added error warning to KdV (#232)

* added error warning to KdV

* define check_solver

* clean up

* format

* Update src/semidiscretization.jl

Co-authored-by: Collin Wittenstein <126870995+cwittens@users.noreply.github.com>

---------

Co-authored-by: Joshua Lampert <joshua.lampert@uni-hamburg.de>
Co-authored-by: Joshua Lampert <51029046+JoshuaLampert@users.noreply.github.com>

Author: cwittens

src/equations/bbm_1d.jl

@@ -53,6 +53,12 @@ function BBMEquation1D(; gravity, D = 1.0, eta0 = 0.0, split_form = true)
     BBMEquation1D(gravity, D, eta0, split_form)
 end
 
+function check_solver(::BBMEquation1D, solver, boundary_conditions)
+    if isnothing(solver.D2)
+        throw(ArgumentError("The BBM equation requires a second-derivative operator. Explicitly set `D2`."))
+    end
+end
+
 """
     initial_condition_convergence_test(x, t, equations::BBMEquation1D, mesh)
 

src/equations/bbm_bbm_1d.jl

@@ -64,6 +64,12 @@ function BBMBBMEquations1D(; bathymetry_type = bathymetry_variable,
     BBMBBMEquations1D(bathymetry_type, gravity, eta0)
 end
 
+function check_solver(::BBMBBMEquations1D, solver, boundary_conditions)
+    if isnothing(solver.D2)
+        throw(ArgumentError("The BBM-BBM equations require a second-derivative operator. Explicitly set `D2`."))
+    end
+end
+
 """
     initial_condition_convergence_test(x, t, equations::BBMBBMEquations1D, mesh)
 

src/equations/kdv_1d.jl

@@ -53,6 +53,13 @@ function KdVEquation1D(; gravity, D = 1.0, eta0 = 0.0)
     KdVEquation1D(gravity, D, eta0)
 end
 
+function check_solver(::KdVEquation1D, solver, boundary_conditions)
+    if !(solver.D1 isa PeriodicUpwindOperators && isnothing(solver.D3)) &&
+       isnothing(solver.D3)
+        throw(ArgumentError("The KdV equation requires a third-derivative operator. Either explicitly set `D3` or set `D1` as an upwind operator."))
+    end
+end
+
 """
     initial_condition_soliton(x, t, equations::KdVEquation1D, mesh)
 
@@ -133,14 +140,14 @@ where `D` is the still-water depth.
 
 !!! warning "Parameter constraints"
     This conversion is only valid for equations with specific parameter values:
-    - `gravity = 4/27` 
-    - `D = 3.0` 
-    
-    These values ensure the dimensional KdV equation matches the standard 
+    - `gravity = 4/27`
+    - `D = 3.0`
+
+    These values ensure the dimensional KdV equation matches the standard
     non-dimensional form `u_t + u u_x + u_{xxx} = 0`.
 
-This function allows converting solutions from the standard non-dimensional 
-KdV form commonly found in literature to the dimensional form implemented 
+This function allows converting solutions from the standard non-dimensional
+KdV form commonly found in literature to the dimensional form implemented
 in DispersiveShallowWater.jl.
 
 See also [`prim2nondim`](@ref).
@@ -153,7 +160,7 @@ end
 """
     prim2nondim(eta, equations::KdVEquation1D)
 
-Convert the primitive/physical variable `eta` (total water height) to the 
+Convert the primitive/physical variable `eta` (total water height) to the
 non-dimensional variable `u` for the [`KdVEquation1D`](@ref).
 
 The transformation is given by:
@@ -164,15 +171,15 @@ where `D` is the still-water depth.
 
 !!! warning "Parameter constraints"
     This conversion is only valid for equations with specific parameter values:
-    - `gravity = 4/27` 
+    - `gravity = 4/27`
     - `D = 3.0`
-    
-    These values ensure the dimensional KdV equation matches the standard 
+
+    These values ensure the dimensional KdV equation matches the standard
     non-dimensional form `u_t + u u_x + u_{xxx} = 0`.
 
