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Refactor of vertical reconstruction with six new schemes
This refactor is motivated by i) adding a set of new reconstructions schemes
that are ready-to-use-now for remapping, but ii) will be an essential part of a
new grid generator that will use some of the new member methods available only
as a result of the refactor. The "refactor" actually duplicates many existing
schemes, leaving the original code in place to provide a period of transition
just in case there's some major reason to revert to the old style of code.
What changed
------------
- removed remapping_attic.F90
- added 16 modules name Recon1d_*.F90, which extend a base Recon1d_type.F90
- MOM_remapping.F90
- rewrote remapping_unit_tests to be tidier
- added tests for
1) invariance when remapping to/from the same grid;
2) preservation of a uniform value (many of the old schemes fail);
3) internal consistency such as monotonic ordering of values at
edges, no internal extrema, etc., but only for the new Recon1d_* schemes.
- added _Vertical_Reconstruction.dox
Six new schemes are added: C_PLM_CW, C_PLM_CWK, C_MPLM_CWK, C_EMPLM_CWK,
C_PPM_CWK, and C_EPPM_CWK.
Ten existing schemes were ported to the new class, along with their
non-monotonic behaviors or ill-formed expressions. Others can be ported later
if needed, although one result of the refactor was the discovery that none of
the existing schemes worked as desired.
The new form uses a class (Recon1d) to define a uniform API for all the
reconstruction schemes. The methods of the class include:
- init() that creates work arrays and stores parameters such as `h_neglect`
- reconstruct() that causes the reconstruction parameters to be calculated
- average() that returns the average between two points in a reconstruction
(used in the remap_src_to_sub_grid() functions)
- unit_tests() method
- check_reconstruction() checks that a reconstruction has the
properties that it should (e.g. reconstruction values are monotonic)
Theses properties are defined by each scheme, although many are shared
between schemes.
- f() that evaluates the reconstruction at a point (this will be used in the
new grid-generator).
- dfdx() that evaluates the derivative of the reconstruction at a point (this
will be used in the new grid-generator)
Testing
-------
An advantage of the new class approach is that the check_reconstruction()
method can be customized to each reconstruction, which allows us to document
which properties (e.g. monotonicity) are satisfied and which are not.
These tests use seeded random numbers which has proven useful for
debugging/development, but are not necessarily useful in the CI. Nevertheless,
I've made it part of remapping_unit_tests() so there is a template for
debugging/testing new schemes when we add them.
The base class also provides a testing type for convenience. In time, this
could (should) be moved out to a stand-alone module, so long as it does not
become cumbersome. Currently this type is hidden to avoid expanding the network
of dependencies, particularly using anything in the `framework/` directory
which is not needed by the class.
Performance
-----------
- the new class-based schemes are all faster than their counterparts in the
original code style;
- example numbers can be found in the build-test-perfmon job of this commit
(expand the "Display timing results");
- e.g. timings for PPM_HYBGEN and C_PPM_HYBGEN show a marginal (~10%) speed
up due to code style, and C_PPM_CWK has a more substantial speed up (~20%)
due to a lighter algorithm;
- I imagine we will see further speed ups if we worked on arrays rather than
columns, which is an extension that could be implemented later.
Documentation
-------------
- the new module APIs are documented;
- a new page, `_Vertical_Reconstruction.dox`, details the vertical
reconstruction schemes, tabulates the values of `REMPAPPING_SCHEME`,
and summarize some properties.- Loading branch information