BEGIN:VCALENDAR VERSION:2.0 PRODID:-//linuxsoftware.nz//NONSGML Joyous v1.4//EN BEGIN:VEVENT SUMMARY:Relativistic dissipative fluids DTSTART:20241004T143000Z DTEND:20241004T160000Z DTSTAMP:20260622T030332Z UID:302ffa4e-23cb-4026-bb35-7f916d798d7e SEQUENCE:1 CREATED:20241002T082230Z DESCRIPTION: In general relativity we don'\;t have any preferred time function\, so we can not have infinite propagation speeds. Thus\, paraboli c systems like the Navier-Stokes equations are not possible. To overcome t his several proposals for admissible theories have been put forward in the past. Notably\, the first ones were ill posed\, namely a small variation on the initial data produced huge differences on the solutions. Fortunatel y new proposals have arised which are well posed. Here we discuss one of t hem. In particular we shall concentrate on one describing conformally inva riant fluids\, the limit when the particle'\;s mass is much smaller th an their thermal speeds. In this case the universe of possible theories co llapses to a four parameter family\, Only one of them related to the propa gation speeds of the system. This case is well posed. We shall further dis cuss some simulations exploring these free parameter variations and some e fforts to construct algorithms to automatically generate computer codes fo r solving them. LAST-MODIFIED:20241002T082230Z LOCATION:Sala de Seminários do DF\, Pavilhão de Física\, 2º piso URL:http://df.vps.tecnico.ulisboa.pt/pt/eventos/relativistic-dissipative-f luids/ X-ALT-DESC;FMTTYPE=text/html:

In general relativ ity we don'\;t have any preferred time function\, so we can not have i nfinite propagation speeds. Thus\, parabolic systems like the Navier-Stoke s equations are not possible. To overcome this several proposals for admis sible theories have been put forward in the past.

Notably\, the first ones were ill posed\, namely a small variation on the initial data p roduced huge differences on the solutions. Fortunately new proposals have arised which are well posed. Here we discuss one of them. In particular we shall concentrate on one describing conformally invariant fluids\, the li mit when the particle'\;s mass is much smaller than their thermal spee ds.

In this case the universe of possible theories collapses to a four parameter family\, Only one of them related to the propagation spee ds of the system. This case is well posed. We shall further discuss some s imulations exploring these free parameter variations and some efforts to c onstruct algorithms to automatically generate computer codes for solving t hem.

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