fix cross-lines in implicit line agglomeration

Author: bigfooted

Common/src/geometry/CMultiGridGeometry.cpp

@@ -1106,6 +1106,30 @@ void CMultiGridGeometry::AgglomerateImplicitLines(unsigned long &Index_CoarseCV,
             !GeometricalCheck(c, fine_grid, config) || !GeometricalCheck(d, fine_grid, config))
           continue;
 
+
+        // Check for duplicate indices — guard against merging the same node twice.
+        if (a == b || a == c || a == d || b == c || b == d || c == d) {
+          if (debug) {
+            std::cout << "[MG_IMPLICIT] Duplicate indices detected in CROSS-LINE merge at stage " << pair_idx
+                      << " lines " << li1 << "," << li2 << " : indices = " << a << "," << b << "," << c
+                      << "," << d << "\n";
+            std::cout << "[MG_IMPLICIT] Parents: " << fine_grid->nodes->GetParent_CV(a) << ","
+                      << fine_grid->nodes->GetParent_CV(b) << "," << fine_grid->nodes->GetParent_CV(c) << ","
+                      << fine_grid->nodes->GetParent_CV(d) << "\n";
+            std::cout << "[MG_IMPLICIT] Reserved flags: " << reserved[a] << "," << reserved[b] << ","
+                      << reserved[c] << "," << reserved[d] << "\n";
+          } else {
+            std::cout << "[MG_IMPLICIT] Duplicate indices detected in CROSS-LINE merge; skipping merge for Index_CoarseCV="
+                      << Index_CoarseCV << "\n";
+          }
+
+          // Stop implicit-line agglomeration for other lines that share this parent
+          // so only one wall-line per parent is processed (prevents later conflicts).
+          for (auto other_li : entry.second) line_processed[other_li] = 1;
+
+          continue;
+        }
+
         // create a new coarse control volume merging {a,b,c,d}
         if (debug) {
           std::cout << "[MG_IMPLICIT] Stage " << pair_idx <<
@@ -1130,6 +1154,8 @@ void CMultiGridGeometry::AgglomerateImplicitLines(unsigned long &Index_CoarseCV,
 
         Index_CoarseCV++;
         line_processed[li1] = line_processed[li2] = 1;
+        // mark all other lines sharing this parent as processed (stop their implicit agglomeration)
+        for (auto other_li : line_ids) if (other_li != li1 && other_li != li2) line_processed[other_li] = 1;
         done_stage = false;
       }
     }

SU2_CFD/include/solvers/CScalarSolver.inl

@@ -132,7 +132,7 @@ void CScalarSolver<VariableType>::Upwind_Residual(CGeometry* geometry, CSolver**
   /*--- Define booleans that are solver specific through CConfig's GlobalParams which have to be set in CFluidIteration
    * before calling these solver functions. ---*/
   const bool implicit = (config->GetKind_TimeIntScheme() == EULER_IMPLICIT);
-  const bool muscl = config->GetMUSCL();
+  const bool muscl = config->GetMUSCL() && (iMesh == MESH_0);
   const bool limiter = (config->GetKind_SlopeLimit() != LIMITER::NONE) &&
                        (config->GetInnerIter() <= config->GetLimiterIter());
 

SU2_CFD/src/integration/CMultiGridIntegration.cpp

@@ -213,7 +213,7 @@ void CMultiGridIntegration::MultiGrid_Cycle(CGeometry ****geometry,
     /*--- Compute $P_(k+1) = I^(k+1)_k(r_k) - r_(k+1) ---*/
 
     // Adapt damping based on recorded pre-smoothing iterations and apply to forcing term
-    cout << "calling damp_restric_Adapt" << endl;
+    //cout << "calling damp_restric_Adapt" << endl;
     su2double adapted_factor = Damp_Restric_Adapt(lastPreSmoothIters, config->GetnMGLevels() + 1, config);
     SetForcing_Term(solver_fine, solver_coarse, geometry_fine, geometry_coarse, config, iMesh+1, adapted_factor);
 
@@ -775,7 +775,7 @@ static su2double Damp_Restric_Adapt(const unsigned short *lastPreSmoothIters,
   // already made through global MPI reductions, so calling the setter on all
   // ranks yields the same value everywhere.
   config->SetDamp_Res_Restric(new_factor);
-  cout << "ending Damp_Restric_Adapt, damping = " <<config->GetDamp_Res_Restric()  << endl;
+  //cout << "ending Damp_Restric_Adapt, damping = " <<config->GetDamp_Res_Restric()  << endl;
   return new_factor;
 }