Numerical simulation of bore generation and morphology in thermal and Doppler ducts

Abstract. We perform a series of numerical simulations employing a model describing nonlinear incompressible dynamics to explore bore generation and morphology for several ducting geometries. These include idealized thermal ducts in close proximity to, and more remote from, reflecting boundaries, an idealized Doppler duct remote from boundaries, and a combination of thermal and Doppler ducts at nearby altitudes. Based on observed bore environments, we assume initial long-wave perturbations having sinusoidal form and large amplitudes. Results indicate that close proximity of a duct to reflecting boundaries enhances bore development, that both thermal and Doppler ducts support bore development for long-wave perturbations of sufficiently large amplitudes, and that bore structures and evolutions exhibit both features anticipated by idealized bore theory and departures that remain to be explored in detail.