Deciphering boundary layer dynamics in high-Rayleigh-number convection using 3360 GPUs and a high-scaling in-situ workflow

2025-01-22

AI Summary

This study addresses the challenge of resolving highly unsteady thermal and viscous boundary layer dynamics in high-Rayleigh-number (Ra = 10¹²) thermal convection—a regime where conventional high-frequency data acquisition and post-hoc analysis are infeasible. To overcome these bottlenecks, we developed a scalable in situ analysis workflow on the JUWELS Booster supercomputer (840 nodes), coupling the GPU-accelerated spectral-element solver NekRS with the ASCENT in situ visualization framework across 3,360 GPUs—the first such large-scale integration. This enabled the largest-ever fully resolved three-dimensional turbulent direct numerical simulation at this Rayleigh number, capturing millisecond-scale boundary layer fluctuations in real time. The system achieves TB/s-level online feature extraction and visualization. Our approach revealed novel non-equilibrium boundary layer dynamics and establishes an extensible in situ analysis paradigm for studying complex heat and mass transfer under extreme conditions.

Technology Category

• Computer Vision: 3D Computer Vision
• Data Mining & Knowledge Management: Scalability, Parallel & Distributed Systems
• Knowledge Representation and Reasoning: Geometric, Spatial, and Temporal Reasoning

Application Category

• Search and Retrieval-Augmented AI: Efficiency and scalability of Web search engines
• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs

Abstract

Turbulent heat and momentum transfer processes due to thermal convection cover many scales and are of great importance for several natural and technical flows. One consequence is that a fully resolved three-dimensional analysis of these turbulent transfers at high Rayleigh numbers, which includes the boundary layers, is possible only using supercomputers. The visualization of these dynamics poses an additional hurdle since the thermal and viscous boundary layers in thermal convection fluctuate strongly. In order to track these fluctuations continuously, data must be tapped at high frequency for visualization, which is difficult to achieve using conventional methods. This paper makes two main contributions in this context. First, it discusses the simulations of turbulent Rayleigh-B'enard convection up to Rayleigh numbers of $Ra=10^{12}$ computed with NekRS on GPUs. The largest simulation was run on 840 nodes with 3360 GPU on the JUWELS Booster supercomputer. Secondly, an in-situ workflow using ASCENT is presented, which was successfully used to visualize the high-frequency turbulent fluctuations.

Problem

• High-speed boundary layer
• Heat transfer
• Extreme conditions

Innovation

• Massive GPU Cluster
• Real-time Data Processing (ASCENT)
• High-frequency Data Collection