Author: Akira Kageyama and Masaki Yoshida
Title: "Development of new simulation code for core/mantle convection by Yin-Yang grid"

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key words: geodynamo, mantle convection, Yin-Yang grid
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abstract
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To make the best use of the Earth
Simulator, which is the world's fastest
supercomputer today, we are developing a new grid
system for the spherical geometry named Yin-Yang
Grid.  The Yin-Yang Grid is a kind of the overset or
Chimera grid system, in which multiple coordinates
are partially overlapped each other at their
interfaces, covering all simulation region as
a whole.  In the Yin-Yang Grid, we combine two
identical grid systems (Yin and Yang) to cover the
a spherical surface.  The Yin or Yang grid is
nothing but a part (roughly a half) of the usual
spherical, or latitude-longitude coordinates.
The idea of the Yin-Yang grid has come from the
observation that low latitude part of the
latitude-longitude grid has nice properties as the
simulation grid on the sphere: It has no
coordinate singularity; the grid distribution is
nearly uniform; and it is orthogonal. In
addition to these basic features, Yin-Yang
grid is devised from the beginning as a proper
grid system for the vector-parallel architecture
computers such as the Earth Simulator: Spatial
decomposition for parallel processing is
relatively easy and efficient with keeping high
vectorization rate.  Based on the Yin-Yang grid,
we are developing new simulation codes for
the core convection and the mantle convection.
Some preliminary results will be presented in the talk.