remove solve_background_neutrals flag

docs/src/config.md

@@ -40,8 +40,7 @@ Aside from these arguments, all others have  default values provided. These are
 - `source_electron_energy`: Extra source term for electron energy equation. Defaults to `Returns(0.0)`. See [User-Provided Source Terms](@ref) for more information.
 - `LANDMARK`: Whether we are using the LANDMARK physics model. This affects whether certain terms are included in the equations, such as electron and heavy species momentum transfer due to ionization and the form of the electron thermal conductivity. Also affects whether we use an anode sheath model. Defaults to `false`.
 - `ion_wall_losses`: Whether we model ion losses to the walls. Defaults to `false`.
-- `solve_background_neutrals`: Turns on an additional mass flow rate due to neutral ingestion
-- `background_pressure`: The pressure of the background neutrals, in Pascals
+- `background_pressure`: The pressure of the background neutrals, in Pascals. These background neutrals are injected at the anode to simulate the ingestion of facility neutrals.
 - `background_neutral_temperature`: The temperature of the background neutrals, in K
 - `anode_boundary_condition`: Can be either `:sheath` or `:dirichlet`
 - `anom_smoothing_iters`: How many times to smooth the anomalous transport profile

src/simulation/boundaryconditions.jl

@@ -29,9 +29,7 @@ function left_boundary_state!(bc_state, U, params)
     bc_state[index.ρn] = mdot_a / channel_area[1] / un
 
     # Add ingested mass flow rate at anode
-    if config.solve_background_neutrals
-        bc_state[index.ρn] += params.background_neutral_density * params.background_neutral_velocity / un
-    end
+    bc_state[index.ρn] += params.background_neutral_density * params.background_neutral_velocity / un
 
     @inbounds for Z in 1:params.config.ncharge
         interior_density = U[index.ρi[Z],   begin+1]

src/simulation/configuration.jl

@@ -41,7 +41,6 @@ struct Config{A<:AnomalousTransportModel, TC<:ThermalConductivityModel, W<:WallL
     LANDMARK::Bool
     anode_mass_flow_rate::Float64
     ion_wall_losses::Bool
-    solve_background_neutrals::Bool
     background_pressure::Float64
     background_neutral_temperature::Float64
     anode_boundary_condition::Symbol
@@ -85,7 +84,6 @@ function Config(;
         scheme::HyperbolicScheme            = HyperbolicScheme(),
         LANDMARK                            = false,
         ion_wall_losses                     = false,
-        solve_background_neutrals           = false,
         background_pressure                 = 0.0u"Torr",
         background_neutral_temperature      = 100.0u"K",
         anode_boundary_condition            = :sheath,
@@ -146,7 +144,6 @@ function Config(;
         LANDMARK,
         anode_mass_flow_rate,
         ion_wall_losses,
-        solve_background_neutrals,
         background_pressure,
         background_neutral_temperature,
         anode_boundary_condition,

src/simulation/simulation.jl

@@ -132,11 +132,6 @@ function run_simulation(
         error("LANDMARK configuration needs to use the LANDMARK thermal conductivity model.")
     end
 
-    #check that user is aware of neutral backflow flag
-    if (config.background_pressure > 0.0) && (config.solve_background_neutrals == false)
-        @warn("Background neutral pressure set but solve background neutrals not enabled. Did you mean to set solve_background_neutrals to true?")
-    end
-
     # If duration and/or dt are provided with units, convert to seconds and then strip units
     duration = convert_to_float64(duration, u"s")
     dt = convert_to_float64(dt, u"s")
@@ -291,7 +286,7 @@ function run_simulation(json_content::JSON3.Object; single_section = false, nons
                 anom_model, cathode_location_m, max_charge,
                 num_cells, dt_s, duration_s, num_save,
                 flux_function, limiter, reconstruct,
-                ion_wall_losses, electron_ion_collisions, solve_background_neutrals,
+                ion_wall_losses, electron_ion_collisions,
                 # Parameters
                 sheath_loss_coefficient,
                 ion_temp_K, neutral_temp_K, neutral_velocity_m_s,
@@ -313,7 +308,7 @@ function run_simulation(json_content::JSON3.Object; single_section = false, nons
                 anom_model, cathode_location_m, max_charge,
                 num_cells, dt_s, duration_s, num_save,
                 flux_function, limiter, reconstruct,
-                ion_wall_losses, electron_ion_collisions, solve_background_neutrals,
+                ion_wall_losses, electron_ion_collisions,
                 # Parameters
                 sheath_loss_coefficient,
                 ion_temp_K, neutral_temp_K, neutral_velocity_m_s,
@@ -358,7 +353,7 @@ function run_simulation(json_content::JSON3.Object; single_section = false, nons
             anom_model, cathode_location_m, max_charge,
             num_cells, dt_s, duration_s, num_save,
             flux_function, limiter, reconstruct,
-            ion_wall_losses, electron_ion_collisions, solve_background_neutrals,
+            ion_wall_losses, electron_ion_collisions,
         ) = simulation
 
