Viscous CFL 2D 3D TreeMesh

examples/tree_2d_dgsem/elixir_navierstokes_viscous_shock.jl

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+using OrdinaryDiffEqLowStorageRK
+using Trixi
+
+# This is the classic 1D viscous shock wave problem with analytical solution
+# for a special value of the Prandtl number.
+# The original references are:
+#
+# - R. Becker (1922)
+#   Stoßwelle und Detonation.
+#   [DOI: 10.1007/BF01329605](https://doi.org/10.1007/BF01329605)
+#
+#   English translations:
+#   Impact waves and detonation. Part I.
+#   https://ntrs.nasa.gov/api/citations/19930090862/downloads/19930090862.pdf
+#   Impact waves and detonation. Part II.
+#   https://ntrs.nasa.gov/api/citations/19930090863/downloads/19930090863.pdf
+#
+# - M. Morduchow, P. A. Libby (1949)
+#   On a Complete Solution of the One-Dimensional Flow Equations
+#   of a Viscous, Head-Conducting, Compressible Gas
+#   [DOI: 10.2514/8.11882](https://doi.org/10.2514/8.11882)
+#
+#
+# The particular problem considered here is described in
+# - L. G. Margolin, J. M. Reisner, P. M. Jordan (2017)
+#   Entropy in self-similar shock profiles
+#   [DOI: 10.1016/j.ijnonlinmec.2017.07.003](https://doi.org/10.1016/j.ijnonlinmec.2017.07.003)
+
+### Fixed parameters ###
+
+# Special value for which nonlinear solver can be omitted
+# Corresponds essentially to fixing the Mach number
+alpha = 0.5
+# We want kappa = cp * mu = mu_bar to ensure constant enthalpy
+prandtl_number() = 3 / 4
+
+### Free choices: ###
+gamma() = 5 / 3
+
+# In Margolin et al., the Navier-Stokes equations are given for an
+# isotropic stress tensor τ, i.e., ∇ ⋅ τ = μ Δu
+mu_isotropic() = 0.15
+mu_bar() = mu_isotropic() / (gamma() - 1) # Re-scaled viscosity
+
+rho_0() = 1
+v() = 1 # Shock speed
+
+domain_length = 4.0
+
+### Derived quantities ###
+
+Ma() = 2 / sqrt(3 - gamma()) # Mach number for alpha = 0.5
+c_0() = v() / Ma() # Speed of sound ahead of the shock
+
+# From constant enthalpy condition
+p_0() = c_0()^2 * rho_0() / gamma()
+
+l() = mu_bar() / (rho_0() * v()) * 2 * gamma() / (gamma() + 1) # Appropriate length scale
+
+"""
+    initial_condition_viscous_shock(x, t, equations)
+
+Classic 1D viscous shock wave problem with analytical solution
+for a special value of the Prandtl number.
+The version implemented here is described in
+- L. G. Margolin, J. M. Reisner, P. M. Jordan (2017)
+  Entropy in self-similar shock profiles
+  [DOI: 10.1016/j.ijnonlinmec.2017.07.003](https://doi.org/10.1016/j.ijnonlinmec.2017.07.003)
+"""
+function initial_condition_viscous_shock(x, t, equations)
+    y = x[1] - v() * t # Translated coordinate
+
+    # Coordinate transformation. See eq. (33) in Margolin et al. (2017)
+    chi = 2 * exp(y / (2 * l()))
+
+    w = 1 + 1 / (2 * chi^2) * (1 - sqrt(1 + 2 * chi^2))
+
+    rho = rho_0() / w
+    u = v() * (1 - w)
+    p = p_0() * 1 / w * (1 + (gamma() - 1) / 2 * Ma()^2 * (1 - w^2))
+
+    return prim2cons(SVector(rho, u, 0, p), equations)
+end
+initial_condition = initial_condition_viscous_shock
+
+###############################################################################
+# semidiscretization of the ideal compressible Navier-Stokes equations
+
+equations = CompressibleEulerEquations2D(gamma())
+
+# Trixi implements the stress tensor in deviatoric form, thus we need to
+# convert the "isotropic viscosity" to the "deviatoric viscosity"
+mu_deviatoric() = mu_bar() * 3 / 4
+equations_parabolic = CompressibleNavierStokesDiffusion2D(equations, mu = mu_deviatoric(),
+                                                          Prandtl = prandtl_number(),
+                                                          gradient_variables = GradientVariablesPrimitive())
+
+solver = DGSEM(polydeg = 3, surface_flux = flux_hlle)
+
+coordinates_min = (-domain_length / 2, -domain_length / 2)
+coordinates_max = (domain_length / 2, domain_length / 2)
+
+mesh = TreeMesh(coordinates_min, coordinates_max,
+                initial_refinement_level = 4,
