Enforce recomputation of preconditioner to avoid regression (#634)

Author: uekerman

changelog-entries/634.md

@@ -0,0 +1 @@
+- Changed the IQN settings in the elastic-tube-1d and perpendicular flap tutorials to enforce recomputation of the preconditioner [#634](https://github.com/precice/tutorials/pull/634)

elastic-tube-1d/precice-config.xml

@@ -63,6 +63,7 @@
     <acceleration:IQN-ILS>
       <data name="CrossSectionLength" mesh="Solid-Nodes-Mesh" />
       <initial-relaxation value="0.01" />
+      <preconditioner type="residual-sum" update-on-threshold="false" />
       <max-used-iterations value="50" />
       <time-windows-reused value="8" />
       <filter type="QR2" limit="1e-3" />

perpendicular-flap/precice-config.xml

@@ -56,7 +56,7 @@
     <acceleration:IQN-ILS>
       <data name="Displacement" mesh="Solid-Mesh" />
       <data name="Force" mesh="Solid-Mesh" />
-      <preconditioner type="residual-sum" />
+      <preconditioner type="residual-sum" update-on-threshold="false" />
       <filter type="QR2" limit="1e-2" />
       <initial-relaxation value="0.5" />
       <max-used-iterations value="100" />