Added debug output

src/vrm.f90

@@ -264,6 +264,18 @@ select case (trim(plasticity_type))
     fail  = 2.d0*viscosity*e2d-yield
     if (fail.gt.0.d0) then
       viscosity=0.5d0*yield/e2d
+      if (viscosity.le.params%viscositymin) then
+        write(*,*) 'VISCOSITY BELOW MINIMUM'
+        write(*,*) 'viscosity: ',viscosity
+        write(*,*) 'yield: ',yield
+        write(*,*) 'fail: ',fail
+        write(*,*) '-pressure: ',-pressure
+        write(*,*) 'sin_phi: ',sin_phi
+        write(*,*) 'c: ',c
+        write(*,*) 'cos_phi: ',cos_phi
+        write(*,*) 'zeta: ',zeta
+        write(*,*) 'e2d: ',e2d
+      endif
       is_plastic=.true.
     else
       is_plastic=.false.