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SUMMARY:Grid-based operator-splitting solvers for radiative transfer with 
 sharply peaked sources
DTSTART;VALUE=DATE-TIME:20261030T145000Z
DTEND;VALUE=DATE-TIME:20261030T150500Z
DTSTAMP;VALUE=DATE-TIME:20261030T190935Z
UID:indico-contribution-6342@cern.ch
DESCRIPTION:Speakers: Grigory Vorobyev (Lomonosov MSU)\nDeterministic solu
 tion of the radiative transfer equation (RTE) on a fixed grid is a possibl
 e alternative to Monte Carlo photon tracking for light propagation in wate
 r and ice\, for example in neutrino telescopes like BaikalGVD. However\, t
 he relevant sources\, Cherenkov light from charged-particle tracks\, are s
 harply localized in both space and direction. We present an implementation
  of a second-order Strang-split RTE solver in 3D space + 2D direction. It 
 uses a spherical t-design angular grid ($10^2 - 10^4$ directions)\, a coll
 ision step that is exact in spherical-harmonic space for a Henyey-Greenste
 in phase function\, and a semi-Lagrangian cubic-spline streaming step that
  conserves energy to $10^{-7} - 10^{-15}$. We study three obstacles to pra
 ctical use: Ray effect\, sharp sources (Gibbs oscillations)\, memory\\spee
 d cost. We discuss mitigation through uncollided-flux splitting and hybrid
  Monte Carlo–grid schemes. The work is ongoing.\n\nhttps://indico.partic
 le.mephi.ru/event/626/contributions/6342/
LOCATION: Conference Hall 2
URL:https://indico.particle.mephi.ru/event/626/contributions/6342/
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