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

TL;DR

This paper presents large-scale GPU-accelerated simulations of high-Rayleigh-number thermal convection and introduces an in-situ visualization workflow to analyze boundary layer dynamics and turbulent fluctuations.

Contribution

It demonstrates the feasibility of high-resolution simulations at Ra=10^{12} using GPUs and develops an in-situ workflow for real-time visualization of boundary layer fluctuations.

Findings

Simulated Rayleigh-Bénard convection up to Ra=10^{12} on supercomputers.

Implemented an in-situ visualization workflow for high-frequency turbulence data.

Achieved detailed analysis of boundary layer dynamics in turbulent convection.

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.