Can supernova shells feed supermassive black holes in galactic nuclei?

Aims. We simulate shells created by supernovae expanding into the interstellar medium of the nuclear region of a galaxy, and analyze how the shell evolution is influenced by the supernova position relative to the galactic center, by the interstellar matter density, and by the combined gravitational pull of the nuclear star cluster and supermassive black hole (SMBH). Methods. We adopted simplified hydrodynamical simulations using the infinitesimally thin layer approximation in 3D (code RING) and determined whether and where the shell expansion may bring new gas into the inner parsec around the SMBH. Results. The simulations show that supernovae occurring within a conical region around the rotational axis of the galaxy can feed the central accretion disk surrounding the SMBH. For ambient densities between 103 and 105 cm−3, the average mass deposited into the central parsec by individual supernovae varies between 10 and 1000 solar masses depending on the ambient density and the spatial distribution of supernova events. Supernovae occurring in the aftermath of a starburst event near a galactic center can supply two to three orders of magnitude more mass into the central parsec, depending on the magnitude of the starburst. The deposited mass typically encounters and joins an accretion disk. The fate of that mass is then divided between the growth of the SMBH and an energetically driven outflow from the disk.

An adjustable law of motion for relativistic spherical shells

A classical and a relativistic law of motion for an advancing shell are deduced applying the thin layer approximation. A new parameter connected with the quantity of absorbed matter in the expansion is introduced; this allows the matching of theory with observation.

Simulating the Heating Cycle of a Thin Film Photovoltaic Cell During Rapid Thermal Processing

In this paper a detailed description of a modeling method for the heating cycle of a thin film Photovoltaic (PV) cell during Rapid Thermal Processing (RTP) is presented. The paper explores the challenges of numerically simulating the heating of the PV during RTP and proposes a comprehensive solution for solving these problems. In the proposed method, the thermal model is based on the Component Interaction Network (CIN) approach, while radiation is calculated by a zonal method based on the flux planes approximation and the Thin Layer Approximation (TLA) adapted for semitransparent sheets with small thickness. Various simulations using the model are performed and compared with experimental results. The comparisons demonstrate the efficiency of the modeling approach developed for PV cells in RTP chambers.

Transient Radiation and Conduction Heat Transfer in Glass Sheets by the Thin Layer Approximation

This paper is devoted to the simulation of 3D transient radiation and conduction heat transfer occurring inside thin glass sheets undergoing high temperature processing. The glass is considered as an absorbing, emitting, and nonscattering medium. The zonal method is used to establish the governing radiation transfer model. Direct exchange areas are calculated by the flux planes approximation. The thin layer approximation (TLA) is then introduced for increasing CPU efficiency. Three different numerical integration schemes made possible by the TLA are presented. Comparisons are made, with calculations performed using the finite volume method (FVM). The transient coupled energy equation is solved by a full implicit control volume method using the incomplete Cholesky conjugate gradient method. The heat transfer analysis of a glass sheet residing inside a hot rectangular enclosure is studied. Results obtained by the zonal method, with or without the TLA, are in close agreement with those obtained by the FVM. CPU requirements for radiative heat transfer analysis of the zonal method with TLA are, depending on the numerical integration scheme used, between 8 and 23 times smaller than those of the zonal method without TLA. The difference between the results of the different models never exceeds 4%. The zonal method with the TLA offered significant improvements in CPU time when compared with the original zonal method with similar or acceptable accuracy.