diff --git a/src/surface_heating.jl b/src/surface_heating.jl
index d58ea32..86e8d59 100644
--- a/src/surface_heating.jl
+++ b/src/surface_heating.jl
@@ -119,10 +119,10 @@ julia> using Walrus
 julia> using Oceananigans
 
 julia> wind_stress = WindStress(; reference_wind_speed = 0., reference_wind_direction = 90.)
-(::WindStress{Walrus.ReturnValue{Float64}, Walrus.ReturnValue{Float64}, LogarithmicNeutralWind{Float64, Nothing}, Float64}) (generic function with 2 methods)
+(::WindStress{Float64, Float64, LogarithmicNeutralWind{Float64, Nothing}, Float64}) (generic function with 2 methods)
 
 julia> surface_heat_exchange = SurfaceHeatExchange(; wind_stress)
-(::SurfaceHeatExchange{WindStress{Walrus.ReturnValue{Float64}, Walrus.ReturnValue{Float64}, LogarithmicNeutralWind{Float64, Nothing}, Float64}, Walrus.ReturnValue{Int64}, Walrus.SurfaceHeatingModel.EmpiricalLatentHeatVaporisation{Float64}, Walrus.SurfaceHeatingModel.AugustRocheMagnusVapourPressure{Float64}, Float64}) (generic function with 1 method)
+(::SurfaceHeatExchange{WindStress{Float64, Float64, LogarithmicNeutralWind{Float64, Nothing}, Float64}, Int64, Walrus.SurfaceHeatingModel.EmpiricalLatentHeatVaporisation{Float64}, Walrus.SurfaceHeatingModel.AugustRocheMagnusVapourPressure{Float64}, Float64}) (generic function with 1 method)
 
 julia> boundary_conditions = (; T = FieldBoundaryConditions(top = FluxBoundaryCondition(surface_heat_exchange, field_dependencies = (:T, :u, :v))))
 (T = Oceananigans.FieldBoundaryConditions, with boundary conditions
@@ -131,7 +131,7 @@ julia> boundary_conditions = (; T = FieldBoundaryConditions(top = FluxBoundaryCo
 ├── south: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
 ├── north: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
 ├── bottom: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
-├── top: FluxBoundaryCondition: ContinuousBoundaryFunction (::SurfaceHeatExchange{WindStress{Walrus.ReturnValue{Float64}, Walrus.ReturnValue{Float64}, LogarithmicNeutralWind{Float64, Nothing}, Float64}, Walrus.ReturnValue{Int64}, Walrus.SurfaceHeatingModel.EmpiricalLatentHeatVaporisation{Float64}, Walrus.SurfaceHeatingModel.AugustRocheMagnusVapourPressure{Float64}, Float64}) at (Nothing, Nothing, Nothing)
+├── top: FluxBoundaryCondition: ContinuousBoundaryFunction (::SurfaceHeatExchange{WindStress{Float64, Float64, LogarithmicNeutralWind{Float64, Nothing}, Float64}, Int64, Walrus.SurfaceHeatingModel.EmpiricalLatentHeatVaporisation{Float64}, Walrus.SurfaceHeatingModel.AugustRocheMagnusVapourPressure{Float64}, Float64}) at (Nothing, Nothing, Nothing)
 └── immersed: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing),)
 
 ```
@@ -190,10 +190,10 @@ Example
 julia> using Walrus
 
 julia> wind_stress = WindStress(; reference_wind_speed = 0., reference_wind_direction = 90.)
-(::WindStress{Walrus.ReturnValue{Float64}, Walrus.ReturnValue{Float64}, LogarithmicNeutralWind{Float64, Nothing}, Float64}) (generic function with 2 methods)
+(::WindStress{Float64, Float64, LogarithmicNeutralWind{Float64, Nothing}, Float64}) (generic function with 2 methods)
 
 julia> surface_heat_exchange = SurfaceHeatExchangeBoundaryCondition(; wind_stress)
-FluxBoundaryCondition: ContinuousBoundaryFunction (::SurfaceHeatExchange{WindStress{Walrus.ReturnValue{Float64}, Walrus.ReturnValue{Float64}, LogarithmicNeutralWind{Float64, Nothing}, Float64}, Walrus.ReturnValue{Int64}, Walrus.SurfaceHeatingModel.EmpiricalLatentHeatVaporisation{Float64}, Walrus.SurfaceHeatingModel.AugustRocheMagnusVapourPressure{Float64}, Float64}) at (Nothing, Nothing, Nothing)
+FluxBoundaryCondition: DiscreteBoundaryFunction with (::SurfaceHeatExchange{WindStress{Float64, Float64, LogarithmicNeutralWind{Float64, Nothing}, Float64}, Int64, Walrus.SurfaceHeatingModel.EmpiricalLatentHeatVaporisation{Float64}, Walrus.SurfaceHeatingModel.AugustRocheMagnusVapourPressure{Float64}, Float64})
 
