The paper presents a computational technology of numerical simulation of turbulent flow over a hinged rotor on high-performance heterogeneous computer systems. A key part of the technology is the developed mathematical model describing the complex motions of triple-hinged rigid blades of a helicopter under the action of external and aerodynamic forces and its implementation using an original unstructured mesh-deformation algorithm. The mesh-deformation method exploits an auxiliary web-structured mesh with its elastic compression-expansion controlled by low-cost quasi-one-dimensional strand-based algorithms. The mechanics model is verified by solving the pendulum problems. To demonstrate the correctness of the developed techniques, the problems on taper stabilization and blade motion under cyclic control for model helicopter rotors are considered. All the presented computations are carried out using the code NOISEtte for solving aerodynamics and aeroacoustics problem. The code implements higher-accuracy methods of computational fluid dynamics on unstructured mixed-element meshes and operates with a high efficiency on modern supercomputers with arbitrary architectures including CPU cores and GPU accelerators.

Computational Fluid Dynamics demands substantial computational resources and advanced numerical algorithms for accurate simulation of fundamental and industrial problems. This paper presents an experience in assessing several numerical algorithms implemented recently into the in-house finite-volume code SINF/Flag-S developed at the Peter the Great St. Petersburg Polytechnic University for supercomputer simulation. Three topics are covered: (i) implementation and testing of an original geometric multigrid method for solving linear algebraic equations; (ii) application of a fractional step method for solving unsteady incompressible fluid motion equations; and (iii) description and testing of a density-based solver for compressible gas viscous flow simulation across a wide Mach number range. For each of the topics considered, the results of the calculations of some testing problems are presented, namely: a model problem of heat transfer in a cubic domain, turbulent Rayleigh–Bénard convection in a slightly tilted cylindrical container, free convective flow around a subsea cooler model, high-speed gas flow with strong effects of viscous-inviscid interaction. The parallel efficiency of the implemented algorithms is demonstrated, and their significance for large-scale simulations on supercomputers is highlighted.

The article examines potential applications of WAVEWATCH III (WW3), the thirdgeneration wind-wave model. This study delves into the implementation of hybrid parallelization (MPI-OpenMP) and the development of multiple-cell grids tailored for the Azov Sea region. It elucidates fundamental equations of the model, their discretization, and software execution. The multiple-cell grid strategy employs high-resolution cells within the region of interest, gradually increasing cell density in other areas to optimize memory consumption. A 6-level multiple-cell grid was specifically crafted for the Azov Sea, with an algorithm outlined for its generation incorporating two refinement methods. This algorithm enables the creation of refined multiple-cell grids near shorelines at varying levels, along with the capability to refine grid structures in arbitrary zones. Additionally, the article presents hybrid parallelization techniques for the wave spectral component (MPI-OpenMP), assessing scalability in both MPI and hybrid deployments. The WW3 model offers a multigrid option facilitating parallel operation of subdomains akin to domain decomposition, while ensuring parallelization of each subnet via the component decomposition method.

Excitation of a laminar gas micro-jet by acoustic impact and by pulse-periodic heat source was simulated using the FlowVision software package in 2D formulation at normal conditions. Heat source imitates an electrical discharge. Air jet was formed by channel with inner size of 0.7 mm with the Poiseuille velocity profile at inlet boundary, the maximum profile velocity was varied in a range of 2.5-10 m/s. Influence of heat source frequency and power on the large-scale vortex formation was described. In the case of a jet with a speed of 5 m/s, the natural oscillations of the jet in response to a single pulse had a frequency fres = 1380 Hz, so excitation of the jet was possible at close frequencies of 1190 Hz and 1500 Hz. At the same time, at a frequency of 1000 Hz (approximately equal to 2/3 fres), every second impulse acted in antiphase and the oscillations developed poorly. Dependence of flow structure from the jet velocity was obtained. The results obtained show the possibility of exciting a micro-jet using low-power electrical discharges such as spark, DBD or corona.

The paper covers a variant of architecture development of digital photonic computers. Along with quantum computers, they are one of the possible ways to overcome the crisis of computing performance. The data processing implementation in digital photonic computers at terahertz frequencies potentially provides the performance exceeding by two or more decimal orders of magnitude the performance of the most modern computing systems. The elements of digital photonic computer architecture described in the paper are focused on solving a wide class of computationally time-consuming problems in the paradigm of structural calculations. The problems of ensuring the performance and accuracy at solving problems on the developed digital photonic computer, as the processing rate should correspond to the data receipt rate, are considered. The synchronization and switching subsystem was designed and analyzed by the authors. At the synthesis (programming) stage, it forms a computational structure and provides both static and dynamic coordination of data flows in calculations.

The features of a statically typed functional-dataflow model of parallel computation and its mapping to the statically typed language of functional-dataflow parallel programming Smile are considered. To provide support for architecture-independent parallel programming, we used: a functional style, an implicit managing of calculations on data readiness, structured data objects that provide representation of various types of parallelism. A distinctive feature of the approach is the inclusion in the model of special asynchronous data objects that can generate events on partial filling. These data objects are stream and swarm. Each of these data objects has its own specifics to control by parallel calculations. A stream is used to process data of the same type that arrives sequentially and asynchronously at random intervals. A swarm is used to describe independent data of the same type or different types, on which it is possible to perform massive parallel operations. The use of streams and swarms in various situations as well as their mapping into each other and other program objects are shown. An analysis is made of the possibilities of transforming the formed language constructs into programming languages used in writing programs for modern parallel architectures.

Numerical modeling is one of the leading research tools for the climate problems. Among numerical models, researchers use, in particular, coupled models, that are numerical models describing more than one climate component dynamics and their interactions. The simulation results with such models depend on the way how these interactions are configured. Therefore, a proper configuration of the exchanges is crucial. The software called a "coupler" is often used to configure these interactions. The coupler is most helpful if the model components are independent of each other modules, their number exceeds two, and they have their own computational grid and time integration step. Key functions of the coupler are managing data exchange between models, setting up synchronous interaction between them based on the time integration step, and interpolating data from one model's computational grid to the other model's grid. Additional functions can also be implemented, e.g., fluxes computation between model components, data assimilation, working with the file system, etc. The coupler has one crucial feature: if there is a set of different models of climate system components, one can construct new coupled models by coupling various subsets of these components with coupler. This paper gives an overview of the SCM (SibCIOM Coupling Module) coupler we first developed for the model SibCIOM (Siberian Coupled Ice and Ocean Model). The description of this coupler has not been published before. The SCM coupler is a separate module to which the main climate system model component, such as atmospheric, oceanic, sea ice and land components, can be attached. Additional functions of this coupler include computation of atmosphere-to-ocean and atmosphere-to-ice fluxes and ocean and sea ice state correction using a tidal model. This paper also gives examples of two models constructed with the SCM coupler.