+                periodicity = (false, true),
+                n_cells_max = 100_000)
+
+### Inviscid boundary conditions ###
+
+# Prescribe pure influx based on initial conditions
+function boundary_condition_inflow(u_inner, orientation, direction, x, t,
+                                   surface_flux_function,
+                                   equations::CompressibleEulerEquations2D)
+    u_cons = initial_condition_viscous_shock(x, t, equations)
+    return flux(u_cons, orientation, equations)
+end
+
+# Completely free outflow
+function boundary_condition_outflow(u_inner, orientation, direction, x, t,
+                                    surface_flux_function,
+                                    equations::CompressibleEulerEquations2D)
+    # Calculate the boundary flux entirely from the internal solution state
+    return flux(u_inner, orientation, equations)
+end
+
+boundary_conditions = (x_neg = boundary_condition_inflow,
+                       x_pos = boundary_condition_outflow,
+                       y_neg = boundary_condition_periodic,
+                       y_pos = boundary_condition_periodic)
+
+### Viscous boundary conditions ###
+# For the viscous BCs, we use the known analytical solution
+velocity_bc = NoSlip() do x, t, equations_parabolic
+    Trixi.velocity(initial_condition_viscous_shock(x,
+                                                   t,
+                                                   equations_parabolic),
+                   equations_parabolic)
+end
+
+heat_bc = Isothermal() do x, t, equations_parabolic
+    Trixi.temperature(initial_condition_viscous_shock(x,
+                                                      t,
+                                                      equations_parabolic),
+                      equations_parabolic)
+end
+
+boundary_condition_parabolic = BoundaryConditionNavierStokesWall(velocity_bc, heat_bc)
+
+boundary_conditions_parabolic = (x_neg = boundary_condition_parabolic,
+                                 x_pos = boundary_condition_parabolic,
+                                 y_neg = boundary_condition_parabolic,
+                                 y_pos = boundary_condition_parabolic)
+
+semi = SemidiscretizationHyperbolicParabolic(mesh, (equations, equations_parabolic),
+                                             initial_condition, solver;
+                                             boundary_conditions = (boundary_conditions,
+                                                                    boundary_conditions_parabolic))
+
+###############################################################################
+# ODE solvers, callbacks etc.
+
+# Create ODE problem with time span `tspan`
+tspan = (0.0, 0.5)
+ode = semidiscretize(semi, tspan)
+
+summary_callback = SummaryCallback()
+
+alive_callback = AliveCallback(alive_interval = 10)
+
+analysis_interval = 100
+analysis_callback = AnalysisCallback(semi, interval = analysis_interval)
+
+# Admissible stepsize is governed by the diffusive CFL condition.
+# Unless the advective cfl number `cfl` is not reduced to e.g. `0.1` 
+# (which is overly restrictive for this problem),
+# the diffusive CFL restricts the timestep for this problem.
+stepsize_callback = StepsizeCallback(cfl = 0.2,
+                                     cfl_diffusive = 0.2)
+
+callbacks = CallbackSet(summary_callback, alive_callback, analysis_callback,
+                        stepsize_callback)
+
+###############################################################################
+# run the simulation
+
+# Use time integrator tailored to compressible Navier-Stokes
+sol = solve(ode, CKLLSRK95_4S(), adaptive = false, dt = 1.0,
+            save_everystep = false, callback = callbacks);

examples/tree_3d_dgsem/elixir_navierstokes_viscous_shock.jl

@@ -0,0 +1,190 @@
+using OrdinaryDiffEqLowStorageRK
+using Trixi
+
+# This is the classic 1D viscous shock wave problem with analytical solution
+# for a special value of the Prandtl number.