 ```
 """
diff --git a/src/wind_stress.jl b/src/wind_stress.jl
index fb534cd..f440d8c 100644
--- a/src/wind_stress.jl
+++ b/src/wind_stress.jl
@@ -74,7 +74,7 @@ julia> reference_wind_direction = 0.
 0.0
 
 julia> wind_stress = WindStress(; reference_wind_speed, reference_wind_direction)
-(::WindStress{Walrus.ReturnValue{Float64}, Walrus.ReturnValue{Float64}, LogarithmicNeutralWind{Float64, Nothing}, Float64}) (generic function with 2 methods)
+(::WindStress{Float64, Float64, LogarithmicNeutralWind{Float64, Nothing}, Float64}) (generic function with 2 methods)
 
 julia> boundary_conditions = (u = FieldBoundaryConditions(top = FluxBoundaryCondition(wind_stress, parameters = Val(:x))),
                               v = FieldBoundaryConditions(top = FluxBoundaryCondition(wind_stress, parameters = Val(:y))))
@@ -84,14 +84,14 @@ julia> boundary_conditions = (u = FieldBoundaryConditions(top = FluxBoundaryCond
 ├── south: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
 ├── north: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
 ├── bottom: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
-├── top: FluxBoundaryCondition: ContinuousBoundaryFunction (::WindStress{Walrus.ReturnValue{Float64}, Walrus.ReturnValue{Float64}, LogarithmicNeutralWind{Float64, Nothing}, Float64}) at (Nothing, Nothing, Nothing)
+├── top: FluxBoundaryCondition: ContinuousBoundaryFunction (::WindStress{Float64, Float64, LogarithmicNeutralWind{Float64, Nothing}, Float64}) at (Nothing, Nothing, Nothing)
 └── immersed: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing), v = Oceananigans.FieldBoundaryConditions, with boundary conditions
 ├── west: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
 ├── east: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
 ├── south: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
 ├── north: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
 ├── bottom: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
-├── top: FluxBoundaryCondition: ContinuousBoundaryFunction (::WindStress{Walrus.ReturnValue{Float64}, Walrus.ReturnValue{Float64}, LogarithmicNeutralWind{Float64, Nothing}, Float64}) at (Nothing, Nothing, Nothing)
+├── top: FluxBoundaryCondition: ContinuousBoundaryFunction (::WindStress{Float64, Float64, LogarithmicNeutralWind{Float64, Nothing}, Float64}) at (Nothing, Nothing, Nothing)
 └── immersed: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing))
 
 ```
@@ -137,7 +137,7 @@ julia> using Walrus: WindStressBoundaryConditions
 julia> using Oceananigans
 
 julia> wind_stress_boundary_conditions = WindStressBoundaryConditions(; reference_wind_speed = 0.1, reference_wind_direction = 90.)
-(u = FluxBoundaryCondition: ContinuousBoundaryFunction (::WindStress{Walrus.ReturnValue{Float64}, Walrus.ReturnValue{Float64}, LogarithmicNeutralWind{Float64, Nothing}, Float64}) at (Nothing, Nothing, Nothing), v = FluxBoundaryCondition: ContinuousBoundaryFunction (::WindStress{Walrus.ReturnValue{Float64}, Walrus.ReturnValue{Float64}, LogarithmicNeutralWind{Float64, Nothing}, Float64}) at (Nothing, Nothing, Nothing))
+(u = FluxBoundaryCondition: DiscreteBoundaryFunction (::WindStress{Float64, Float64, LogarithmicNeutralWind{Float64, Nothing}, Float64}) with parameters Val{:x}, v = FluxBoundaryCondition: DiscreteBoundaryFunction (::WindStress{Float64, Float64, LogarithmicNeutralWind{Float64, Nothing}, Float64}) with parameters Val{:y})
 
 julia> boundary_conditions = (u = FieldBoundaryConditions(top = wind_stress_boundary_conditions.u),
                               v = FieldBoundaryConditions(top = wind_stress_boundary_conditions.v))
@@ -147,14 +147,14 @@ julia> boundary_conditions = (u = FieldBoundaryConditions(top = wind_stress_boun
 ├── south: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
 ├── north: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
 ├── bottom: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
-├── top: FluxBoundaryCondition: ContinuousBoundaryFunction (::WindStress{Walrus.ReturnValue{Float64}, Walrus.ReturnValue{Float64}, LogarithmicNeutralWind{Float64, Nothing}, Float64}) at (Nothing, Nothing, Nothing)
+├── top: FluxBoundaryCondition: DiscreteBoundaryFunction (::WindStress{Float64, Float64, LogarithmicNeutralWind{Float64, Nothing}, Float64}) with parameters Val{:x}
 └── immersed: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing), v = Oceananigans.FieldBoundaryConditions, with boundary conditions
 ├── west: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
 ├── east: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
 ├── south: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
 ├── north: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
 ├── bottom: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing)
-├── top: FluxBoundaryCondition: ContinuousBoundaryFunction (::WindStress{Walrus.ReturnValue{Float64}, Walrus.ReturnValue{Float64}, LogarithmicNeutralWind{Float64, Nothing}, Float64}) at (Nothing, Nothing, Nothing)
+├── top: FluxBoundaryCondition: DiscreteBoundaryFunction (::WindStress{Float64, Float64, LogarithmicNeutralWind{Float64, Nothing}, Float64}) with parameters Val{:y}
 └── immersed: DefaultBoundaryCondition (FluxBoundaryCondition: Nothing))
 
 ```