Parallel ray tracing algorithm for radiation field analysis and pinhole imaging of radiative gas An original algorithm was developed for ray tracing across unstructured 3D grid, and grid-characteristic computation of radiative energy transfer using MPI parallel technique and grid decomposition. The developed algorithm provides accounting the anisotropy of the radiation field in complex multiscale 3D magneto hydrodynamic simulations. The algorithm is implemented as a C++ code. Accurate rational calculations are applied for the intersection of rays with grid elements. Tracing of different rays within a single MPI-process is carried out in parallel with the use of OpenMP threads. Acceleration and scalability of the implemented algorithms were investigated including a comparison with other solvers within MHD code. Proposed applications are considered.

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The research code MARPLE was originally created to model high-speed dynamic processes caused by the action of high-intensity energy fluxes on matter. At present, it is a universal tool able to solve various continuum mechanics problems. The implemented physical models are the following: single-fluid two-temperature MHD model of plasma dynamics, including electron-ion energy exchange and generalized Ohm's law; model of electrical and thermal conductivity taking into account the anisotropy in the magnetic field; radiative heat transfer: models pertinent to optically thin as well as optically thick media: techniques for taking into account radiative cooling losses, spectral multigroup diffusion transfer, laser radiation propagation etc.; model of multicomponent flow. Calculations are performed using wide-range equations of state, transport and optical data. The MARPLE code utilises modern computational technologies based on block structured and unstructured meshes consisting of tetrahedral, hexahedral, prismatic elements and their combinations. The solvers implement conservation laws using high-resolution techniques. We apply the physical splitting to solve the governing system. The object-oriented approach to software design is used, as well as methods of object and generic programming (C++ implementation language). Design of computational domains is provided by means of integrated SALOME open source CAD-CAE system. Marple works as MPI application for modern HPC systems. The paper presents examples of problems in plasma dynamics, magnetohydrodynamics, astrophysics, and solid thermomechanics solved by means of the MARPLE code.