Large-eddy simulation of natural convection in an asymmetrically-heated vertical parallel-plate channel: Assessment of subgrid-scale models

The performance of four different large-eddy simulation subgrid-scale models has been examined a posteriori for natural convection in an asymmetrically-heated vertical parallel-plate channel with a high aspect ratio. The compressible three-dimensional Favre-filtered mass, momentum and energy conservation equations have been closed using the Smagorinsky, dynamic, approximate localised dynamic and Vreman models. A two-stage predictor–corrector numerical methodology for low-Mach-number compressible flows was adopted to strongly couple the density with the Navier–Stokes equations. Based on the comparison with experimental data, it has been shown that the Smagorinsky model predicts inaccurate near-wall flow dynamics and delayed transitional behaviour while both dynamic procedures to compute the Smagorinsky model coefficient result in over prediction of wall temperatures, suggesting an under estimation of subgrid-scale dissipation. The time extrapolation procedure utilised in the approximate localised dynamic model has been shown to produce better adaptation towards the local flow behaviour when compared with the standard dynamic model. At the same time, time-averaged wall temperature and velocity field profiles have been well captured by the Vreman model, demonstrating its superiority when compared to the rest of the models.

► Natural convection in vertical channels has been numerically simulated.
► Various SGS models have been tested for buoyancy-driven flows.
► Vreman model has well captured the mean and fluctuating fields.