[cig-commits] [commit] devel: added more details about PML to the manual (about regular elements inside the PMLs for better time stability) (783b2cd)

[cig_noreply at geodynamics.org]

Repository : https://github.com/geodynamics/specfem3d

On branch  : devel
Link       : https://github.com/geodynamics/specfem3d/compare/4720296dd98ef99c70e9ad3d9fd6fc550475f60b...367727d9b25a3dc40b9c10fee9dc3275eff7b717

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commit 783b2cdc0a7434927200c1b08b1ed160ffa291d4
Author: Dimitri Komatitsch <komatitsch at lma.cnrs-mrs.fr>
Date:   Tue Jan 27 01:43:03 2015 +0100

    added more details about PML to the manual (about regular elements inside the PMLs for better time stability)


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783b2cdc0a7434927200c1b08b1ed160ffa291d4
 doc/USER_MANUAL/manual_SPECFEM3D_Cartesian.pdf | Bin 14049638 -> 14050378 bytes
 doc/USER_MANUAL/manual_SPECFEM3D_Cartesian.tex |   7 +++++++
 2 files changed, 7 insertions(+)

diff --git a/doc/USER_MANUAL/manual_SPECFEM3D_Cartesian.pdf b/doc/USER_MANUAL/manual_SPECFEM3D_Cartesian.pdf
index 7c40a59..ab2f74d 100644
Binary files a/doc/USER_MANUAL/manual_SPECFEM3D_Cartesian.pdf and b/doc/USER_MANUAL/manual_SPECFEM3D_Cartesian.pdf differ
diff --git a/doc/USER_MANUAL/manual_SPECFEM3D_Cartesian.tex b/doc/USER_MANUAL/manual_SPECFEM3D_Cartesian.tex
index a391639..701c7ca 100644
--- a/doc/USER_MANUAL/manual_SPECFEM3D_Cartesian.tex
+++ b/doc/USER_MANUAL/manual_SPECFEM3D_Cartesian.tex
@@ -1837,6 +1837,13 @@ model will change from viscoelastic or poroelastic to elastic at the
 entrance of the PML, but in practice this is sufficient and produces
 only tiny / negligible spurious reflections.
 
+If you use PML and an external mesh (created using an external meshing tool 
+such as CUBIT/TRELIS or similar), try to have elements inside the PML as regular as possible, 
+i.e. ideally non-deformed cubes obtained by `extrusion' of regular surface mesh elements meshing the
+outer edges of the computational domain without PML; by doing so, the PMLs obtained will be far more stable
+in time (PML being weakly unstable from a mathematical point of view, very deformed mesh elements
+inside the PMLs can trigger instabilities much more quickly).
+
 If you use PML and an external tomographic velocity and density model,
 you should be careful because mathematically a PML cannot handle heterogeneities
 along the normal to the PML edge inside the PML layer. This comes