Blocking and Frontogenesis by Two-Dimensional Terrain in Baroclinic Flow. Part II: Analysis of Flow Stagnation Mechanisms
نویسنده
چکیده
Numerical solutions presented in a companion paper show that two-dimensional mesoscale terrain becomes a much stronger barrier to a continuously stratified flow when the flow contains warm advection. Here it is shown that this baroclinic enhancement is a strictly nonlinear phenomenon. The linear analysis indicates a weakening of the upstream response in warm advection. However, a weakly nonlinear analysis shows that baroclinicity facilitates blocking in warm advection by strengthening the nonlinearity in the cross-mountain momentum equation in such a way as to amplify the vertical shear on the windward flank of the ridge. This is enough to send the flow past the blocking threshold even when conditions over the mountain are too linear to produce wave breaking. A more intuitive mechanism whereby the upstream static stability is increased by the nonlinearity in the temperature equation is found to be much less important.
منابع مشابه
Blocking and Frontogenesis by Two-Dimensional Terrain in Baroclinic Flow. Part I: Numerical Experiments
The shallow atmospheric fronts that develop in the early winter along the east coast of North America have been attributed, in various modeling and observational studies, to the land–sea contrasts in both surface heating and friction. However, typical synoptic conditions are such that these ‘‘coastal’’ fronts could also be a type of upstream influence by the Appalachian Mountain chain. Generali...
متن کاملMHD Three-Dimensional Stagnation-Point Flow and Heat Transfer of a Nanofluid over a Stretching Sheet
In this study, the three-dimensional magnetohydrodynamic (MHD) boundary layer of stagnation-point flow in a nanofluid was investigated. The Navier–Stokes equations were reduced to a set of nonlinear ordinary differential equations using a similarity transform. The similarity equations were solved for three types of nanoparticles: copper, alumina and titania with water as the base fluid, to inve...
متن کاملStagnation-point flow of a viscous fluid towards a stretching surface with variable thickness and thermal radiation
In the present analysis, we study the boundary layer flow of an incompressible viscous fluid near the two-dimensional stagnation-point flow over a stretching surface. The effects of variable thickness and radiation are also taken into account and assumed that the sheet is non-flat. Using suitable transformations, the governing partial differential equations are first converted to ordin...
متن کاملEffects of Brownian motion and Thermophoresis on MHD Mixed Convection Stagnation-point Flow of a Nanofluid Toward a Stretching Vertical Sheet in Porous Medium
This article deals with the study of the two-dimensional mixed convection magnetohydrodynamic (MHD) boundary layer of stagnation-point flow over a stretching vertical plate in porous medium filled with a nanofluid. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis in the presence of thermal radiation. The skin-friction coefficient, Nusselt number an...
متن کاملModeling and Analysis of Vehicles Flow on the Road
Abstract: This study is carried out to describe the behaviour of vehicles flow on the road, in the presence of blocking effects. A non-linear three dimensional system of ordinary differential equations is used to describe vehicles flow on the road. The study classify total vehicles population on the road into three compartments as Free – Slow – Released vehicles. The formulated model is well-po...
متن کامل