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Title: Interacting thermals
Author: Hart, Alison Claire
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2008
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This thesis addresses the question of how thermals evolve and interact when released in proximity to one another. The research reported focuses on the simultaneous release of an isolated group of thermals in a larger domain, rather than an array of thermals spanning a whole horizontal plane. With multiple thermals, the fluid available between the thermals is limited and this might be expected to lead to competition between the thermals for the surrounding fluid. The evolution of the thermals and the interaction between them will depend on their initial separation. If released close enough to each other there will be mixing between them and, in some cases, merging, whereas if the separation is large compared with the depth of the domain they may be expected to develop as if in isolation. Initially, the results for a thermal released in isolation are studied and the sensitivity to changes in initial buoyancy and the arrangement of fluid are examined. Having determined the experimental constants for an isolated thermal with certain initial conditions, the change in behaviour from the isolated self-similar case due to the presence of a second thermal is considered. A surprising lack of interaction between the thermals before the point at which the thermals first come into contact is discovered and a possible model for two thermals released in proximity to each other is suggested. In order to better understand the merging of the thermals the flow is considered from different angles of view. The distribution of mass within each two-dimensional projection is examined and compared to that of an idealised spherical thermal with uniform density as well as other possible models for a thermal.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available