closes idaholab#16474

framework/include/problems/FEProblemBase.h

@@ -1915,6 +1915,15 @@ class FEProblemBase : public SubProblem, public Restartable
     _n_max_nl_pingpong = n_max_nl_pingpong;
   }
 
+  /// method setting the minimum number of nonlinear iterations before performing divergence checks
+  void setNLForcedIterations(const unsigned int nl_forced_its) { _nl_forced_its = nl_forced_its; }
+
+  /// method setting the absolute divergence tolerance
+  void setNLAbsoluteDivergenceTolerance(const Real abs_nl_divtol)
+  {
+    _abs_nl_divtol = abs_nl_divtol;
+  }
+
 protected:
   /// Create extra tagged vectors and matrices
   void createTagVectors();
@@ -1941,6 +1950,12 @@ class FEProblemBase : public SubProblem, public Restartable
   unsigned int _n_nl_pingpong = 0;
   unsigned int _n_max_nl_pingpong = std::numeric_limits<unsigned int>::max();
 
+  /// the number of forced nonlinear iterations
+  int _nl_forced_its = 0;
+
+  /// the absolute non linear divergnce tolerance
+  Real _abs_nl_divtol = -1;
+
   std::shared_ptr<NonlinearSystemBase> _nl;
   std::shared_ptr<AuxiliarySystem> _aux;
 

framework/src/executioners/FEProblemSolve.C

@@ -68,10 +68,19 @@ FEProblemSolve::validParams()
   params.addParam<Real>("l_abs_tol", 1.0e-50, "Linear Absolute Tolerance");
   params.addParam<unsigned int>("l_max_its", 10000, "Max Linear Iterations");
   params.addParam<unsigned int>("nl_max_its", 50, "Max Nonlinear Iterations");
+  params.addParam<unsigned int>(
+      "nl_forced_its", 0, "The number of nonlinear iteration before performing divergence checks");
   params.addParam<unsigned int>("nl_max_funcs", 10000, "Max Nonlinear solver function evaluations");
   params.addParam<Real>("nl_abs_tol", 1.0e-50, "Nonlinear Absolute Tolerance");
   params.addParam<Real>("nl_rel_tol", 1.0e-8, "Nonlinear Relative Tolerance");
-  params.addParam<Real>("nl_div_tol", 1.0e10, "Nonlinear Divergence Tolerance");
+  params.addParam<Real>(
+      "nl_div_tol",
+      1.0e10,
+      "Nonlinear Relative Divergence Tolerance. A negative value disables this check.");
+  params.addParam<Real>(
+      "nl_abs_div_tol",
+      1.0e50,
+      "Nonlinear Absolute Divergence Tolerance. A negative value disables this check.");
   params.addParam<Real>("nl_abs_step_tol", 0., "Nonlinear Absolute step Tolerance");
   params.addParam<Real>("nl_rel_step_tol", 0., "Nonlinear Relative step Tolerance");
   params.addParam<unsigned int>(
@@ -176,6 +185,10 @@ FEProblemSolve::FEProblemSolve(Executioner * ex)
 
   _problem.setMaxNLPingPong(getParam<unsigned int>("n_max_nonlinear_pingpong"));
 
+  _problem.setNLForcedIterations(getParam<unsigned int>("nl_forced_its"));
+
+  _problem.setNLAbsoluteDivergenceTolerance(getParam<Real>("nl_abs_div_tol"));
+
   _nl.setDecomposition(_splitting);
 }
 

framework/src/problems/FEProblemBase.C

@@ -6700,13 +6700,19 @@ FEProblemBase::checkNonlinearConvergence(std::string & msg,
           << '\n';
       reason = MooseNonlinearConvergenceReason::CONVERGED_SNORM_RELATIVE;
     }
-    else if (divtol > 0 && fnorm > the_residual * divtol)
+    else if (divtol > 0 && it >= _nl_forced_its && fnorm > the_residual * divtol)
     {
       oss << "Diverged due to initial residual " << the_residual << " > divergence tolerance "
           << divtol << " * initial residual " << the_residual << '\n';
       reason = MooseNonlinearConvergenceReason::DIVERGED_DTOL;
     }
-    else if (_n_nl_pingpong > _n_max_nl_pingpong)
+    else if (_abs_nl_divtol > 0 && it >= _nl_forced_its && fnorm > _abs_nl_divtol)
+    {
+      oss << "Diverged due to residual " << fnorm << " > absolute divergence tolerance "
+          << _abs_nl_divtol << '\n';
+      reason = MooseNonlinearConvergenceReason::DIVERGED_DTOL;
+    }
+    else if (it >= _nl_forced_its && _n_nl_pingpong > _n_max_nl_pingpong)
     {
       oss << "Diverged due to maximum non linear residual pingpong achieved" << '\n';
       reason = MooseNonlinearConvergenceReason::DIVERGED_NL_RESIDUAL_PINGPONG;

