Level set simulation of interface evolution due to model rime ice accretion
Date
1999
Authors
Khan, Sher Afgan
Major Professor
Advisor
Rothmayer, Alric Paul
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Abstract
The main focus of this paper is to track the interface which is generated due to rime ice accretion on the aircraft surfaces. The level set method which is relatively a new approach, is employed for tracking the motion of the interface. In level set method, the moving interface is modeled in Eulerian view instead of Lagrangian representation. The research is conducted to generate hyper surfaces from a distance function derived similar to the level set formulation. The hyper surfaces for NACA four digit airfoils have been generated. Also hyper surfaces for multiple bodies like an airfoil with a deflected flap and a slat have been constructed from the distance function. These hyper surfaces once generated are then taken as the interfaces and set to level zero. It is assumed that the initial interface defined by the geometry of the surface appears to be moving as the rime ice gets accumulated on it. A simple model, on the basis of conservation of mass for rime ice accretion is used to obtain the speed function.
The interface is then tracked by solving the modified level set equation within certain impingement limits. The impingement limits are defined as angle between the slope of water droplet trajectory and the hyper surface. The level set equation which is an initial value partial differential equation is numerically solved on the basis of hyperbolic conservation law with entropy satisfying condition. The numerical scheme followed is the one given by J.A. Sethian and S. Osher. The main focus of the project has been the application of level set method for tracking a moving interface. The results obtained are encouraging. The interface is advected with no diffusion or dissipation. The intersection of two interfaces is also quite smooth, as the entropy condition successfully accounts for the jump conditions at the discontinuity.
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thesis