Eventos Anais de eventos
ENCIT 2018
Brazilian Congress of Thermal Sciences and Engineering
Direct numerical simulation of vacillation in centrifugal convection
Submission Author:
Diogo B. Pitz , PR , United Kingdom
Co-Authors:
Diogo B. Pitz, Olaf Marxen, John Chew
Presenter: Diogo B. Pitz
doi://10.26678/ABCM.ENCIT2018.CIT18-0500
Abstract
In rotating systems characterised by a constant angular velocity, i.e. without differential rotation, buoyancy effects occur if a temperature gradient is imposed. In particular, if the centrifugal acceleration induced by rotation is large enough, buoyancy effects in the radial direction compete with those induced by gravity, and in many cases the centrifugal force alone dominates the buoyant flow dynamics. In this study flow in a rotating, differentially heated cylindrical annulus is studied by means of direct numerical simulation (DNS), where the temperature at the outer cylinder is higher than that at the inner cylinder, and the flow is induced by buoyancy effects arising from the centrifugal force. This configuration is relevant in industrial applications, such as compressor cavities of turbomachinery internal air systems, and also in flows of geophysical interest. From previous work it is known that convection first starts in the form of nearly-circular counter-rotating rolls which span the entire axial length of the cavity, and also that at low Rayleigh numbers Ra the flow is dominated by a single azimuthal mode, whereas at high Ra broadband effects dominate. In this study the Rayleigh number is increased progressively and we investigate mode interactions that occur during the vacillation regime, which eventually lead the flow to a turbulent state.
Keywords
centrifugal convection, rotating cavities, transition to turbulence, direct numerical simulation, High-order methods