test/tests/executioners/nl_divergence_tolerance/nl_abs_divergence_tolerance.i

@@ -0,0 +1,63 @@
+[Mesh]
+  type = GeneratedMesh
+  dim = 2
+  nx = 15
+  ny = 15
+[]
+
+[Variables]
+  [./u]
+    scaling = 1e-5
+  [../]
+[]
+
+[Kernels]
+  [./diff]
+    type = CoefDiffusion
+    variable = u
+    coef = 0.1
+  [../]
+  [./time]
+    type = TimeDerivative
+    variable = u
+  [../]
+[]
+
+[BCs]
+  [./left]
+    type = DirichletBC
+    variable = u
+    preset = false
+    boundary = left
+    value = -1000
+  [../]
+  [./right]
+    type = DirichletBC
+    variable = u
+    preset = false
+    boundary = right
+    value = 100000
+  [../]
+[]
+
+[Executioner]
+  type = Transient
+  scheme = 'implicit-euler'
+  line_search = 'none'
+  solve_type = PJFNK
+
+  l_max_its = 20
+  nl_max_its = 20
+  nl_abs_div_tol = 1e+7
+  nl_div_tol = 1e+50
+  dt = 1
+  num_steps = 2
+
+  petsc_options = '-snes_converged_reason -ksp_converged_reason '
+  petsc_options_iname = '-pc_type -pc_hypre_type '
+  petsc_options_value = 'hypre boomeramg'
+[]
+
+[Outputs]
+  exodus = true
+[]

test/tests/executioners/nl_divergence_tolerance/tests

@@ -1,4 +1,4 @@
-[Tests]  
+[Tests]
   design = 'syntax/Executioner/index.md'
   [./test]
     type = 'Exodiff'
@@ -11,4 +11,12 @@
     requirement = "The Executioner system shall support the PETSc non-linear divergence tolerance."
     issues = '#13991'
   [../]
+  [./test_abs_divtol]
+    type = RunApp
+    input = 'nl_abs_divergence_tolerance.i'
+    expect_out = "Nonlinear solve did not converge due to DIVERGED_DTOL iterations 1"
+    requirement = 'The system shall consider a nonlinear solve diverged if the nonlinear residaul exceeds the absolute divergence tolerance while iterating'
+    issues = '#16474'
+    design = 'FEProblemSolve.md'
+  [../]
 []

test/tests/executioners/nl_forced_its/nl_forced_its.i

@@ -0,0 +1,64 @@
+[Mesh]
+  type = GeneratedMesh
+  dim = 2
+  nx = 15
+  ny = 15
+[]
+
+[Variables]
+  [./u]
+    scaling = 1e-5
+  [../]
+[]
+
+[Kernels]
+  [./diff]
+    type = CoefDiffusion
+    variable = u
+    coef = 0.1
+  [../]
+  [./time]
+    type = TimeDerivative
+    variable = u
+  [../]
+[]
+
+[BCs]
+  [./left]
+    type = DirichletBC
+    variable = u
+    preset = false
+    boundary = left
+    value = -1000
+  [../]
+  [./right]
+    type = DirichletBC
+    variable = u
+    preset = false
+    boundary = right
+    value = 100000
+  [../]
+[]
+
+[Executioner]
+  type = Transient
+  scheme = 'implicit-euler'
+  line_search = 'none'
+  solve_type = PJFNK
+
+  l_max_its = 20
+  nl_max_its = 20
+  nl_forced_its = 4
+  nl_abs_div_tol = 1e+5
+
+  dt = 1
+  num_steps = 2
+
+  petsc_options = '-snes_converged_reason -ksp_converged_reason '
+  petsc_options_iname = '-pc_type -pc_hypre_type '
+  petsc_options_value = 'hypre boomeramg'
+[]
+
+[Outputs]
+  exodus = true
+[]

test/tests/executioners/nl_forced_its/tests

@@ -0,0 +1,11 @@
+[Tests]
+  design = 'syntax/Executioner/index.md'
+  [./test_nl_forced_iterations]
+    type = RunApp
+    input = 'nl_forced_its.i'
+    expect_out = "Nonlinear solve did not converge due to DIVERGED_DTOL iterations 4"
+    requirement = 'The system shall perform n non linear iterations before checking for non linear divergence'
+    issues = '#16474'
+    design = 'FEProblemSolve.md'
+  [../]
+[]