We present the results of large-eddy simulations (LES) of turbulent thermal convection
generated by surface cooling in a finite-depth stably stratified horizontal layer with
an isothermal bottom surface. The flow is a simplified model of turbulent convection
occurring in the warm shallow ocean during adverse weather events. Simulations are
performed in a 6 × 6 × 1 aspect ratio computational domain using the pseudo-spectral
Fourier method in the horizontal plane and finite-difference discretization on a high-resolution
clustered grid in the vertical direction. A moderate value of the Reynolds
number and two different values of the Richardson number corresponding to a weak
initial stratification are considered. A version of the dynamic model is applied as
a subgrid-scale (SGS) closure. Its performance is evaluated based on comparison
with the results of direct numerical simulations (DNS) and simulations using the
Smagorinsky model. Comprehensive study of the spatial structure and statistical
properties of the developed turbulent state shows some similarity to Rayleigh–Bénard
convection and other types of turbulent thermal convection in horizontal layers, but
also reveals distinctive features such as the dominance of a large-scale pattern of
descending plumes and strong turbulent fluctuations near the surface.
Reservoir computing model of two-dimensional turbulent convection