Workflow after Eigenvalue run.

[Jeremyb8707bigbrain]

Hey yall my goal is to do a Transient starting at k_eff = 1 so I can study graphite thickness and how temperature pertubations back up my previous calculations for negative ITC's.

I have already ran an Eigenvalue (I also scaled power to match 1 MW) and got this CSV output.

time,bnorm,flux_g1,flux_g2,flux_g3,flux_g4,k_eff,powernorm,tot_fissions
0,490839.16863144,0,0,0,0,0,7.4322099599445e-08,2401.4969806237
1,7.8353817302008e+16,2.3563712864225e+18,7.0828794974811e+18,1.1799200733977e+19,4.3136887014398e+19,0.84007512019249,1000000,3.2315070456014e+16

My question was how do I continue to my goal, when I try to continue to the transient and scale my eigenvalue accordingly, it doesnt converge because of the new temperature fluctuations + time is incorporated.
I tried doing a Steady solve but it does not let me use any Time Kernels, though I saw in `moltres/problems/2021-cnrs-benchmark/phase-0/temperature.i' That time Kernels are seemingly used.

What is the best method to incorporate temperature and time without killing my convergence?

Current Steady-Transient Input File: I have this for now and I have all the kernels and behavior id like, its just getting it to converge with trying to set k_eff = 1 because I need that for a temperature pertubation. I dont care about power, just inlet temperature being 973K and it being at k_eff = 1

flow_velocity = 21.7

[GlobalParams]
    num_groups = 4
    num_precursor_groups = 6
    account_delayed = true
    sss2_input = true
    temperature = temp
    use_exp_form = false
    pre_concs = 'pre1 pre2 pre3 pre4 pre5 pre6'
    group_fluxes = 'g_1 g_2 g_3 g_4'
    eigenvalue_scaling = 0.84007512019249
[]

[Mesh]
    [initial_conditions]
        type = FileMeshGenerator
        file = 'research_eigen_exodus.e'
        use_for_exodus_restart = true
    []
[]

[Problem]
    type = FEProblem
    allow_initial_conditions_with_restart = true
[]

[Materials]
    [fuel_salt]
        type = MoltresJsonMaterial
        base_file = '../material_data/moltres_jsons/cluster_13cm.json'
        material_key = 'Molten_Salt'
        block = 'fuel_salt'
        interp_type = 'linear'
        prop_names = 'rho cp k'
        prop_values = '0.00194 2414 0.01'
    []
    [graphite]
        type = MoltresJsonMaterial
        base_file = '../material_data/moltres_jsons/cluster_13cm.json'
        material_key = 'Graphite'
        block = 'graphite'
        interp_type = 'linear'
        prop_names = 'rho cp k'
        prop_values = '0.00175 1820 0.45'
    []
[]

[Precursors]
  [delayed]
    var_name_base = 'pre'
    outlet_boundaries = '103'
    inlet_boundaries = '104'
    w_def = ${flow_velocity}
    v_def = 0
    u_def = 0
    block = 'fuel_salt'
    nt_exp_form = false
    family = MONOMIAL
    order = CONSTANT
    loop_precursors = false
    init_from_file = true
  []
[]

[Nt]
    var_name_base = g_
    pre_blocks = 'fuel_salt'
    create_temperature_var = false
    fission_blocks = 'fuel_salt'
    vacuum_boundaries = '10000 10001 10002'
    init_nts_from_file = true
[]

[Variables]
  [temp]
    family = LAGRANGE
    order = FIRST
    initial_condition = 973.0
  []
[]

[Kernels]
  [temp_time]
    type = MatINSTemperatureTimeDerivative
    variable = temp
  []
  [temp_source]
    type = TransientFissionHeatSource
    variable = temp
    block = 'fuel_salt'
  []
  [temp_advection]
    type = ConservativeTemperatureAdvection
    velocity_variable = '0 0 ${flow_velocity}'
    variable = temp
    block = 'fuel_salt'
  []
  [temp_conduction]
    type = MatDiffusion
    variable = temp
    diffusivity = 'k'
  []
  [temp_sink]
    type = ConvectiveHeatExchanger
    variable = temp
    htc = 1 
    tref = 973.0
  []
[]

[BCs]
  [inlet]
    type = TemperatureInflowBC
    boundary = '104'
    variable = temp
    inlet_conc = 973.0
    ww = ${flow_velocity}
  []
  [outlet]
      type = TemperatureOutflowBC
      boundary = '103'
      variable = temp
      velocity = '0 0 ${flow_velocity}'
  []
[]

[Preconditioning]
  [SMP]
    type = SMP
    full = true
  []
[]

[Executioner]
  type = Transient
  solve_type = 'PJFNK'
  petsc_options = '-snes_converged_reason -ksp_converged_reason -snes_linesearch_monitor'
  petsc_options_iname = '-pc_type -pc_hypre_type'
  petsc_options_value = 'hypre boomeramg'

  automatic_scaling = true
  compute_scaling_once = false
  resid_vs_jac_scaling_param = 0.1

  dtmin = 1e-6
  dtmax = 10.0
  end_time = 1000
  steady_state_detection = true
  [TimeStepper]
    type = IterationAdaptiveDT
    dt = 1e-5
    growth_factor = 1.4
    cutback_factor = 0.6
  []
[]

[Postprocessors]
  [power_norm]
    type = ElmIntegTotFissHeatPostprocessor
    execute_on = linear
  []
  [flux_g1]
    type = ElementIntegralVariablePostprocessor
    variable = g_1
  []
  [flux_g2]
    type = ElementIntegralVariablePostprocessor
    variable = g_2
  []
  [flux_g3]
    type = ElementIntegralVariablePostprocessor
    variable = g_3
  []
  [flux_g4]
    type = ElementIntegralVariablePostprocessor
    variable = g_4
  []
  [fuel_temp]
    type = ElementAverageValue
    variable = temp
    block = 'fuel_salt'
  []
  [graphite_temp]
    type = ElementAverageValue
    variable = temp
    block = 'graphite'
  []
  [inlet_temp]
    type = SideAverageValue
    variable = temp
    boundary = '104'
  []
  [outlet_temp]
    type = SideAverageValue
    variable = temp
    boundary = '103'
  []
  [bnorm]
    type = ElmIntegTotFissNtsPostprocessor
    block = 'fuel_salt'
    execute_on = linear
  []
  [tot_fissions]
    type = ElmIntegTotFissPostprocessor
    execute_on = linear
  []
[]

[Outputs]
    perf_graph = true
    [exodus]
      type = Exodus
      execute_on = 'final'
    []
    [csv]
      type = CSV
      execute_on = 'final'
    []
[]

[Jeremyb8707bigbrain]

I was thinking maybe MultiApp to help with the convergence a bit 1 app for neutronics another for loose temperature stuff maybe

[Jeremyb8707bigbrain]

Multiapp solved all my issues lol fantastic