hole X-ray binaries may be the result of a resonance between the radial and vertical epicyclic oscillations in strong gravity. In this paper we investigate the resonant coupling between the epicyclic modes in a torus in a strong gravitational field. We perform numerical simulations of axisymmetric constant angular momentum tori in the pseudo-Newtonian potential.