On Thu, May 12, 2022 at 3:28 AM Nick Olsen <n.olsen.3....@gmail.com> wrote:
> 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 If so, > 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. > Nils What you describe sounds isotropic. I assume that by saying "isotropic" you mean "spherically symmetric", i.e. the solution only depends on the radius r and not on the angles \theta or \phi. If so, then scalars should be the same in every direction, vectors should point in the radial direction, and tensors will look a bit more complicated. but "g_xx in the x direction is the same as g_zz in the z direction" sounds correct: If you rotate this tensor from the x to the z axis, then you're essentially exchanging x and z directions. The tensor itself does not need to remain spherically symmetric. (From your description above it sounds as if you assumed this was the case.) -erik > [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 > _______________________________________________ > Users mailing list > Users@einsteintoolkit.org > http://lists.einsteintoolkit.org/mailman/listinfo/users > -- Erik Schnetter <schnet...@gmail.com> http://www.perimeterinstitute.ca/personal/eschnetter/
_______________________________________________ Users mailing list Users@einsteintoolkit.org http://lists.einsteintoolkit.org/mailman/listinfo/users