From 8b4bd214b622ff7acda33eef4a2b647b6d6c0290 Mon Sep 17 00:00:00 2001
From: Malachi <malachi2@illinois.edu>
Date: Mon, 27 Jul 2020 11:46:35 -0500
Subject: [PATCH] Enable usage of residual projection for velocity solvers
 (#122) (#123)

---
 src/core/insSetup.cpp  |  3 +++
 src/core/parReader.cpp | 19 +++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/src/core/insSetup.cpp b/src/core/insSetup.cpp
index 5535a10ad..5bb457586 100644
--- a/src/core/insSetup.cpp
+++ b/src/core/insSetup.cpp
@@ -317,6 +317,9 @@ ins_t* insSetup(MPI_Comm comm, occa::device device, setupAide &options, int buil
     ins->vOptions.setArgs("DISCRETIZATION",       options.getArgs("VELOCITY DISCRETIZATION"));
     ins->vOptions.setArgs("BASIS",                options.getArgs("VELOCITY BASIS"));
     ins->vOptions.setArgs("PRECONDITIONER",       options.getArgs("VELOCITY PRECONDITIONER"));
+    ins->vOptions.setArgs("RESIDUAL PROJECTION",       options.getArgs("VELOCITY RESIDUAL PROJECTION"));
+    ins->vOptions.setArgs("RESIDUAL PROJECTION VECTORS",       options.getArgs("VELOCITY RESIDUAL PROJECTION VECTORS"));
+    ins->vOptions.setArgs("RESIDUAL PROJECTION START",       options.getArgs("VELOCITY RESIDUAL PROJECTION START"));
     ins->vOptions.setArgs("MULTIGRID COARSENING", options.getArgs("VELOCITY MULTIGRID COARSENING"));
     ins->vOptions.setArgs("MULTIGRID SMOOTHER",   options.getArgs("VELOCITY MULTIGRID SMOOTHER"));
     ins->vOptions.setArgs("MULTIGRID CHEBYSHEV DEGREE",
diff --git a/src/core/parReader.cpp b/src/core/parReader.cpp
index 3c64b1b36..39b9bddcd 100644
--- a/src/core/parReader.cpp
+++ b/src/core/parReader.cpp
@@ -53,6 +53,9 @@ void setDefaultSettings(libParanumal::setupAide &options, string casename, int r
   options.setArgs("VELOCITY BASIS", "NODAL");
   options.setArgs("VELOCITY PRECONDITIONER", "JACOBI");
   options.setArgs("VELOCITY DISCRETIZATION", "CONTINUOUS");
+  options.setArgs("VELOCITY RESIDUAL PROJECTION", "FALSE");
+  options.setArgs("VELOCITY RESIDUAL PROJECTION VECTORS", "8");
+  options.setArgs("VELOCITY RESIDUAL PROJECTION START", "5");
 
   options.setArgs("VARIABLE VISCOSITY", "FALSE");
   options.setArgs("LOWMACH", "FALSE");
@@ -452,12 +455,28 @@ libParanumal::setupAide parRead(std::string &setupFile, MPI_Comm comm)
 
     string vsolver;
     int flow = 1;
+    bool v_rproj;
+    if(ini.extract("velocity", "residualproj", v_rproj)) {
+      if(v_rproj)
+        options.setArgs("VELOCITY RESIDUAL PROJECTION", "TRUE");
+      else
+        options.setArgs("VELOCITY RESIDUAL PROJECTION", "FALSE");
+
+      int v_nProjVec;
+      if(ini.extract("velocity", "residualprojectionvectors", v_nProjVec))
+        options.setArgs("VELOCITY RESIDUAL PROJECTION VECTORS", std::to_string(v_nProjVec));
+      int v_nProjStep;
+      if(ini.extract("velocity", "residualprojectionstart", v_nProjStep))
+        options.setArgs("VELOCITY RESIDUAL PROJECTION START", std::to_string(v_nProjStep));
+    }
     ini.extract("velocity", "solver", vsolver);
     if(vsolver == "none") {
       options.setArgs("VELOCITY SOLVER", "NONE");
       flow = 0;
     } else if(std::strstr(vsolver.c_str(), "block")) {
       options.setArgs("VELOCITY BLOCK SOLVER", "TRUE");
+      if(options.compareArgs("VELOCITY RESIDUAL PROJECTION","TRUE"))
+        exit("Residual projection is not enabled for the velocity block solver!", EXIT_FAILURE);
     }
 
     double v_residualTol;