[geomechanics] set default property value for enabling gravity

git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@14329 2fb0f335-1f38-0410-981e-8018bf24f1b0

dumux/geomechanics/elastic/elasticpropertydefaults.hh

@@ -75,6 +75,9 @@ SET_TYPE_PROP(BoxElastic, FluxVariables, ElasticFluxVariablesBase<TypeTag>);
 
 //! Set the indices used by the linear elasticity model
 SET_TYPE_PROP(BoxElastic, Indices, ElasticIndices<>);
+
+//! enable gravity by default
+SET_BOOL_PROP(BoxElastic, ProblemEnableGravity, true);
 }
 }