added isostress averaging to CompositeViscoPlastic

doc/modules/changes/20240725_myhill

@@ -0,0 +1,7 @@
+New: The CompositeViscoPlastic rheology in ASPECT now
+allows the user to select isostress (Reuss) or
+isostrain (Voigt) averaging of viscosities for
+multicomponent materials via the parameter
+"Viscosity averaging scheme".
+<br>
+(Bob Myhill, 2024/07/25)

include/aspect/material_model/rheology/composite_visco_plastic.h

@@ -83,6 +83,34 @@ namespace aspect
  const std::vector<double> &phase_function_values = std::vector<double>(),
  const std::vector<unsigned int> &n_phase_transitions_per_composition = std::vector<unsigned int>()) const;
 
+ /**
+ * Compute the isostress viscosity over all compositional fields
+ * based on the composite viscous creep law.
+ * If @p expected_n_phases_per_composition points to a vector of
+ * unsigned integers this is considered the number of phase transitions
+ * for each compositional field and viscosity will be first computed on
+ * each phase and then averaged for each compositional field.
+ */
+ double
+ compute_isostress_viscosity (const double pressure,
+ const double temperature,
+ const double grain_size,
+ const std::vector<double> &volume_fractions,
+ const SymmetricTensor<2,dim> &strain_rate,
+ std::vector<double> &partial_strain_rates,
+ const std::vector<double> &phase_function_values = std::vector<double>(),
+ const std::vector<unsigned int> &n_phase_transitions_per_composition = std::vector<unsigned int>()) const;
+
+ /**
+ * Compute the total strain rate and the first derivative of log strain rate
+ * with respect to log viscoplastic stress from individual log strain rate components
+ * over all compositional fields. Also updates the partial_strain_rates vector
+ */
+ std::pair<double, double>
+ calculate_isostress_log_strain_rate_and_derivative(const std::vector<std::array<std::pair<double, double>, 4>> &logarithmic_strain_rates_and_stress_derivatives,
+ const double viscoplastic_stress,
+ std::vector<double> &partial_strain_rates) const;
+
  /**
  * Compute the compositional field viscosity
  * based on the composite viscous creep law.
@@ -107,11 +135,19 @@ namespace aspect
  * Also updates the partial_strain_rates vector
  */
  std::pair<double, double>
- calculate_log_strain_rate_and_derivative(const std::array<std::pair<double, double>, 4> &logarithmic_strain_rates_and_stress_derivatives,
- const double viscoplastic_stress,
- std::vector<double> &partial_strain_rates) const;
+ calculate_composition_log_strain_rate_and_derivative(const std::array<std::pair<double, double>, 4> &logarithmic_strain_rates_and_stress_derivatives,
+  const double viscoplastic_stress,
+  std::vector<double> &partial_strain_rates) const;
 
  private:
+ /**
+ * Enumeration for selecting which type of viscosity averaging to use.
+ */
+ enum ViscosityAveragingScheme
+ {
+ isostrain,
+ isostress
+ } viscosity_averaging_scheme;
 
  /**
  * Whether to use different deformation mechanisms

tests/composite_viscous_outputs.cc

@@ -47,6 +47,7 @@ void f(const aspect::SimulatorAccess<dim> &simulator_access,
  composite_creep = std::make_unique<Rheology::CompositeViscoPlastic<dim>>();
  composite_creep->initialize_simulator (simulator_access.get_simulator());
  composite_creep->declare_parameters(prm);
+ prm.set("Viscosity averaging scheme", "isostrain");
  prm.set("Include diffusion creep in composite rheology", "true");
  prm.set("Include dislocation creep in composite rheology", "true");
  prm.set("Include Peierls creep in composite rheology", "true");