+# The original references are:
+#
+# - R. Becker (1922)
+#   Stoßwelle und Detonation.
+#   [DOI: 10.1007/BF01329605](https://doi.org/10.1007/BF01329605)
+#
+#   English translations:
+#   Impact waves and detonation. Part I.
+#   https://ntrs.nasa.gov/api/citations/19930090862/downloads/19930090862.pdf
+#   Impact waves and detonation. Part II.
+#   https://ntrs.nasa.gov/api/citations/19930090863/downloads/19930090863.pdf
+#
+# - M. Morduchow, P. A. Libby (1949)
+#   On a Complete Solution of the One-Dimensional Flow Equations
+#   of a Viscous, Head-Conducting, Compressible Gas
+#   [DOI: 10.2514/8.11882](https://doi.org/10.2514/8.11882)
+#
+#
+# The particular problem considered here is described in
+# - L. G. Margolin, J. M. Reisner, P. M. Jordan (2017)
+#   Entropy in self-similar shock profiles
+#   [DOI: 10.1016/j.ijnonlinmec.2017.07.003](https://doi.org/10.1016/j.ijnonlinmec.2017.07.003)
+
+### Fixed parameters ###
+
+# Special value for which nonlinear solver can be omitted
+# Corresponds essentially to fixing the Mach number
+alpha = 0.5
+# We want kappa = cp * mu = mu_bar to ensure constant enthalpy
+prandtl_number() = 3 / 4
+
+### Free choices: ###
+gamma() = 5 / 3
+
+# In Margolin et al., the Navier-Stokes equations are given for an
+# isotropic stress tensor τ, i.e., ∇ ⋅ τ = μ Δu
+mu_isotropic() = 0.15
+mu_bar() = mu_isotropic() / (gamma() - 1) # Re-scaled viscosity
+
+rho_0() = 1
+v() = 1 # Shock speed
+
+domain_length = 4.0
+
+### Derived quantities ###
+
+Ma() = 2 / sqrt(3 - gamma()) # Mach number for alpha = 0.5
+c_0() = v() / Ma() # Speed of sound ahead of the shock
+
+# From constant enthalpy condition
+p_0() = c_0()^2 * rho_0() / gamma()
+
+l() = mu_bar() / (rho_0() * v()) * 2 * gamma() / (gamma() + 1) # Appropriate length scale
+
+"""
+    initial_condition_viscous_shock(x, t, equations)
+
+Classic 1D viscous shock wave problem with analytical solution
+for a special value of the Prandtl number.
+The version implemented here is described in
+- L. G. Margolin, J. M. Reisner, P. M. Jordan (2017)
+  Entropy in self-similar shock profiles
+  [DOI: 10.1016/j.ijnonlinmec.2017.07.003](https://doi.org/10.1016/j.ijnonlinmec.2017.07.003)
+"""
+function initial_condition_viscous_shock(x, t, equations)
+    y = x[1] - v() * t # Translated coordinate
+
+    # Coordinate transformation. See eq. (33) in Margolin et al. (2017)
+    chi = 2 * exp(y / (2 * l()))
+
+    w = 1 + 1 / (2 * chi^2) * (1 - sqrt(1 + 2 * chi^2))
+
+    rho = rho_0() / w
+    u = v() * (1 - w)
+    p = p_0() * 1 / w * (1 + (gamma() - 1) / 2 * Ma()^2 * (1 - w^2))
+
+    return prim2cons(SVector(rho, u, 0, 0, p), equations)
+end
+initial_condition = initial_condition_viscous_shock
+
+###############################################################################
+# semidiscretization of the ideal compressible Navier-Stokes equations
+
+equations = CompressibleEulerEquations3D(gamma())
+
+# Trixi implements the stress tensor in deviatoric form, thus we need to
+# convert the "isotropic viscosity" to the "deviatoric viscosity"
+mu_deviatoric() = mu_bar() * 3 / 4
+equations_parabolic = CompressibleNavierStokesDiffusion3D(equations, mu = mu_deviatoric(),
+                                                          Prandtl = prandtl_number(),
+                                                          gradient_variables = GradientVariablesPrimitive())
+
+solver = DGSEM(polydeg = 3, surface_flux = flux_hlle)
+
+coordinates_min = (-domain_length / 2, -domain_length / 2, -domain_length / 2)
+coordinates_max = (domain_length / 2, domain_length / 2, domain_length / 2)
+
+mesh = TreeMesh(coordinates_min, coordinates_max,
+                initial_refinement_level = 3,
+                periodicity = (false, true, true),
+                n_cells_max = 100_000)
+
