add linear dirichlet boundary condition as in Pipping-2013

dune/tectonic/problem-data/bc.hh

@@ -37,6 +37,39 @@ class VelocityDirichletCondition
   const double threshold_;
 };
 
+
+class VelocityDirichletConditionLinearLoading
+    : public Dune::VirtualFunction<double, double> {
+
+public:
+  VelocityDirichletConditionLinearLoading(const double finalVelocity = 5e-5, const double threshold = 0.1) :
+      finalVelocity_(finalVelocity),
+      threshold_(threshold)
+  {}
+
+  void evaluate(double const &relativeTime, double &y) const {
+    // Assumed to vanish at time zero
+
+    //std::cout << "VelocityDirichletCondition::evaluate()" << std::endl;
+
+    /*if (relativeTime <= 0.1)
+        std::cout << "- loading phase" << std::endl;
+    else
+        std::cout << "- final velocity reached" << std::endl;*/
+
+    y = (relativeTime <= threshold_)
+            ? finalVelocity_ * relativeTime / threshold_
+            : finalVelocity_;
+
+    //y = relativeTime * finalVelocity;
+
+  }
+
+private:
+  const double finalVelocity_;
+  const double threshold_;
+};
+
 class VelocityStepDirichletCondition
     : public Dune::VirtualFunction<double, double> {