In the field of computational fluid dynamics, Smoothed Particle Hydrodynamics (SPH) serves as a powerful tool for investigating complex fluid interactions and instabilities. For the practical SPH simulation of large-scale fluid phenomena such as tsunamis, volcanic eruptions, and planetary collisions, it typically requires billions of particles, as the numerical resolution increases proportionally with the number of particles. To efficiently conduct large-scale SPH simulations on modern supercomputers with massive many-core processors, we propose a novel SPH implementation leveraging multi-level parallelism and a corresponding three-level load balancing strategy. Our load balancing approach comprises: (1) a process-level domain decomposition algorithm based on an improved 1D partitioning exact algorithm; (2) an adaptive recursive cell subdivision method; (3) a fine-grained dynamic thread-level task scheduling strategy. Our experiment uses 1 billion particles to simulate converging Richtmyer–Meshkov instability and verifies the effect of load balancing on new Sunway supercomputer. As the shockwave converges on the central interface area, our load balancing strategy breaks the bottleneck constraints on the slowest node, increases the balance of computational loads between nodes from 30.01% to 91.48%, and achieves a 2.8 × improvement in computational performance. Finally, our implementation enables each CPU to handle 10 million particles and scale from 1 CPU to 100,000 CPUs (in total 39 million cores with 1 trillion particles) with a performance of 80.4% parallel efficiency.

People are increasingly concerned about how tectonic processes affect climate and vice versa. We establish a cross-sphere modeling system for volcanic eruptions and atmosphere circulation on a new Sunway supercomputer with a spatial resolution from 10m locally to 3km globally, using an improved multimedium and multiphase smoothed particle hydrodynamics (SPH) combined with a fully coupled meteorology-chemistry global atmospheric modeling scheme. We achieve 400 billion particles and 80% parallel efficiency using 39,000,000 processor cores. The simulation captures the whole dynamic process of the Tonga eruption from shock waves, earthquakes, tsunamis, mushroom clouds to the following 6--7 days of transport and diffusion of ash and water vapor, and preliminarily obtains the influence effect of full coupling of volcano, earthquake, ocean and atmosphere. This work is of great significance for deeply understanding the interaction between tectonic processes and climate change, and establishing an early warning simulation system for similar global hazard events.