From 99421f77f85e91262f921cf0bbdc3724d0a9cb20 Mon Sep 17 00:00:00 2001
From: David Schneider <david.schneider@ipvs.uni-stuttgart.de>
Date: Tue, 28 Nov 2023 10:34:05 +0100
Subject: [PATCH] Re arrange read time according to adjustable dt (#298)

Co-authored-by: Gerasimos Chourdakis <chourdak@in.tum.de>
---
 Adapter.C                | 30 +++++++++++++++---------------
 Adapter.H                |  3 ++-
 changelog-entries/298.md |  1 +
 3 files changed, 18 insertions(+), 16 deletions(-)
 create mode 100644 changelog-entries/298.md

diff --git a/Adapter.C b/Adapter.C
index f49f8f80..b92f3d00 100644
--- a/Adapter.C
+++ b/Adapter.C
@@ -363,9 +363,6 @@ void preciceAdapter::Adapter::configure()
         // Initialize preCICE and exchange the first coupling data
         initialize();
 
-        // Read the received coupling data
-        readCouplingData(runTime_.deltaT().value());
-
         // If checkpointing is required, specify the checkpointed fields
         // and write the first checkpoint
         if (requiresWritingCheckpoint())
@@ -382,7 +379,7 @@ void preciceAdapter::Adapter::configure()
         // Adjust the timestep for the first iteration, if it is fixed
         if (!adjustableTimestep_)
         {
-            adjustSolverTimeStep();
+            adjustSolverTimeStepAndReadData();
         }
 
         // If the solver tries to end before the coupling is complete,
@@ -443,12 +440,6 @@ void preciceAdapter::Adapter::execute()
         readCheckpoint();
     }
 
-    // Adjust the timestep, if it is fixed
-    if (!adjustableTimestep_)
-    {
-        adjustSolverTimeStep();
-    }
-
     // Write checkpoint if required
     if (requiresWritingCheckpoint())
     {
@@ -476,9 +467,11 @@ void preciceAdapter::Adapter::execute()
     }
     ACCUMULATE_TIMER(timeInWriteResults_);
 
-    // Read the received coupling data from the buffer
-    // Fits to an implicit Euler
-    readCouplingData(runTime_.deltaT().value());
+    // Adjust the timestep, if it is fixed
+    if (!adjustableTimestep_)
+    {
+        adjustSolverTimeStepAndReadData();
+    }
 
     // If the coupling is not going to continue, tear down everything
     // and stop the simulation.
@@ -507,9 +500,10 @@ void preciceAdapter::Adapter::execute()
     return;
 }
 
+
 void preciceAdapter::Adapter::adjustTimeStep()
 {
-    adjustSolverTimeStep();
+    adjustSolverTimeStepAndReadData();
 
     return;
 }
@@ -599,7 +593,7 @@ void preciceAdapter::Adapter::advance()
     return;
 }
 
-void preciceAdapter::Adapter::adjustSolverTimeStep()
+void preciceAdapter::Adapter::adjustSolverTimeStepAndReadData()
 {
     DEBUG(adapterInfo("Adjusting the solver's timestep..."));
 
@@ -695,6 +689,12 @@ void preciceAdapter::Adapter::adjustSolverTimeStep()
     // TODO: Keep this in mind if any relevant problem appears.
     const_cast<Time&>(runTime_).setDeltaT(timestepSolver_, false);
 
+    DEBUG(adapterInfo("Reading coupling data associated to the calculated time-step size..."));
+
+    // Read the received coupling data from the buffer
+    // Fits to an implicit Euler
+    readCouplingData(runTime_.deltaT().value());
+
     return;
 }
 
diff --git a/Adapter.H b/Adapter.H
index 2112898b..671c947f 100644
--- a/Adapter.H
+++ b/Adapter.H
@@ -271,7 +271,8 @@ private:
     void writeCouplingData();
 
     //- Adjust the timestep of the solver according to preCICE
-    void adjustSolverTimeStep();
+    // and read data associated to the calculated time step length
+    void adjustSolverTimeStepAndReadData();
 
     //- Determine if the coupling is still happening
     bool isCouplingOngoing();
diff --git a/changelog-entries/298.md b/changelog-entries/298.md
new file mode 100644
index 00000000..8163f04b
--- /dev/null
+++ b/changelog-entries/298.md
@@ -0,0 +1 @@
+- Renamed the `adjustSolverTimeStep()` method to `adjustSolverTimeStepAndReadData()`, changing the behavior to always read data at the determined time step size. [#298](https://github.com/precice/openfoam-adapter/pull/298)