Witte, Michael James

"Thermal-burst modeling of a double-diffusive ""diffusive"" interface"

Witte, Michael James

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Title: "Thermal-burst modeling of a double-diffusive ""diffusive"" interface"
Author(s): Witte, Michael James
Issue Date: 1989
Doctoral Committee Chair(s): Newell, Ty A.
Department of Study: Mechanical Science and Engineering
Discipline: Mechanical Engineering
Degree Granting Institution: University of Illinois at Urbana-Champaign
Degree Name: Ph.D.
Degree Level: Dissertation
Keyword(s): Engineering, Mechanical
Language: eng
Abstract: "The operation of a double-diffusive ""diffusive"" interface may be characterized by three regimes: quasi-steady entraining (often called the variable regime), quasi-steady non-entraining (often called the constant regime), and transient. Using a thermal burst modeling approach, new models have been developed for the quasi-steady entraining regime and the transient regime. The thermal burst theory proposes that the interface boundary layers become unstable and periodically break away due to the differing component diffusion rates. The quasi-steady entraining model assumes a thin interface where each burst entrains fluid up to the limit of neutral buoyancy. This entrainment assumption fixes the flux ratio at one and predicts normalized flux rates which are in generally good agreement with experimental data. The transient model assumes a thick interface with independent boundaries. There is no entrainment, but the boundary is reestablished after each burst at the point of neutral buoyancy. This assumption allows the model to predict interface growth and erosion rates. The transient model has been implemented in a finite difference simulation which has been used to recreate interface growth and erosion observed in experiments lasting as long as two weeks."
Type of Resource: text
Permalink: http://hdl.handle.net/2142/20808

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