Added an option to use step-averaged states for steady-state solvers. (#613)

Author: friedenhe

dafoam/pyDAFoam.py

@@ -527,6 +527,19 @@ def __init__(self):
             "defaultOutputValue": 0.0,
         }
 
+        ## whether to use averaged states
+        ## This is useful for cases when steady-state solvers do not converge very well, e.g., flow
+        ## separation. In these cases, the flow field and the objective function will oscillate and
+        ## to get a better flow field and obj func value, we can use step-averaged (mean) states
+        ## the start can be from 0 to 1. 0 means we use all time steps for averaging, while 1 means
+        ## we use no time steps for averaging. 0.8 means we use the last 20% of the time step for averaging.
+        ## We usually don't use 0 because the flow will need some spin up time, so using the spin-up
+        ## flow field for meanStates will be slightly inaccurate.
+        self.useMeanStates = {
+            "active": False,
+            "start": 0.5
+        }
+
         # *********************************************************************************************
         # ************************************ Advance Options ****************************************
         # *********************************************************************************************

src/adjoint/DASolver/DARhoSimpleCFoam/DARhoSimpleCFoam.C

@@ -132,6 +132,8 @@ label DARhoSimpleCFoam::solvePrimal(
     // check if the parameters are set in the Python layer
     daRegressionPtr_->validate();
 
+    // if useMeanStates is used, we need to zero meanStates before the primal run
+    this->zeroMeanStates();
 
     label printInterval = daOptionPtr_->getOption<label>("printInterval");
     label printToScreen = 0;
@@ -181,6 +183,9 @@ label DARhoSimpleCFoam::solvePrimal(
                  << nl << endl;
         }
 
+        // if useMeanStates is used, we need to calculate the meanStates
+        this->calcMeanStates();
+
         runTime.write();
     }
 
@@ -189,6 +194,9 @@ label DARhoSimpleCFoam::solvePrimal(
         return 1;
     }
 
+    // if useMeanStates is used, we need to assign meanStates to states right after the case converges
+    this->assignMeanStatesToStates();
+
     this->calcPrimalResidualStatistics("print");
 
     // primal converged, assign the OpenFoam fields to the state vec wVec

src/adjoint/DASolver/DARhoSimpleFoam/DARhoSimpleFoam.C

@@ -149,6 +149,9 @@ label DARhoSimpleFoam::solvePrimal(
     // check if the parameters are set in the Python layer
     daRegressionPtr_->validate();
 
+    // if useMeanStates is used, we need to zero meanStates before the primal run
+    this->zeroMeanStates();
+
     label printInterval = daOptionPtr_->getOption<label>("printInterval");
     label printToScreen = 0;
     label regModelFail = 0;
@@ -197,6 +200,9 @@ label DARhoSimpleFoam::solvePrimal(
                  << nl << endl;
         }
 
+        // if useMeanStates is used, we need to calculate the meanStates
+        this->calcMeanStates();
+
         runTime.write();
     }
 
@@ -205,6 +211,9 @@ label DARhoSimpleFoam::solvePrimal(
         return 1;
     }
 
+    // if useMeanStates is used, we need to assign meanStates to states right after the case converges
+    this->assignMeanStatesToStates();
+
     this->writeAssociatedFields();
 
     this->calcPrimalResidualStatistics("print");

src/adjoint/DASolver/DASimpleFoam/DASimpleFoam.C

@@ -160,6 +160,9 @@ label DASimpleFoam::solvePrimal(
     // check if the parameters are set in the Python layer
     daRegressionPtr_->validate();
 
+    // if useMeanStates is used, we need to zero meanStates before the primal run
+    this->zeroMeanStates();
+
     label printInterval = daOptionPtr_->getOption<label>("printInterval");
     label printToScreen = 0;
     label regModelFail = 0;
@@ -209,6 +212,9 @@ label DASimpleFoam::solvePrimal(
                  << nl << endl;
         }
 
+        // if useMeanStates is used, we need to calculate the meanStates
+        this->calcMeanStates();
+
         runTime.write();
     }
 
@@ -217,6 +223,9 @@ label DASimpleFoam::solvePrimal(
         return 1;
     }
 
+    // if useMeanStates is used, we need to assign meanStates to states right after the case converges
+    this->assignMeanStatesToStates();
+
     this->writeAssociatedFields();
 
     this->calcPrimalResidualStatistics("print");

src/adjoint/DASolver/DASimpleTFoam/DASimpleTFoam.C

@@ -139,6 +139,9 @@ label DASimpleTFoam::solvePrimal(
     // check if the parameters are set in the Python layer
     daRegressionPtr_->validate();
 
+    // if useMeanStates is used, we need to zero meanStates before the primal run
+    this->zeroMeanStates();
+
     label printInterval = daOptionPtr_->getOption<label>("printInterval");
     label printToScreen = 0;
     label regModelFail = 0;
@@ -189,6 +192,9 @@ label DASimpleTFoam::solvePrimal(
                  << nl << endl;
         }
 
+        // if useMeanStates is used, we need to calculate the meanStates
+        this->calcMeanStates();
+
         runTime.write();
     }
 
@@ -197,6 +203,9 @@ label DASimpleTFoam::solvePrimal(
         return 1;
     }
 
+    // if useMeanStates is used, we need to assign meanStates to states right after the case converges
+    this->assignMeanStatesToStates();
+
     this->calcPrimalResidualStatistics("print");
 
     // primal converged, assign the OpenFoam fields to the state vec wVec