Add comments about the need for communication to the assemble functions of MultisegmentWellAssemble

opm/simulators/wells/MultisegmentWellAssemble.cpp

@@ -96,6 +96,10 @@ assembleControlEq(const WellState<Scalar>& well_state,
                   const bool stopped_or_zero_target,
                   DeferredLogger& deferred_logger) const
 {
+    /*
+        This function assembles the control equation, similar as for StandardWells.
+        It does *not* need communication.
+    */
     static constexpr int Gas = BlackoilPhases::Vapour;
     static constexpr int Oil = BlackoilPhases::Liquid;
     static constexpr int Water = BlackoilPhases::Aqua;
@@ -212,6 +216,12 @@ assembleAccelerationTerm(const int seg_target,
     // acceleration term shold be
     //  * velocity head for seg_target if seg = seg_target
     //  * negative velocity head for seg if seg != seg_target   
+    
+    /*
+        This method is called in MultisegmentWellEval::assembleAccelerationPressureLoss.
+        It does *not* need communication.
+    */
+
     MultisegmentWellEquationAccess<Scalar,numWellEq,Indices::numEq> eqns(eqns1);
     eqns.residual()[seg_target][SPres] -= accelerationTerm.value();
     eqns.D()[seg_target][seg][SPres][SPres] -= accelerationTerm.derivative(SPres + Indices::numEq);
@@ -231,6 +241,11 @@ assembleHydroPressureLoss(const int seg,
                           const EvalWell& hydro_pressure_drop_seg,
                           Equations& eqns1) const
 {
+    /*
+        This method is called in MultisegmentWellEval::assembleAccelerationAndHydroPressureLosses.
+        It does *not* need communication.
+    */
+
     MultisegmentWellEquationAccess<Scalar,numWellEq,Indices::numEq> eqns(eqns1);
     eqns.residual()[seg][SPres] -= hydro_pressure_drop_seg.value();
     for (int pv_idx = 0; pv_idx < numWellEq; ++pv_idx) {
@@ -246,6 +261,9 @@ assemblePressureEqExtraDerivatives(const int seg,
                                    const EvalWell& extra_derivatives,
                                    Equations& eqns1) const
 {
+    /*
+        This method does *not* need communication.
+    */
     MultisegmentWellEquationAccess<Scalar,numWellEq,Indices::numEq> eqns(eqns1);
     // disregard residual
     // Frac - derivatives are zero (they belong to upwind^2)
@@ -265,6 +283,9 @@ assemblePressureEq(const int seg,
                    bool wfrac,
                    bool gfrac) const
 {
+    /*
+        This method does *not* need communication.
+    */
     MultisegmentWellEquationAccess<Scalar,numWellEq,Indices::numEq> eqns(eqns1);
     eqns.residual()[seg][SPres] += pressure_equation.value();
     eqns.D()[seg][seg][SPres][SPres] += pressure_equation.derivative(SPres + Indices::numEq);
@@ -289,6 +310,13 @@ assembleTrivialEq(const int seg,
                   const Scalar value,
                   Equations& eqns1) const
 {
+    /*
+        This method is called from MultisegmentWellEval::assembleICDPressureEq,
+        which is called from MultisegmentWellEval::assemblePressureEq.
+        This is the counterpart to assembleControlEquation, where assembleControlEquation is responsible for the top segment
+        and assembleICDPressureEq is responsible for the remaining segments.
+        This method does *not* need communication.
+    */
     MultisegmentWellEquationAccess<Scalar,numWellEq,Indices::numEq> eqns(eqns1);
     eqns.residual()[seg][SPres] = value;
     eqns.D()[seg][seg][SPres][WQTotal] = 1.;
@@ -301,6 +329,10 @@ assembleAccumulationTerm(const int seg,
                          const EvalWell& accumulation_term,
                          Equations& eqns1) const
 {
+    /*
+        This method is called from MultisegmentWell::assembleWellEqWithoutIteration.
+        It only assembles on the diagonal of D and it does *not* need communication.
+    */
     MultisegmentWellEquationAccess<Scalar,numWellEq,Indices::numEq> eqns(eqns1);
     eqns.residual()[seg][comp_idx] += accumulation_term.value();
     for (int pv_idx = 0; pv_idx < numWellEq; ++pv_idx) {
@@ -316,6 +348,10 @@ assembleOutflowTerm(const int seg,
                     const EvalWell& segment_rate,
                     Equations& eqns1) const
 {
+    /*
+        This method is called from MultisegmentWell::assembleWellEqWithoutIteration.
+        It does *not* need communication.
+    */
     MultisegmentWellEquationAccess<Scalar,numWellEq,Indices::numEq> eqns(eqns1);
     eqns.residual()[seg][comp_idx] -= segment_rate.value();
     eqns.D()[seg][seg][comp_idx][WQTotal] -= segment_rate.derivative(WQTotal + Indices::numEq);
@@ -337,6 +373,10 @@ assembleInflowTerm(const int seg,
                    const EvalWell& inlet_rate,
                    Equations& eqns1) const
  {
+    /*
+        This method is called from MultisegmentWell::assembleWellEqWithoutIteration.
+        It does *not* need communication.
+    */
     MultisegmentWellEquationAccess<Scalar,numWellEq,Indices::numEq> eqns(eqns1);
     eqns.residual()[seg][comp_idx] += inlet_rate.value();
     eqns.D()[seg][inlet][comp_idx][WQTotal] += inlet_rate.derivative(WQTotal + Indices::numEq);
@@ -357,6 +397,12 @@ assemblePerforationEq(const int seg,
                       const EvalWell& cq_s_effective,
                       Equations& eqns1) const
 {
+    /*
+        This method is called from MultisegmentWell::assembleWellEqWithoutIteration.
+        It *does* need communication, i.e. this method only assembles the parts of the matrix this process is responsible for
+        and after calling this function, the diagonal of the matrix D and the residual need to be combined by calling
+        the function MultisegmentWellEquations::sumDistributed.
+    */
     MultisegmentWellEquationAccess<Scalar,numWellEq,Indices::numEq> eqns(eqns1);
     // subtract sum of phase fluxes in the well equations.
     eqns.residual()[seg][comp_idx] += cq_s_effective.value();