[cig-commits] [commit] devel: added a test for negative relaxation times for attenuation memory variables (c9f16d3)

[cig_noreply at geodynamics.org]

Repository : https://github.com/geodynamics/specfem2d

On branch  : devel
Link       : https://github.com/geodynamics/specfem2d/compare/4cdd38362398e4d37b8bf66655dff04e7eb786f5...9d9b2de9c3104b1987b606b127da578c273ab0f4

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commit c9f16d302bacf3bb3fd87e69a8b46691d1c12048
Author: Dimitri Komatitsch <komatitsch at lma.cnrs-mrs.fr>
Date:   Mon May 26 22:37:36 2014 +0200

    added a test for negative relaxation times for attenuation memory variables


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c9f16d302bacf3bb3fd87e69a8b46691d1c12048
 src/specfem2D/attenuation_model.f90 | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/specfem2D/attenuation_model.f90 b/src/specfem2D/attenuation_model.f90
index 2ea6580..898b4eb 100644
--- a/src/specfem2D/attenuation_model.f90
+++ b/src/specfem2D/attenuation_model.f90
@@ -72,6 +72,12 @@
        f1_attenuation,f2_attenuation, &
        tau_sigma_nu1, tau_sigma_nu2, tau_epsilon_nu1, tau_epsilon_nu2)
 
+! make sure no negative relaxation times have been found; Emmerich and Korn (1987) or similar
+! can sometimes lead to negative values for very small values of Q (i.e. very high attenuation, say Q = 5 or Q = 10 or so)
+  if(minval(tau_sigma_nu1) <= 0.d0 .or. minval(tau_sigma_nu2) <= 0.d0 .or. &
+     minval(tau_epsilon_nu1) <= 0.d0 .or.  minval(tau_epsilon_nu2) <= 0.d0) &
+       stop 'error: negative relaxation time found, the code will be unstable'
+
 ! attenuation constants for standard linear solids
 
 ! nu1 is the dilatation/incompressibility mode (QKappa)