tests/composite_viscous_outputs_isostress.cc

@@ -0,0 +1,238 @@
+/*
+ Copyright (C) 2022 - 2023 by the authors of the ASPECT code.
+
+ This file is part of ASPECT.
+
+ ASPECT is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ ASPECT is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with ASPECT; see the file LICENSE. If not see
+ <http://www.gnu.org/licenses/>.
+*/
+
+#include <aspect/simulator.h>
+#include <aspect/material_model/rheology/composite_visco_plastic.h>
+#include <aspect/simulator_signals.h>
+#include <iostream>
+
+template <int dim>
+void f(const aspect::SimulatorAccess<dim> &simulator_access,
+ aspect::Assemblers::Manager<dim> &)
+{
+ // This function tests whether the composite creep rheology is producing
+ // the correct composite viscosity and partial strain rates corresponding to
+ // the different creep mechanisms incorporated into the rheology.
+ // It is assumed that each individual creep mechanism has already been tested.
+
+ using namespace aspect::MaterialModel;
+
+ // First, we set up a few objects which are used by the rheology model.
+ aspect::ParameterHandler prm;
+
+ const std::vector<std::string> list_of_composition_names = simulator_access.introspection().get_composition_names();
+ auto n_phases = std::make_unique<std::vector<unsigned int>>(1); // 1 phase per composition
+ const unsigned int composition = 0;
+ const std::vector<double> volume_fractions = {0.6, 0.4};
+ const std::vector<double> phase_function_values = std::vector<double>();
+ const std::vector<unsigned int> n_phase_transitions_per_composition = std::vector<unsigned int>(1);
+
+ // Next, we initialise instances of the composite rheology and
+ // individual creep mechanisms.
+ std::unique_ptr<Rheology::CompositeViscoPlastic<dim>> composite_creep;
+ composite_creep = std::make_unique<Rheology::CompositeViscoPlastic<dim>>();
+ composite_creep->initialize_simulator (simulator_access.get_simulator());
+ composite_creep->declare_parameters(prm);
+ prm.set("Viscosity averaging scheme", "isostress");
+ prm.set("Include diffusion creep in composite rheology", "true");
+ prm.set("Include dislocation creep in composite rheology", "true");
+ prm.set("Include Peierls creep in composite rheology", "true");
+ prm.set("Include Drucker Prager plasticity in composite rheology", "true");
+ prm.set("Peierls creep flow law", "viscosity approximation");
+ prm.set("Maximum yield stress", "5e8");
+ composite_creep->parse_parameters(prm);
+
+ std::unique_ptr<Rheology::DiffusionCreep<dim>> diffusion_creep;
+ diffusion_creep = std::make_unique<Rheology::DiffusionCreep<dim>>();
+ diffusion_creep->initialize_simulator (simulator_access.get_simulator());
+ diffusion_creep->declare_parameters(prm);
+ diffusion_creep->parse_parameters(prm);
+
+ std::unique_ptr<Rheology::DislocationCreep<dim>> dislocation_creep;
+ dislocation_creep = std::make_unique<Rheology::DislocationCreep<dim>>();
+ dislocation_creep->initialize_simulator (simulator_access.get_simulator());
+ dislocation_creep->declare_parameters(prm);
+ dislocation_creep->parse_parameters(prm);
+
+ std::unique_ptr<Rheology::PeierlsCreep<dim>> peierls_creep;
+ peierls_creep = std::make_unique<Rheology::PeierlsCreep<dim>>();
+ peierls_creep->initialize_simulator (simulator_access.get_simulator());
+ peierls_creep->declare_parameters(prm);
+ peierls_creep->parse_parameters(prm);
+
+ std::unique_ptr<Rheology::DruckerPragerPower<dim>> drucker_prager_power;
+ drucker_prager_power = std::make_unique<Rheology::DruckerPragerPower<dim>>();
+ drucker_prager_power->initialize_simulator (simulator_access.get_simulator());
+ drucker_prager_power->declare_parameters(prm);
+ prm.set("Maximum yield stress", "5e8");
+ drucker_prager_power->parse_parameters(prm);
+ Rheology::DruckerPragerParameters p = drucker_prager_power->compute_drucker_prager_parameters(composition, phase_function_values, n_phase_transitions_per_composition);
+
+ // The creep components are arranged in series with each other.
+ // This package of components is then arranged in parallel with
+ // a strain rate limiter with a constant viscosity lim_visc.
+ // The whole system is then arranged in series with a viscosity limiter with
+ // viscosity max_visc.
+ // lim_visc is equal to (min_visc*max_visc)/(max_visc - min_visc)
+ double min_visc = prm.get_double("Minimum viscosity");
+ double max_visc = prm.get_double("Maximum viscosity");
+ double lim_visc = (min_visc*max_visc)/(max_visc - min_visc);
+
+ // Assign values to the variables which will be passed to compute_viscosity
+ // The test involves pure shear calculations at 1 GPa and variable temperature
