Collisions of galaxies cause gas flows into the galaxy centers; these gas flows are thought to trigger rapid growth of supermassive black holes. This is seen in observational evidence that the examples of the most rapid black hole growth tend to be found in galaxy mergers. However, the physical mechanisms that transport the gas to galaxy centers remain uncertain. We have run a high resolution idealized galaxy merger simulation (broadly reproducing some observed properties of NGC 2623) to study the origin of torques that drive gas to the center, fueling both star formation and black hole growth. We find that both gravitational and hydrodynamic torques cause the reorganization of gas; the former generally dominates, but the latter can be important in the smaller scales with the nucleus. The paper has been submitted to a journal and a preprint is available.