Numerical Convergence in Solar Convection in Implicit Large Eddy Simulations

by Gustavo Guerrero (Universidade Federal de Minas Gerais, Belo Horizonte, Brazil)

Tuesday 15 Feb 2022, 15:00 → 16:00 Europe/Stockholm

http://stockholmuniversity.zoom.us/j/940229961

Simulating turbulent flows at high Reynolds numbers (Re) is a formidable challenge, especially when there are few observational constraints like in the case of deep solar convection. An appealing idea is performing simulations whose solutions become independent of the non-physical influence of numerical resolution. In this talk I'll present our attempts to achieve such solutions with the use of implicit large-eddy simulations (ILES). I'll present the analysis of numerical convergence of ILES of turbulent convection in 2D, with resolutions between 64^2 and 2048^2 grid points, along with the estimation of their effective viscosities, resulting in effective Reynolds numbers between ~1 and ∼10^4 . The thermodynamic structure of our model resembles the solar interior, including a fraction of the radiative zone and the convection zone. In the convective layer, the ILES solutions converge for the simulations with ≥ 512^2 grid points, as evidenced by the integral properties of the flow and its power spectra. Most importantly, we found that even a resolution of 128^2 grid points, Re ∼ 10, is sufficient to capture the dynamics of the large scales accurately. This is a consequence of the ILES method allowing that the energy contained in these scales is the same in simulations with low and high resolution. In the stable layer we found the excitation of internal gravity waves, and the development of QBO-like oscillatory horizontal motions, yet high resolution is needed to capture their development and interaction. Recent results extending our analysis to 3D global simulations will be also presented.
http://arxiv.org/abs/2202.02767

Guerrero_2022-Feb-15.mp4