add first implementation of the ml-swe in 1D

examples/tree_1d_dgsem/elixir_shallowwater_multilayer_convergence.jl

@@ -0,0 +1,60 @@
+
+using OrdinaryDiffEq
+using Trixi
+using TrixiShallowWater
+
+###############################################################################
+# Semidiscretization of the two-layer shallow water equations
+
+equations = ShallowWaterMultiLayerEquations1D(gravity_constant = 10.0, rhos = (0.9, 1.0))
+
+initial_condition = initial_condition_convergence_test
+
+###############################################################################
+# Get the DG approximation space
+
+volume_flux = (flux_ersing_etal, flux_nonconservative_ersing_etal)
+solver = DGSEM(polydeg = 3,
+               surface_flux = (flux_ersing_etal, flux_nonconservative_ersing_etal),
+               volume_integral = VolumeIntegralFluxDifferencing(volume_flux))
+
+###############################################################################
+# Get the TreeMesh and setup a periodic mesh
+
+coordinates_min = 0.0
+coordinates_max = sqrt(2.0)
+mesh = TreeMesh(coordinates_min, coordinates_max,
+                initial_refinement_level = 3,
+                n_cells_max = 10_000,
+                periodicity = true)
+
+# create the semi discretization object
+semi = SemidiscretizationHyperbolic(mesh, equations, initial_condition, solver,
+                                    source_terms = source_terms_convergence_test)
+
+###############################################################################
+# ODE solvers, callbacks etc.
+
+tspan = (0.0, 1.0)
+ode = semidiscretize(semi, tspan)
+
+summary_callback = SummaryCallback()
+
+analysis_interval = 500
+analysis_callback = AnalysisCallback(semi, interval = analysis_interval)
+
+alive_callback = AliveCallback(analysis_interval = analysis_interval)
+
+save_solution = SaveSolutionCallback(interval = 500,
+                                     save_initial_solution = true,
+                                     save_final_solution = true)
+
+callbacks = CallbackSet(summary_callback, analysis_callback, alive_callback, save_solution)
+
+###############################################################################
+# run the simulation
+
+# use a Runge-Kutta method with automatic (error based) time step size control
+sol = solve(ode, RDPK3SpFSAL49(), abstol = 1.0e-8, reltol = 1.0e-8,
+            save_everystep = false, callback = callbacks);
+summary_callback() # print the timer summary

src/TrixiShallowWater.jl

@@ -8,7 +8,7 @@ using Trixi
 # Import additional symbols that are not exported by Trixi.jl
 using Trixi: get_node_vars, set_node_vars!, waterheight
 using MuladdMacro: @muladd
-using StaticArrays: SVector, @SMatrix
+using StaticArrays: SVector, @SMatrix, MVector
 using Static: True, False
 using LinearAlgebra: norm
 
@@ -19,15 +19,17 @@ include("solvers/indicators.jl")
 
 # Export types/functions that define the public API of TrixiShallowWater.jl
 export ShallowWaterEquationsWetDry1D, ShallowWaterEquationsWetDry2D,
-       ShallowWaterTwoLayerEquations1D, ShallowWaterTwoLayerEquations2D
+       ShallowWaterTwoLayerEquations1D, ShallowWaterTwoLayerEquations2D,
+       ShallowWaterMultiLayerEquations1D
 
 export hydrostatic_reconstruction_chen_noelle, flux_nonconservative_chen_noelle,
-       min_max_speed_chen_noelle,
-       flux_hll_chen_noelle
+       min_max_speed_chen_noelle, flux_hll_chen_noelle,
+       flux_ersing_etal, flux_es_ersing_etal
 
-export flux_es_ersing_etal
+export nlayers, eachlayer
 
 export PositivityPreservingLimiterShallowWater
+
 export IndicatorHennemannGassnerShallowWater
 
 end

src/equations/equations.jl

@@ -13,4 +13,32 @@ include("shallow_water_wet_dry_2d.jl")
 
 include("shallow_water_two_layer_1d.jl")
 include("shallow_water_two_layer_2d.jl")
+
+abstract type AbstractShallowWaterMultiLayerEquations{NDIMS, NVARS, NLAYERS} <:
+              Trixi.AbstractEquations{NDIMS, NVARS} end
+include("shallow_water_multilayer_1d.jl")
+
+"""
+    eachlayer(equations::AbstractShallowWaterMultiLayerEquations)
+
+Return an iterator over the indices that specify the location in relevant data structures
+for the layers in `AbstractShallowWaterMultiLayerEquations`.
+"""
+@inline function eachlayer(equations::AbstractShallowWaterMultiLayerEquations)
+    Base.OneTo(nlayers(equations))
+end
+
+"""
+    nlayers(equations::AbstractShallowWaterMultiLayerEquations)
+
+Retrieve the number of layers from an equation instance of the `AbstractShallowWaterMultiLayerEquations`.
+"""
+@inline function nlayers(::AbstractShallowWaterMultiLayerEquations{NDIMS, NVARS,
+                                                                   NLAYERS}) where {
+                                                                                    NDIMS,
+                                                                                    NVARS,
+                                                                                    NLAYERS
+                                                                                    }
+    NLAYERS
+end
 end # @muladd