calving_dt_convergence
The landice/calving_dt_convergence test group supports tests for
assessing the timestep convergence of calving physics in MALI. The tests all
use pre-generated meshes.
The test group includes many individual test cases that cover combinations of
three meshes (mismip+, humboldt and thwaites), three calving laws
(specified_calving_velocity, von_Mises_stress and eigencalving),
and two velocity settings (none and FO). The
specified_calving_velocity cases are only available with none
velocity because the FO combination is not used in the code.
config options
There currently are no config options.
dt_convergence_test
Cases in this test group have names such as
landice/calving_dt_convergence/humboldt.von_Mises_stress.none or
landice/calving_dt_convergence/thwaites.eigencalving.FO. Each one runs
short integrations repeatedly with different values for the fraction of the
calving CFL limit applied in the adaptive timestepper. Time series of the
total calving flux and the calving CFL to actual timestep ratio are then
plotted, as well as summary of the number of calving warnings for each choice
of calving CFL fraction (see below).
Example results of calving dt test for the
humboldt.specified_calving_velocity.none test case. The top plot
shows the total calving flux over time for different choices of
the calving CFL fraction. Results should be similar for small
fraction values. As the fraction is increased,
significant differences can be seen, indicating values greater than
about 1.0 are less accurate. The second panel shows the cumulative
total calving flux. The third panel shows the actual dt used by the
adaptive timestepper divided by the timestep limit due to the
calving CFL. This allows assessment of the current implementation
limitation that the calving CFL limit is lagged by one time step;
if this value is significantly less than the fraction specified,
the method of lagging the calving CFL is not accurate. The final
panel shows the number of calving warnings (left axis) and the
fraction of total timesteps with warnings (right axis) for each
value of the calving CFL fraction that was run. Warnings are
triggered when the calving routine is unable to calve more than 1%
of the calving volume it was asked to calve.