[Users] Isotropic Initial Data Evolving Towards Anisotropy

[Nick Olsen]

Hello Everyone

I am running into a problem where I evolve a Gaussian shell scalar field
alongside the BSSN equations using the Scalar/ScalarInit/ScalarBase thorns,
where the initial data is isotropic but evolves to an anisotropic solution.
More specifically, along the x axis I have g_yy=g_zz and along the z axis I
have g_xx=g_yy, with g_xx along the x axis equal to g_zz along the z axis,
despite having isotropic initial conditions. The point is illustrated by
the first image being the plot of g_xx and g_zz along their respective axes
at a later time, and the rest of the diagonal metric values being shown in
the second image. Additionally, T_ij shows a similar problem, where T_xx
along the x axis and T_zz along the z axis are equal to eachother, but not
the rest of the diagonal entries of T_ij, which are all equal.
[image: gxxx.PNG][image: gxxz.PNG]
I have attached the parameter file used to get these results, which is a
modified version of the test parameter file found in the Scalar thorn
bundle.

Thanks,
Nicholas Olsen
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