-This function allows converting solutions from the dimensional form implemented 
-in DispersiveShallowWater.jl to the standard non-dimensional KdV form 
-commonly found in literature, enabling comparison with theoretical results 
+This function allows converting solutions from the dimensional form implemented
+in DispersiveShallowWater.jl to the standard non-dimensional KdV form
+commonly found in literature, enabling comparison with theoretical results
 and other implementations.
 
 See also [`nondim2prim`](@ref).

src/equations/svaerd_kalisch_1d.jl

@@ -68,6 +68,12 @@ function SvaerdKalischEquations1D(; bathymetry_type = bathymetry_variable, gravi
     SvaerdKalischEquations1D(bathymetry_type, gravity, eta0, alpha, beta, gamma)
 end
 
+function check_solver(::SvaerdKalischEquations1D, solver, ::BoundaryConditionPeriodic)
+    if isnothing(solver.D2)
+        throw(ArgumentError("The Svärd-Kalisch equations with periodic boundary conditions require a second-derivative operator. Explicitly set `D2`."))
+    end
+end
+
 """
     initial_condition_manufactured(x, t, equations::SvaerdKalischEquations1D, mesh)
 

src/semidiscretization.jl

@@ -76,6 +76,7 @@ function Semidiscretization(mesh, equations, initial_condition, solver;
         throw(ArgumentError("Non-periodic derivative operators in `solver` are incompatible with periodic boundary conditions."))
     end
 
+    check_solver(equations, solver, boundary_conditions)
     cache = (;
              create_cache(mesh, equations, solver, initial_condition, boundary_conditions,
                           RealT, uEltype)...,
@@ -88,6 +89,19 @@ function Semidiscretization(mesh, equations, initial_condition, solver;
                                                       solver, cache)
 end
 
+"""
+    check_solver(equations, solver, boundary_conditions)
+
+Check that the `solver` is compatible with the given `equations` and 
+`boundary_conditions`. The default implementation performs no checks.
+Specific equation types can override this method to validate that 
+required derivative operators are present (e.g., some equations 
+require `D2` or `D3` to be non-`nothing`).
+
+Throws an `ArgumentError` if the solver is incompatible.
+"""
+check_solver(equations, solver, boundary_conditions) = nothing
+
 function Base.show(io::IO, semi::Semidiscretization)
     @nospecialize semi # reduce precompilation time
 

test/test_unit.jl

@@ -92,6 +92,29 @@ end
     @test_throws ArgumentError semidiscretize(semi_flat, (0.0, 1.0))
 end
 
+@testitem "Solver consistency" setup=[Setup, AdditionalImports] begin
+    mesh = Mesh1D(-1.0, 1.0, 10)
+    initial_condition = initial_condition_convergence_test
+    D1 = periodic_derivative_operator(1, 4, mesh.xmin, mesh.xmax, mesh.N)
+    solver = Solver(D1)
+
+    equations = KdVEquation1D(gravity = 1.0)
+    @test_throws ArgumentError Semidiscretization(mesh, equations, initial_condition,
+                                                  solver)
+
+    equations = BBMEquation1D(gravity = 1.0)
+    @test_throws ArgumentError Semidiscretization(mesh, equations, initial_condition,
+                                                  solver)
+
+    equations = BBMBBMEquations1D(gravity = 1.0)
+    @test_throws ArgumentError Semidiscretization(mesh, equations, initial_condition,
+                                                  solver)
+
+    equations = SvaerdKalischEquations1D(gravity = 1.0)
+    @test_throws ArgumentError Semidiscretization(mesh, equations, initial_condition,
+                                                  solver)
+end
+
 @testitem "Boundary conditions" setup=[Setup] begin
     boundary_conditions = boundary_condition_periodic
     @test_nowarn print(boundary_conditions)