Remove option to scale grain size in lower mantle

doc/modules/changes/20240607b_dannberg

@@ -0,0 +1,8 @@
+Changed: The grain size material model no longer has the
+option to scale the grain size in the lower mantle. This
+option used to be helpful in models where the grain size
+is very different between upper and lower mantle, but
+now that ASPECT has particles, it is more accurate to
+advect the grain size on particles instead.
+<br>
+(Juliane Dannberg, 2024/06/07)

include/aspect/material_model/grain_size.h

@@ -325,7 +325,6 @@ namespace aspect
         double max_thermal_expansivity;
         unsigned int max_latent_heat_substeps;
         double min_grain_size;
-        double pv_grain_size_scaling;
 
         double diffusion_viscosity (const double temperature,
                                     const double adiabatic_temperature,

source/material_model/grain_size.cc

@@ -1217,15 +1217,7 @@ namespace aspect
                              "Units: \\si{\\meter}.");
           prm.declare_entry ("Lower mantle grain size scaling", "1.0",
                              Patterns::Double (0.),
-                             "A scaling factor for the grain size in the lower mantle. In models where the "
-                             "high grain size contrast between the upper and lower mantle causes numerical "
-                             "problems, the grain size in the lower mantle can be scaled to a larger value, "
-                             "simultaneously scaling the viscosity prefactors and grain growth parameters "
-                             "to keep the same physical behavior. Differences to the original formulation "
-                             "only occur when material with a smaller grain size than the recrystallization "
-                             "grain size cross the upper-lower mantle boundary. "
-                             "The real grain size can be obtained by dividing the model grain size by this value. "
-                             "Units: none.");
+                             "This option does not exist any more.");
           prm.declare_entry ("Advect logarithm of grain size", "false",
                              Patterns::Bool (),
                              "This option does not exist any more.");
@@ -1380,6 +1372,7 @@ namespace aspect
 
           grain_size_evolution_formulation      = Formulation::parse(prm.get("Grain size evolution formulation"));
 
+          // TODO: Remove deprecated parameter in next release.
           const std::string use_paleowattmeter  = prm.get ("Use paleowattmeter");
           Assert(use_paleowattmeter == "default",
                  ExcMessage("The parameter 'Use paleowattmeter' has been removed. "
@@ -1457,28 +1450,30 @@ namespace aspect
           max_thermal_expansivity               = prm.get_double ("Maximum thermal expansivity");
           max_latent_heat_substeps              = prm.get_integer ("Maximum latent heat substeps");
           min_grain_size                        = prm.get_double ("Minimum grain size");
-          pv_grain_size_scaling                 = prm.get_double ("Lower mantle grain size scaling");
 
           // scale recrystallized grain size, diffusion creep and grain growth prefactor accordingly
-          diffusion_creep_prefactor[diffusion_creep_prefactor.size()-1] *= std::pow(pv_grain_size_scaling,diffusion_creep_grain_size_exponent[diffusion_creep_grain_size_exponent.size()-1]);
-          grain_growth_rate_constant[grain_growth_rate_constant.size()-1] *= std::pow(pv_grain_size_scaling,grain_growth_exponent[grain_growth_exponent.size()-1]);
-          if (recrystallized_grain_size.size()>0)
-            recrystallized_grain_size[recrystallized_grain_size.size()-1] *= pv_grain_size_scaling;
+          diffusion_creep_prefactor[diffusion_creep_prefactor.size()-1] *= std::pow(1.0,diffusion_creep_grain_size_exponent[diffusion_creep_grain_size_exponent.size()-1]);
+          grain_growth_rate_constant[grain_growth_rate_constant.size()-1] *= std::pow(1.0,grain_growth_exponent[grain_growth_exponent.size()-1]);
 
           // prefactors never appear without their exponents. perform some calculations here to save time later
           for (unsigned int i=0; i<diffusion_creep_prefactor.size(); ++i)
             diffusion_creep_prefactor[i] = std::pow(diffusion_creep_prefactor[i],-1.0/diffusion_creep_exponent[i]);
           for (unsigned int i=0; i<dislocation_creep_prefactor.size(); ++i)
             dislocation_creep_prefactor[i] = std::pow(dislocation_creep_prefactor[i],-1.0/dislocation_creep_exponent[i]);
 
-          if (grain_size_evolution_formulation == Formulation::paleowattmeter)
-            boundary_area_change_work_fraction[boundary_area_change_work_fraction.size()-1] /= pv_grain_size_scaling;
+          // TODO: Remove deprecated parameters in next release.
+          const double pv_grain_size_scaling         = prm.get_double ("Lower mantle grain size scaling");
+          AssertThrow(pv_grain_size_scaling == 1.0,
+                      ExcMessage("Error: The 'Lower mantle grain size scaling' parameter "
+                                 "has been removed. Please remove it from your input file. For models "
+                                 "with large spatial variations in grain size, please advect your "
+                                 "grain size on particles."));
 
           const bool advect_log_grainsize            = prm.get_bool ("Advect logarithm of grain size");
           AssertThrow(advect_log_grainsize == false,
                       ExcMessage("Error: The 'Advect logarithm of grain size' parameter "
                                  "has been removed. Please remove it from your input file. For models "
-                                 "with large sptial variations in grain size, please advect your "
+                                 "with large spatial variations in grain size, please advect your "
                                  "grain size on particles."));
 
           if (grain_growth_activation_energy.size() != grain_growth_activation_volume.size() ||