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43. Deryugin Yu.N., Sarazov A.V., Zhuchkov R.N. Specific design features of the computing method on the Chimera-
type grids for non-structured grids// Mathematical simulation. 2017. Vol. 29, � 2. pp. 106-118.
Using Didal distributed data library for implementation of parallel fragmented programs for distributed
memory supercomputers
G. A. Schukin
Institute of Computational Mathematics and Mathematical Geophysics SB RAS
Novosibirsk State Technical University
Email: schukin@ssd.sscc.ru
DOI 10.24412/cl-35065-2021-1-01-82
Distributed data library Didal [1] is designed to facilitate development of efficient parallel programs for
distributed memory supercomputers. The aim of the library is to provide high-level distributed data structures
coupled with different strategies for data partitioning, distribution and load balancing, to develop parallel pro-
grams with. The library approach allows to use all existing tools for parallel program development, debugging
and profiling, as well as optimized C/C++ codes. One of defining features of Didal is its support of fragmented
programming [2]. In fragmented programming a parallel program is represented as sets of data and computa-
tional pieces (fragments), number and sizes of fragments being static or dynamic parameters. Results of im-
plementation of several parallel programs with Didal library and fragmented programming approach are pre-
sented. Details of parallel fragmented programs implementations, as well as key aspects of Didal's design, are
provided. The programs' performance is measured and compared with other parallel programming models.
References
1. Schukin G.A. Didal: distributed data management library for distributed memory supercomputers // Proceedings
of 13th international conference �Parallel Computational Technologies 2019 (PaVT 2019)�. 2019. P. 466.
2. Malyshkin V.E., Perepelkin V.A., Schukin G.A. Scalable distributed data allocation in LuNA fragmented
programming system // The J. of Supercomputing. 2017. V. 73, N. 2. P. 726-732.
3. Ivanov A. A. The title of the book. M.: Nauka, 1978.
Multi-grid starting initialization as a way to achieve higher convergence rates in industry-specific hypersonic
aerodynamic simulations
A. V. Struchkov, A. S. Kozelkov, D. K. Zelenskiy
FSUE �Russian Federal Nuclear Center � All-Russian Research Institute of Experimental Physics�, Sarov, Nizhny
Novgorod Region
Email: AnVStruchkov@vniief.ru
DOI 10.24412/cl-35065-2021-1-01-84
The paper presents a multilevel geometric initialization-based algorithm [1�2] to speed up external aero-
dynamics simulations. This method provides higher convergence rates and stability of numerical results in the
flow structure formation and settling phase. The concept of the method is to generate a series of coarse grids
[3] based on a parent grid to find solutions on each of the grids and to subsequently interpolate them to a fin-
er grid. The solution calculated on the finest of the grids constructed in series is then interpolated to the par-
ent grid, thus representing the starting initialization on it. The algorithm can be used on unstructured grids
with an arbitrary cell shape. As a cell combination criterion to form new control volumes in the successive grid
coarsening, the algorithm uses a relationship calculated from face areas and cell volumes. The cell combina-
tion process is based on the analysis of the weighted graph. Solution stability and convergence analysis was
performed by test simulations of a supersonic flow in a channel with a wedge [4] and a hypersonic flow over a
cone [5]. As a result, the geometric multi-level initialization algorithm shortened the runtime by 23 percent.
References
1. Volkov K.N., Deryugin Yu.N., Emelyanov V.N., Karpenko A.G., Kozelkov A.S., Teterina I.V. Methods to accelerate gas
dynamics computations on unstructured meshes. M.: Fizmatlit, 2013, 536 p. [In Russian].
2. Francescatto J., Dervieux A. A semi-coarsening strategy for unstructured multigrid based on agglomeration //
International J. for Numerical Methods in Fluids. 1998. V. 26. No. 8. P. 927-957.
3. Lassaline J.V., Zingg D.W. An investigation of directional-coarsening and line-implicit smoothing applied to
agglomeration multigrid // AIAA Paper. 2003. No. 2003-3435.
4. Povkh I.L. Hydraulics. 2nd edition, revised and corrected L. // Mashinostroenie, 1976 � 504 p. [In Russian].
5. Krasnov N.F. Aerodynamics of solids of revolution // Publisher: Mashinostroenie. Year: 1964. Pages: 573. [In
Russian].
Implementation of the imitation method of the propeller rotation to simulate marine propellers
D. A. Utkin, A. S. Kozelkov, V. V. Kurulin, K. S. Plygunova
FSUE �Russian Federal Nuclear Center � All-Russian Research Institute of Experimental Physics�, Sarov, Nizhny
Novgorod Region
Email: DAUtkin@vniief.ru
DOI 10.24412/cl-35065-2021-1-01-85
Model implementation of a virtual propeller for the numerical simulation of the ship-related dynamic
problems on the water surface is described in LOGOS software package [1]. The model is based on the imita-
tion of the marine propellers operation of a ship with the help of a given source of bulk forces, which is set in
the area of the 3D location of the propeller [2, 3]. As rotating solid blades are actually absent in the rated op-
erating conditions, the screw stop, the moment and the efficiency of the propeller as a preliminary specified
function of the pitch ratio are introduced to account for the geometric rotating properties of the immediate
propeller. The realized approach has been tested and implemented to solve industrial problems of ship cruis-
ing using moving grids.
References
1. Kozelkov A.S., Kurulin V.V., Lashkin S.V., Shagaliev R.M., Yalozo A.V., Investigation of supercomputer capabilities
for the scalable numerical simulation of computational fluid dynamics problems in industrial applications //
Computational mathematics and mathematical physics, 2016, V. 56, Iss. 8. P. 1524�1535.
2. Stern, F., Kim, H.T., Patel, C., Chen, H.C., A viscous flow approach to the computation of propeller hull interaction
// J. of Ship Research, vol. 32, no. 4, 1988b.
3. Hough, G. and Ordway, D., The generalized actuator disk // Developments in Theoretical and Applied Mechanics.
1965. 2:317-336.
Verification of the LOGOS software package for multi-material flow simulations
K. B. Volodchenkova, R. R. Giniyatullin
FSUE �Russian Federal Nuclear Center � All-Russian Research Institute of Experimental Physics�, Sarov, Nizhny
Novgorod Region
Email: Ksuwatomsk@mail.ru
DOI 10.24412/cl-35065-2021-1-01-86
In this paper, we consider convective flow approximations, which are used to simulate incompressible
low-velocity multi-material flows on unstructured grids. The simulation technique is based on the SIMPLE algo-
rithm [1], which serves for numerical simulations of incompressible and low-compressible flows. Using the
