{
  "annotation_id": "55873cad-710d-44e6-b003-10203a948885",
  "date_created": "2026-03-02T18:01:03.482000Z",
  "date_modified": "2026-03-02T18:01:03.482000Z",
  "file_hash": "6ad1b656dfb8545ce1ac025d87db9cb7bdaeb9039c4d5396da38861e7d12d9c1",
  "private": false,
  "record": {
    "abstract": "We investigate the formation of acoustic horizons for an inviscid fluid\nmoving in a pipe in the case of stationary and axi-symmetric flow. We show\nthat, differently from what is generally believed, the acoustic horizon forms\nin correspondence of either a local minimum or maximum of the flux tube\ncross-section. Similarly, the external potential is required to have either a\nmaximum or a minimum at the horizon, so that the external force has to vanish\nthere. Choosing a power-law equation of state for the fluid, $P\\propto\n\\rho^{n}$, we solve the equations of the fluid dynamics and show that the two\npossibilities are realized respectively for $n\u003e-1$ and $n\u003c-1$. These results\nare extended also to the case of spherically symmetric flow.",
    "arxiv_id": "physics/0510164",
    "authors": [
      "M. Cadoni",
      "P. Pani"
    ],
    "categories": [
      "physics.flu-dyn",
      "gr-qc",
      "physics.class-ph"
    ],
    "doi": "10.1088/0264-9381/23/7/013",
    "journal_ref": "Class.Quant.Grav. 23 (2006) 2427-2434",
    "title": "Acoustic horizons for axially and spherically symmetric fluid flow",
    "url": "https://arxiv.org/abs/physics/0510164"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "a4e2fe28-7957-4bd1-a168-2d75c3070e65",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}