Abstract
Parametric decay instability (PDI) generated in milliseconds is an important physical phenomenon in ionospheric heating. Usually, numerical simulations are used to study PDI mechanisms. They can intuitively investigate the generation and development process of PDI, which is necessary in experimental studies. When simulating the PDI phenomenon through the explicit finite-difference time-domain (FDTD), the spatial scale spans from kilometers to centimeters, and the time scale needs to meet the Courant–Friedrichs–Lewy condition. Simulating the PDI phenomenon is time-consuming and difficult due to the high spatial resolution and strict restriction on the discrete time step. Although a nested mesh technique can boost the computational efficiency, the application of a parallel strategy is imperative to further improve it. In this study, we present a hybrid Message Passing Interface (MPI)/OpenMP parallelization scheme to solve the above-mentioned problems. This scheme can achieve an adaptive calculation and automatic allocation of MPI tasks and OpenMP threads, proving its flexibility and portability. Under the EISCAT background parameters, the PDI phenomenon was simulated. The results of the wave mode conversion and intense localized turbulence were identical to those of the serial program. Furthermore, a new simulation example and the effect of the cavity depth on electrostatic waves and negative ion density cavity were investigated. By utilizing the proposed parallelization scheme, the simulation time can be reduced from 70 h for the serial program to 3.6 h.
Highlights
We present a hybrid Message Passing Interface (MPI) and OpenMP parallelization scheme based on the nested mesh finite-difference time-domain (FDTD) for parametric decay instability (PDI) studies
We presented a hybrid MPI and OpenMP parallelization scheme based on the nested mesh FDTD to study the PDI
By examining the controlling equations of the PDI, the physical parameters were discretized, and a numerical simulation method based on the nested grid FDTD was established
Summary
Ionosphere heating experiments using ground-based high-power and high-frequency (HF) transmitters can cause ionospheric perturbations, leading to linear and nonlinear interactions between ionospheric plasma and waves [1–3]. The Yee structure of the FDTD method can separately define the physical properties of each grid-based structure and describe the number density, geomagnetic field, and other profile characteristics of different positions in the ionosphere [12]. Electric and magnetic fields in the classic Yee structure only have temporal and spatial discretization, which is not sufficient to simulate PDI [13] This structure does not have temporal and spatial discretization schemes for the ionospheric plasma number density and velocity. The FDTD method was developed to simulate PDI by expanding the discretization scheme of the physical characteristic parameters during interactions between ionospheric plasma and EM waves. We present a hybrid MPI and OpenMP parallelization scheme based on the nested mesh FDTD for PDI studies. The dependence of the cavity depth on the electrostatic wave energy captured by the cavity is obtained
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