The computation of turbulent natural convection flows - Turbulence ...

Chapter 1
Introduction
In this research, various RANS turbulence modelling strategies are em-
ployed to predict buoyant flows in enclosed cavities with different angles of
inclination and an annular horizontal penetration with an open-end. Some of
the specific aspects of turbulence modelling examined are appropriate levels
of modelling to employ for the turbulent stresses and turbulent heat fluxes in
the fully turbulent region, and the modelling of near-wall turbulence across
the viscosity-affected layer.
1.1 Buoyant flows
Most flows that take place in our surroundings are induced, or affected,
by buoyancy. Buoyant flows can be seen as air circulation around our bod-
ies, in the atmosphere, oceanic circulation, etc. Buoyant flows originate from
density differences, often resulting from temperature gradients. The buoy-
ant flows can be subdivided into two major broad categories. One is that of
buoyant flows induced by temperature differences or heat transfer between a
fluid and a surface immersed in it, which are called external buoyancy induced
flows. The other category is that of buoyant flows that occur inside enclosures
bounded by surfaces which are at different temperatures, referred to as inter-
nal buoyancy-driven flows.
In the past years, there has been intensive research on buoyant flows. These
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