From 3bd4b61ef91af620cbe9095282411e40c1168b91 Mon Sep 17 00:00:00 2001
From: Ping He <phe@iastate.edu>
Date: Sun, 7 Apr 2024 11:35:40 -0500
Subject: [PATCH] Fixed a potential issue for calcMeanStates. (#620)

---
 src/adjoint/DASolver/DASolver.C | 14 +++++++++++++-
 src/adjoint/DASolver/DASolver.H |  2 ++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/adjoint/DASolver/DASolver.C b/src/adjoint/DASolver/DASolver.C
index 44533e81..b4322bc8 100644
--- a/src/adjoint/DASolver/DASolver.C
+++ b/src/adjoint/DASolver/DASolver.C
@@ -9686,9 +9686,11 @@ void DASolver::assignMeanStatesToStates()
     /*
     Description:
         Assigned the calculated meanStates to the primal states and update intermediate vars 
+        NOTE: if meanStatesCalculated_ == 0, we will not assignMeanStatesToStates at the end of the primal.
+        meanStatesCalculated_ is assigned to 1 if timeIndex >= startTimeIndex in DASolver::calcMeanStates
     */
 
-    if (!useMeanStates_)
+    if (!useMeanStates_ || !meanStatesCalculated_)
     {
         return;
     }
@@ -9729,6 +9731,9 @@ void DASolver::assignMeanStatesToStates()
 
     // update state BC and intermedate vars
     this->updateStateBoundaryConditions();
+
+    // after the meanStates is assigned to states, reset meanStatesCalculated_ for the next primal solution.
+    meanStatesCalculated_ = 0;
 }
 
 void DASolver::calcMeanStates()
@@ -9809,6 +9814,13 @@ void DASolver::calcMeanStates()
                 }
             }
         }
+
+        // if we have caluclate mean states, i.e., timeIndex >= startTimeIndex, set meanStatesCalculated_ = 1
+        // this is to avoid setting a large startTime but the flow somehow converge before the startTime is
+        // triggered. In this case, the meanStates is never calculated and will return the wrong results
+        // if meanStatesCalculated_ == 0, we will not assignMeanStatesToStates at the end of the primal
+        // check DASolver::assignMeanStatesToStates
+        meanStatesCalculated_ = 1;
     }
 }
 
diff --git a/src/adjoint/DASolver/DASolver.H b/src/adjoint/DASolver/DASolver.H
index 492a98cd..d85a2950 100644
--- a/src/adjoint/DASolver/DASolver.H
+++ b/src/adjoint/DASolver/DASolver.H
@@ -209,6 +209,8 @@ protected:
     label useMeanStates_ = 0;
     /// if the meanStates is used, what is the step-averaging start
     scalar meanStateStart_ = 0.5;
+    /// whether we have calculated the meanStates, if not (flow converge before meanStateStart_), we will not use meanStates
+    label meanStatesCalculated_ = 0;
 
     /// step-averaged scalar states
     PtrList<volScalarField> meanVolScalarStates_;