Implement FB_LTS local time-stepping scheme for single layer MPAS-O

E3SM-Project · Mar 1, 2024 · 5263736 · 5263736
1 parent c8208a4
commit 5263736
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Showing 9 changed files with 2,010 additions and 8 deletions.
diff --git a/components/mpas-ocean/src/Registry.xml b/components/mpas-ocean/src/Registry.xml
@@ -202,7 +202,7 @@
 		/>
 		<nml_option name="config_time_integrator" type="character" default_value="split_explicit_ab2"
 					description="Time integration method."
-					possible_values="'split_explicit', 'RK4', 'unsplit_explicit', 'split_implicit', 'LTS', 'split_explicit_ab2'"
+					possible_values="'split_explicit', 'RK4', 'unsplit_explicit', 'split_implicit', 'LTS', 'FB_LTS', 'split_explicit_ab2'"
 		/>
 		<nml_option name="config_number_of_time_levels" type="integer" default_value="2"
 					description="The number of time levels in the time-stepping scheme. This is used for array allocation."
@@ -1196,6 +1196,20 @@
 					possible_values="Any positive integer greater than or equal to one. A value of one employs the same dt in all regions."
 		/>
 	</nml_record>
+    <nml_record name="forward_backward" mode="forward">
+		<nml_option name="config_fb_weight_1" type="real" default_value="0.531"
+					description="The forward-backward weight for the first stage of FB-RK(3,2), used in FB_LTS."
+					possible_values="Any positive real number less than or equal to one."
+		/>
+		<nml_option name="config_fb_weight_2" type="real" default_value="0.531"
+					description="The forward-backward weight for the second stage of FB-RK(3,2), used in FB_LTS."
+					possible_values="Any positive real number less than or equal to one."
+		/>
+		<nml_option name="config_fb_weight_3" type="real" default_value="0.313"
+					description="The forward-backward weight for the third stage of FB-RK(3,2), used in FB_LTS."
+					possible_values="Any positive real number less than or equal to one."
+		/>
+	</nml_record>
 	<nml_record name="pressure_gradient" mode="forward">
 		<nml_option name="config_pressure_gradient_type" type="character" default_value="pressure_and_zmid"
 					description="Form of pressure gradient terms in momentum equation. For most applications, the gradient of pressure and layer mid-depth are appropriate.  For isopycnal coordinates, one may use the gradient of the Montgomery potential.  The sea surface height gradient (ssh_gradient) option is for barotropic, depth-averaged pressure."

diff --git a/components/mpas-ocean/src/mode_forward/Makefile b/components/mpas-ocean/src/mode_forward/Makefile
@@ -6,13 +6,19 @@ OBJS = mpas_ocn_forward_mode.o \
        mpas_ocn_time_integration_si.o \
        mpas_ocn_time_integration_split.o \
        mpas_ocn_time_integration_lts.o \
+       mpas_ocn_time_integration_fblts.o \
        mpas_ocn_time_integration_split_ab2.o
 
 all: forward_mode
 
 forward_mode: $(OBJS) 
 
-mpas_ocn_time_integration.o: mpas_ocn_time_integration_rk4.o mpas_ocn_time_integration_si.o  mpas_ocn_time_integration_split.o mpas_ocn_time_integration_lts.o mpas_ocn_time_integration_split_ab2.o
+mpas_ocn_time_integration.o: mpas_ocn_time_integration_rk4.o \
+	                         mpas_ocn_time_integration_si.o \
+							 mpas_ocn_time_integration_split.o \
+							 mpas_ocn_time_integration_lts.o \
+							 mpas_ocn_time_integration_fblts.o \
+							 mpas_ocn_time_integration_split_ab2.o
 
 mpas_ocn_time_integration_rk4.o: 
 
@@ -27,6 +33,7 @@ mpas_ocn_forward_mode.o: mpas_ocn_time_integration.o \
                          mpas_ocn_time_integration_si.o \
                          mpas_ocn_time_integration_split.o \
                          mpas_ocn_time_integration_lts.o \
+					     mpas_ocn_time_integration_fblts.o \
                          mpas_ocn_time_integration_split_ab2.o
 
 clean:

diff --git a/components/mpas-ocean/src/mode_forward/mpas_ocn_time_integration.F b/components/mpas-ocean/src/mode_forward/mpas_ocn_time_integration.F
@@ -34,6 +34,7 @@ module ocn_time_integration
    use ocn_time_integration_split
    use ocn_time_integration_si
    use ocn_time_integration_lts
+   use ocn_time_integration_fblts
    use ocn_time_integration_split_ab2
 
 
@@ -72,7 +73,8 @@ module ocn_time_integration
        timeIntSemiImplicit     = 3, &! Semi-implicit
        timeIntRK4              = 4, &! 4th-order Runge-Kutta
        timeIntLTS              = 5, &! local time-stepping
-       timeIntSplitExplicitAB2 = 6   ! split-explicit AB2 baroclinic
+       timeIntFBLTS            = 6, &! forward-backward lts
+       timeIntSplitExplicitAB2 = 7   ! split-explicit AB2 baroclinic
 
 !***********************************************************************
 
@@ -136,6 +138,8 @@ subroutine ocn_timestep(domain, dt, timeStamp)!{{{
          call ocn_time_integrator_rk4(domain, dt)
       case (timeIntLTS)
          call ocn_time_integrator_lts(domain, dt)
+      case (timeIntFBLTS)
+         call ocn_time_integrator_fblts(domain, dt)
       case (timeIntSplitExplicitAB2)
          call ocn_time_integrator_split_ab2(domain, dt)
       end select
@@ -232,6 +236,10 @@ subroutine ocn_timestep_init(domain, dt, err)!{{{
       case ('LTS')
          timeIntegratorChoice = timeIntLTS
          call ocn_time_integration_lts_init(domain)
+
+      case ('FB_LTS')
+         timeIntegratorChoice = timeIntFBLTS
+         call ocn_time_integration_fblts_init(domain)
 
       case ('split_explicit_ab2')
          timeIntegratorChoice = timeIntSplitExplicitAB2