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Modeling Thermal Convection Using Citcom 1 - Introduction |
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Thermal convection in planetary mantle is an important physical process that controls thermal evolution of terrestrial planets. Terrestrial planets contain radioactive heating in the mantle and primordial heating (i.e., resulted largely from the core formation). Thermal convection occurs in the mantle to release the heating and cool the planets. Tectonics and volcanisms are surface manifestations of this convective process. Mantle convection may take different forms for different planets. On Earth, mantle convection involves recycling of the surface or oceanic lithosphere and results in plate tectonics. Because the lithosphere is relatively cold, recycling the lithosphere represents an extremely efficient way to release the heat and cool the mantle. On Venus and Mars, mantle convection appears to occur below a thick stagnant lid with rather different characteristics. Mantle convection is a highly non-linear process with non-linear rheology and energy transfer. In this class project, we study basic characteristics of thermal convection by using a computer program called citcom. Citcom solves the conservation equations of the mass, energy, and momentum for thermal convection problems by using a finite element method. For this system of equations, there are two controling nondimensional parameters: Rayleign number Ra and internal heating rate H (Ra is a measure of vigor of convection). For a given Ra and H, citcom can be used to find heat flux at the surface and bottom boundary, flow velocity, temperature, and other important physical parameters. Citcom code was originally written in C by Dr. Louis Moresi as part of his thesis work at Oxford Univ and his post-doc work at Caltech. Many people including myself have used and worked to improve and enhance the code citcom, because of its flexibility, portability, and robustness. However, the version that you are going to use for your project is fairly similar to his original version. |
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