+ double temperature;
+ const double pressure = 1.e9;
+ const double grain_size = 1.e-3;
+ SymmetricTensor<2,dim> strain_rate;
+ strain_rate[0][0] = -1e-11;
+ strain_rate[0][1] = 0.;
+ strain_rate[1][1] = 1e-11;
+ strain_rate[2][0] = 0.;
+ strain_rate[2][1] = 0.;
+ strain_rate[2][2] = 0.;
+
+ std::cout << "temperature (K) eta (Pas) creep stress (Pa) edot_ii (/s) edot_ii fractions (diff, disl, prls, drpr, max)" << std::endl;
+
+ // Loop through strain rates, tracking whether there is a discrepancy in
+ // the decomposed strain rates.
+ bool error = false;
+ double viscosity;
+ double total_strain_rate;
+ double creep_strain_rate;
+ double creep_stress;
+ double diff_stress;
+ double disl_stress;
+ double prls_stress;
+ double drpr_stress;
+ std::vector<double> partial_strain_rates(5, 0.);
+
+ for (unsigned int i=0; i <= 10; i++)
+ {
+ temperature = 1000. + i*100.;
+
+ // Compute the viscosity
+ viscosity = composite_creep->compute_isostress_viscosity(pressure, temperature, grain_size, volume_fractions, strain_rate, partial_strain_rates);
+ total_strain_rate = std::accumulate(partial_strain_rates.begin(), partial_strain_rates.end(), 0.);
+
+ // The creep strain rate is calculated by subtracting the strain rate
+ // of the max viscosity dashpot from the total strain rate
+ // The creep stress is then calculated by subtracting the stress running
+ // through the strain rate limiter from the total stress
+ creep_strain_rate = total_strain_rate - partial_strain_rates[4];
+ creep_stress = 2.*(viscosity*total_strain_rate - lim_visc*creep_strain_rate);
+
+ // Print the output
+ std::cout << temperature << ' ' << viscosity << ' ' << creep_stress << ' ' << total_strain_rate;
+ for (unsigned int i=0; i < partial_strain_rates.size(); ++i)
+ {
+ std::cout << ' ' << partial_strain_rates[i]/total_strain_rate;
+ }
+ std::cout << std::endl;
+
+ // The following lines test that each individual creep mechanism
+ // experiences the same creep stress
+
+ // Each creep mechanism should experience the same stress
+ diff_stress = 2.*partial_strain_rates[0]*diffusion_creep->compute_viscosity(pressure, temperature, grain_size, composition);
+ disl_stress = 2.*partial_strain_rates[1]*dislocation_creep->compute_viscosity(partial_strain_rates[1], pressure, temperature, composition);
+ prls_stress = 2.*partial_strain_rates[2]*peierls_creep->compute_viscosity(partial_strain_rates[2], pressure, temperature, composition);
+ if (partial_strain_rates[3] > 0.)
+ {
+ drpr_stress = 2.*partial_strain_rates[3]*drucker_prager_power->compute_viscosity(p.cohesion,
+ p.angle_internal_friction,
+ pressure,
+ partial_strain_rates[3],
+ p.max_yield_stress);
+ }
+ else
+ {
+ drpr_stress = creep_stress;
+ }
+
+ if ((std::fabs((diff_stress - creep_stress)/creep_stress) > 1e-6)
+ || (std::fabs((disl_stress - creep_stress)/creep_stress) > 1e-6)
+ || (std::fabs((prls_stress - creep_stress)/creep_stress) > 1e-6)
+ || (std::fabs((drpr_stress - creep_stress)/creep_stress) > 1e-6))
+ {
+ error = true;
+ std::cout << " creep stress: " << creep_stress;
+ std::cout << " diffusion stress: " << diff_stress;
+ std::cout << " dislocation stress: " << disl_stress;
+ std::cout << " peierls stress: " << prls_stress;
+ std::cout << " drucker prager stress: " << drpr_stress << std::endl;
+ }
+ }
+
+ if (error)
+ {
+ std::cout << " Error: The individual creep stresses differ by more than the required tolerance." << std::endl;
+ std::cout << "Some parts of the test were not successful." << std::endl;
+ }
+ else
+ {
+ std::cout << "OK" << std::endl;
+ }
+
+}
+
+template <>
+void f(const aspect::SimulatorAccess<2> &,
+ aspect::Assemblers::Manager<2> &)
+{
+ AssertThrow(false,dealii::ExcInternalError());
+}
+
+template <int dim>
+void signal_connector (aspect::SimulatorSignals<dim> &signals)
+{
+ using namespace dealii;
+ std::cout << "* Connecting signals" << std::endl;
+ signals.set_assemblers.connect (std::bind(&f<dim>,
+ std::placeholders::_1,
+ std::placeholders::_2));
+}
+
+
+using namespace aspect;
+
+
+void declare_parameters(const unsigned int dim,
+ ParameterHandler &prm)
+{
+ prm.enter_subsection("Compositional fields");
+ {
+ prm.declare_entry("Number of fields","1", Patterns::Integer());
+ }
+ prm.leave_subsection();
+}
+
+
+
+void parameter_connector ()
+{
+ SimulatorSignals<2>::declare_additional_parameters.connect (&declare_parameters);
+ SimulatorSignals<3>::declare_additional_parameters.connect (&declare_parameters);
+}
+
+
+
+ASPECT_REGISTER_SIGNALS_CONNECTOR(signal_connector<2>,
+ signal_connector<3>)
+ASPECT_REGISTER_SIGNALS_PARAMETER_CONNECTOR(parameter_connector)