+### Inviscid boundary conditions ###
+
+# Prescribe pure influx based on initial conditions
+function boundary_condition_inflow(u_inner, orientation, direction, x, t,
+                                   surface_flux_function,
+                                   equations::CompressibleEulerEquations3D)
+    u_cons = initial_condition_viscous_shock(x, t, equations)
+    return flux(u_cons, orientation, equations)
+end
+
+# Completely free outflow
+function boundary_condition_outflow(u_inner, orientation, direction, x, t,
+                                    surface_flux_function,
+                                    equations::CompressibleEulerEquations3D)
+    # Calculate the boundary flux entirely from the internal solution state
+    return flux(u_inner, orientation, equations)
+end
+
+boundary_conditions = (x_neg = boundary_condition_inflow,
+                       x_pos = boundary_condition_outflow,
+                       y_neg = boundary_condition_periodic,
+                       y_pos = boundary_condition_periodic,
+                       z_neg = boundary_condition_periodic,
+                       z_pos = boundary_condition_periodic)
+
+### Viscous boundary conditions ###
+# For the viscous BCs, we use the known analytical solution
+velocity_bc = NoSlip() do x, t, equations_parabolic
+    Trixi.velocity(initial_condition_viscous_shock(x,
+                                                   t,
+                                                   equations_parabolic),
+                   equations_parabolic)
+end
+
+heat_bc = Isothermal() do x, t, equations_parabolic
+    Trixi.temperature(initial_condition_viscous_shock(x,
+                                                      t,
+                                                      equations_parabolic),
+                      equations_parabolic)
+end
+
+boundary_condition_parabolic = BoundaryConditionNavierStokesWall(velocity_bc, heat_bc)
+
+boundary_conditions_parabolic = (x_neg = boundary_condition_parabolic,
+                                 x_pos = boundary_condition_parabolic,
+                                 y_neg = boundary_condition_parabolic,
+                                 y_pos = boundary_condition_parabolic,
+                                 z_neg = boundary_condition_parabolic,
+                                 z_pos = boundary_condition_parabolic)
+
+semi = SemidiscretizationHyperbolicParabolic(mesh, (equations, equations_parabolic),
+                                             initial_condition, solver;
+                                             boundary_conditions = (boundary_conditions,
+                                                                    boundary_conditions_parabolic))
+
+###############################################################################
+# ODE solvers, callbacks etc.
+
+# Create ODE problem with time span `tspan`
+tspan = (0.0, 0.5)
+ode = semidiscretize(semi, tspan)
+
+summary_callback = SummaryCallback()
+
+alive_callback = AliveCallback(alive_interval = 10)
+
+analysis_interval = 100
+analysis_callback = AnalysisCallback(semi, interval = analysis_interval)
+
+# For this setup, both advective and diffusive time step restrictions are relevant, i.e., 
+# may not be increased beyond the given values.
+stepsize_callback = StepsizeCallback(cfl = 0.4,
+                                     cfl_diffusive = 0.2)
+
+callbacks = CallbackSet(summary_callback, alive_callback, analysis_callback,
+                        stepsize_callback)
+
+###############################################################################
+# run the simulation
+
+# Use time integrator tailored to compressible Navier-Stokes
+sol = solve(ode, CKLLSRK95_4S(), adaptive = false, dt = 1.0,
+            save_everystep = false, callback = callbacks);