The turbulent energy equation, together with a modified mixing length, is adopted to close the governing equations in the turbulent planetary boundary layer under stratification conditions. The system of governing equations is decoupled by introducing a stratification parameter, Q. Numerical integration of the system, in general, is outlined and should be easily implemented. Results for the mom...

The effect of thermal stratification on the ignition of a lean homogeneous n-heptane/air mixture at constant volume and high pressure is investigated by direct numerical simulations (DNS) with a new 58species reduced kinetic mechanism developed for very lean mixtures from the detailed LLNL mechanism (H.J. Curran et al., Combust. Flame 129 (2002) 253–280). Two-dimensional DNS are performed in a ...

Some HVAC systems save energy by creating stratified air temperature distributions in which the occupied lower regions are cooler and the upper regions warmer. Comfort standards prescribe a 3°C limit to vertical stratification, independent of where the mean temperature is relative to the comfort zone. This paper evaluates thermal comfort in stratified environments using a model developed to pre...

Large-eddy simulation (LES) equipped with the one-equation subgrid-scale (SGS) model is employed to investigate the mean flows and turbulence over idealized two-dimensional (2D) street canyons in various unstable thermal stratifications. The building-height-tostreet-width (aspect) ratio is equalto unity so the flows inside a street canyon are in the skimming flow regime. Periodic boundaries are...

Detailed simulation of the thermal stresses of the reactor pressure vessel (RPV) wall in case of pressurized thermal shock (PTS) requires the simulation of the thermal mixing of cold high-pressure safety injection (HPI) water injected to the cold leg and flowing further to the downcomer. The simulation of the complex mixing phenomena including e.g. stratification in the cold leg and buoyancy dr...