5: Shock and reconstructed-face handling

docs/source/changelog.rst

@@ -70,6 +70,12 @@ conservative energy transfer continues to modify only the EOS pressure; the
 turbulent contribution is evaluated from its remapped face state. Split/merge
 AMR does not currently support RSP2.
 
+Cell-centered Riemann hydrodynamics can now reduce chemical diffusion across
+resolved shocks using the default-off ``Riemann_shock_D_mix_reduction_on`` and
+``Riemann_shock_D_mix_reduction_full_on`` controls. Corresponding compression,
+pressure-jump, shock-strength, and diffusion-factor profile columns are
+available for diagnostics.
+
 .. _Bug Fixes main:
 
 Bug Fixes

star/defaults/controls_dev.defaults

@@ -225,6 +225,35 @@
     use_TDC_enthalpy_flux_limiter = .false.
 
 
+      ! Riemann_shock_D_mix_reduction_on
+      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+      ! When the Riemann shock mixing reduction is enabled, leave chemical
+      ! diffusion unchanged at shock strengths less than or equal to this
+      ! value. The strength is the minimum of the signed compression Mach
+      ! number and the HLLC pressure jump.
+
+      ! ::
+
+    Riemann_shock_D_mix_reduction_on = 0d0
+
+
+      ! Riemann_shock_D_mix_reduction_full_on
+      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+      ! For positive values with ``u_flag``, smoothly reduce the final chemical
+      ! diffusion coefficient at compressive Riemann shock faces. The reduction
+      ! changes from zero at ``Riemann_shock_D_mix_reduction_on`` to complete at
+      ! this value using a quintic smootherstep. Nonpositive values disable the
+      ! reduction. When positive, this value must be greater than the onset.
+      ! This does not change the MLT/TDC velocity, convective luminosity, or
+      ! eddy viscosity.
+
+      ! ::
+
+    Riemann_shock_D_mix_reduction_full_on = -1d0
+
+
       ! use_face_reconstruction
       ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

star/defaults/profile_columns.list

@@ -737,6 +737,10 @@
    !PII_face
    !Ptrb
    !Pvsc
+   !Riemann_shock_compression ! max(0, (u_inner-u_outer)/cs_face)
+   !Riemann_shock_pressure_jump ! max(0, P_face/min(P_inner,P_outer) - 1)
+   !Riemann_shock_strength ! minimum of compression and pressure jump
+   !Riemann_shock_D_mix_factor ! factor applied to final chemical D_mix
    !Uq
    !Y_face
 

star/dev_cases_test_TDC/dev_TDC_noh_riemann/Makefile

@@ -0,0 +1 @@
+include $(MESA_DIR)/star/work/Makefile

star/dev_cases_test_TDC/dev_TDC_noh_riemann/ck

@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+
+export MESA_DIR=../../..
+source "${MESA_DIR}/star/test_suite/test_suite_helpers"
+
+check_one

star/dev_cases_test_TDC/dev_TDC_noh_riemann/clean

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+
+export MESA_DIR=../../..
+
+make clean