         (;
@@ -444,7 +439,6 @@ function run_simulation(json_content::JSON3.Object; single_section = false, nons
         scheme = HyperbolicScheme(;
             flux_function = eval(Symbol(flux_function)), limiter = eval(Symbol(limiter)), reconstruct
         ),
-        solve_background_neutrals = solve_background_neutrals,
         background_pressure = background_pressure_Torr * u"Torr",
         background_neutral_temperature = background_temperature_K * u"K",
         apply_thrust_divergence_correction

test/order_verification/ovs_energy.jl

@@ -118,7 +118,7 @@ function verify_energy(ncells; niters = 20000)
         ncharge = 1, source_energy = source_func, implicit_energy = 1.0,
         min_electron_temperature, transition_function, LANDMARK, propellant,
         ionization_model, excitation_model, wall_loss_model, geometry,
-        anode_boundary_condition = :dirichlet, solve_background_neutrals = false,
+        anode_boundary_condition = :dirichlet,
         conductivity_model = HallThruster.LANDMARK_conductivity(),
     )
 
@@ -165,7 +165,7 @@ function verify_energy(ncells; niters = 20000)
         ncharge = 1, source_energy = source_func, implicit_energy = 0.5,
         min_electron_temperature, transition_function, LANDMARK, propellant,
         ionization_model, excitation_model, wall_loss_model, geometry,
-        anode_boundary_condition = :dirichlet, solve_background_neutrals = false,
+        anode_boundary_condition = :dirichlet,
         conductivity_model = HallThruster.LANDMARK_conductivity(),
     )
 

test/order_verification/ovs_ions.jl

@@ -94,7 +94,6 @@ function solve_ions(ncells, scheme; t_end = 1e-4)
         conductivity_model = HallThruster.LANDMARK_conductivity(),
         ion_wall_losses = false,
         anode_boundary_condition = :dirichlet,
-        solve_background_neutrals = false,
     )
 
     z_edge = grid.edges

test/unit_tests/input_shifted.json

@@ -42,7 +42,6 @@
         "ion_wall_losses": true,
         "electron_ion_collisions": true,
         "anom_model": "ShiftedTwoZone",
-        "solve_background_neutrals": true,
         "adaptive": true
     }
 }

test/unit_tests/input_twozone.json

@@ -38,7 +38,6 @@
         "ion_wall_losses": true,
         "electron_ion_collisions": true,
         "anom_model": "TwoZoneBohm",
-        "solve_background_neutrals": true,
         "adaptive": true
     }
 }

test/unit_tests/test_boundary_conditions.jl

@@ -13,7 +13,6 @@
         LANDMARK = true,
         conductivity_model = HallThruster.LANDMARK_conductivity(),
         anode_boundary_condition = :dirichlet,
-        solve_background_neutrals = :true,
         neutral_temperature = 300.0,
         ion_temperature = 300.0,
         background_pressure = 6e-4,

test/unit_tests/test_initialization.jl

@@ -103,7 +103,6 @@ end
     )
 
     config = HallThruster.Config(;
-        solve_background_neutrals = false,
         background_pressure = 0.0u"Torr",
         background_neutral_temperature = 0.0u"K",
         common_opts...
@@ -149,7 +148,6 @@ end
     TB = 120u"K"
 
     config_bg = HallThruster.Config(;
-        solve_background_neutrals = true,
         background_pressure = pB,
         background_neutral_temperature = TB,
         common_opts...

test/unit_tests/test_json.jl

@@ -15,7 +15,6 @@
     @test config.thruster.name == "SPT-100"
     @test config.propellant == Xenon
     @test config.anode_mass_flow_rate ≈ 3e-6
-    @test config.solve_background_neutrals == true
     @test config.ion_wall_losses == true
     @test sol.params.adaptive == true
 
@@ -25,4 +24,4 @@
     @test config.anom_model isa HallThruster.TwoZoneBohm
     @test config.anom_model.coeffs[1] ≈ 1/160
     @test config.anom_model.coeffs[2] ≈ 1/16
-end
+end

test/unit_tests/test_misc.jl

@@ -17,17 +17,6 @@
     )
 
     @test_logs (:warn, "CFL for adaptive timestepping set higher than stability limit of 0.8. Setting CFL to 0.799.") HallThruster.run_simulation(config; dt=5e-9, duration=0e-9, grid = HallThruster.EvenGrid(2), nsave = 10, adaptive = true, CFL = 0.9)
-
-    pressure_config = HallThruster.Config(;
-        thruster = HallThruster.SPT_100,
-        domain = (0.0u"cm", 8.0u"cm"),
-        discharge_voltage = 300.0u"V",
-        anode_mass_flow_rate = 5u"mg/s",
-        background_pressure = 1.0u"Pa",
-    )
-
-    @test_logs (:warn, "Background neutral pressure set but solve background neutrals not enabled. Did you mean to set solve_background_neutrals to true?") HallThruster.run_simulation(pressure_config; dt=5e-9, duration=4e-9, grid = HallThruster.EvenGrid(2), nsave = 10)
-
 end
 
 @testset "Linear algebra" begin