Thorsten W. Becker

Jackson School of Geosciences
The University of Texas at Austin

Teaching: Thermal convection


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teaching: UT GEOL: [303], [371]; other classes
[CIDER] [C] [UNIX/GMT] [SEATREE] [visuals]

Thermal convection in 2-D movies

The following movies show thermal convection in the infinite Prandl number, laminar flow limit as appropriate for the Earth's mantle. The movies were produced for educational purposes with the finite element code ConMan by Scott King, and the finite difference code FDCON by Harro Schmeling

Isoviscous models

The aspect ratio of the computational domain is four (4 x 1 , 2D), there is no internal heating, fixed thermal boundary conditions on the top and bottom (heating from below) and free slip along the boundaries.

The time you see in the title is in nodimensional units and has to be multiplied by the conductive timescale for real times.

  • Rayleigh number 10^6
    Quicktime movie (940kB). Note how an initial disturbance evolves into stable convection cells and the conductive temperature profile changes. At the end, the system has reached quasi steady-state.

  • Rayleigh number 10^7, initial condition 1
    Quicktime movie (2.7MB). Starting from a disturbance, an apparently stable configuration with higher wavelength than for Ra=10^6 develops. It is only temporarily stable, however, as can be seen later when the time-dependence takes over.

  • Rayleigh number 10^7, initial condition 2
    Quicktime movie (900kB). The same model as above develops into time-dependence right away from different initial conditions.

Temperature dependent convection

Under construction, send me email if you are interested in the visualizations shown in class.

Subduction

A dense, fluid slab sinks into the upper mantle. The rheology is Newtonian, besides near the surface, where a "Byerlee law" reduces the material strength, simulating plastic deformation (see Enns et al., 2005, for an equialent, 2-D setup and details). The box is meant to simulate the upper 1000 km of the mantle; slab thickness is 100 km and slab viscosity is 500 times the mantle viscosity. Computed using L. Moresi's Citcom FE code with extensions by S. Zhong, as provided by CIG.

Other links

See also Shijie Zhong's nice Virtual Earth online thermal convection module at CU Boulder and a collection of links to more movies on my 440 course web page.
Updated: June 14, 2019 (c) JSG Geodynamics, 2019.