tests/composite_viscous_outputs_isostress.prm

@@ -0,0 +1,80 @@
+# This test checks whether the composite viscous rheology
+# plugin produces the correct composite viscosity and
+# decomposed strain rates.
+
+set Additional shared libraries = tests/libcomposite_viscous_outputs_isostress.so
+set Dimension = 3
+set End time = 0
+set Use years in output instead of seconds = true
+set Nonlinear solver scheme = no Advection, no Stokes
+
+# Model geometry (100x100 km, 10 km spacing)
+subsection Geometry model
+ set Model name = box
+
+ subsection Box
+ set X repetitions = 10
+ set Y repetitions = 10
+ set X extent = 100e3
+ set Y extent = 100e3
+ end
+end
+
+# Mesh refinement specifications
+subsection Mesh refinement
+ set Initial adaptive refinement = 0
+ set Initial global refinement = 0
+ set Time steps between mesh refinement = 0
+end
+
+# Boundary classifications (fixed T boundaries, prescribed velocity)
+
+# Temperature boundary and initial conditions
+subsection Boundary temperature model
+ set Fixed temperature boundary indicators = bottom, top, left, right
+ set List of model names = box
+
+ subsection Box
+ set Bottom temperature = 273
+ set Left temperature = 273
+ set Right temperature = 273
+ set Top temperature = 273
+ end
+end
+
+# Velocity on boundaries characterized by functions
+subsection Boundary velocity model
+ set Prescribed velocity boundary indicators = bottom y: function, top y: function, left x: function, right x: function
+
+ subsection Function
+ set Variable names = x,y,z
+ set Function constants = m=0.0005, year=1
+ set Function expression = if (x<50e3 , -1*m/year, 1*m/year); if (y<50e3 , 1*m/year, -1*m/year);0
+ end
+end
+
+subsection Initial temperature model
+ set Model name = function
+
+ subsection Function
+ set Function expression = 273
+ end
+end
+
+# Material model
+subsection Material model
+ set Model name = visco plastic
+
+ subsection Visco Plastic
+ set Angles of internal friction = 30.
+ end
+end
+
+# Gravity model
+subsection Gravity model
+ set Model name = vertical
+
+ subsection Vertical
+ set Magnitude = 10.0
+ end
+end