A set of libraries and executables creating a workflow for performing
gradient-based optimisation loops. The main executable (adjointOptimisationFoam)
solves the flow (primal) equations, followed by the adjoint equations and,
eventually, the computation of sensitivity derivatives.
Current functionality supports the solution of the adjoint equations for
incompressible turbulent flows, including the adjoint to the Spalart-Allmaras
turbulence model and the adjoint to the nutUSpaldingWallFunction, [1], [2].
Sensitivity derivatives are computed with respect to the normal displacement of
boundary wall nodes/faces (the so-called sensitivity maps) following the
Enhanced Surface Integrals (E-SI) formulation, [3].
The software was developed by PCOpt/NTUA and FOSS GP, with contributions from
Dr. Evangelos Papoutsis-Kiachagias,
Konstantinos Gkaragounis,
Professor Kyriakos Giannakoglou,
Andy Heather
and contributions in earlier version from
Dr. Ioannis Kavvadias,
Dr. Alexandros Zymaris,
Dr. Dimitrios Papadimitriou
[1] A.S. Zymaris, D.I. Papadimitriou, K.C. Giannakoglou, and C. Othmer.
Continuous adjoint approach to the Spalart-Allmaras turbulence model for
incompressible flows. Computers & Fluids, 38(8):1528–1538, 2009.
[2] E.M. Papoutsis-Kiachagias and K.C. Giannakoglou. Continuous adjoint methods
for turbulent flows, applied to shape and topology optimization: Industrial
applications. 23(2):255–299, 2016.
[3] I.S. Kavvadias, E.M. Papoutsis-Kiachagias, and K.C. Giannakoglou. On the
proper treatment of grid sensitivities in continuous adjoint methods for shape
optimization. Journal of Computational Physics, 301:1–18, 2015.
Integration into the official OpenFOAM release by OpenCFD
- when running in serial but within a processor directory,
argList::globalPath() is to be used instead of Time.globalPath()
For other cases there is no difference.
- when windows portable executables (.exe or .dll) files are loaded,
their dependent libraries not fully loaded. For OpenFOAM this means
that the static constructors which are responsible for populating
run-time selection tables are not triggered, and most of the run-time
selectable models will simply not be available.
Possible Solution
=================
Avoid this problem by defining an additional library symbol such as
the following:
extern "C" void libName_Load() {}
in the respective library, and tag this symbol as 'unresolved' for
the linker so that it will attempt to resolve it at run-time by
loading the known libraries until it finds it. The link line would
resemble the following:
-L/some/path -llibName -ulibName_Load
Pros:
- Allows precise control of forced library loading
Cons:
- Moderately verbose adjustment of some source files (even with macro
wrapping for the declaration).
- Adjustment of numerous Make/options files and somewhat ad hoc
in nature.
- Requires additional care when implementing future libraries and/or
applications.
- This is the solution taken by the symscape patches (Richard Smith)
Possible Solution
=================
Avoid this problem by simply force loading all linked libraries.
This is done by "scraping" the information out of the respective
Make/options file (after pre-processing) and using that to define
the library list that will be passed to Foam::dlOpen() at run-time.
Pros:
- One-time (very) minimal adjustment of the sources and wmake toolchain
- Automatically applies to future applications
Cons:
- Possibly larger memory footprint of application (since all dependent
libraries are loaded).
- Possible impact on startup time (while loading libraries)
- More sensitive to build failures. Since the options files are
read and modified based on the existence of the dependent
libraries as a preprocessor step, if the libraries are initially
unavailable for the first attempt at building the application,
the dependencies will be inaccurate for later (successful) builds.
- This is solution taken by the bluecape patches (Bruno Santos)
Adopted Solution
================
The approach taken by Bruno was adopted in a modified form since
this appears to be the most easily maintained.
Additional Notes
================
It is always possible to solve this problem by defining a corresponding
'libs (...)' entry in the case system/controlDict, which forces a dlOpen
of the listed libraries. This is obviously less than ideal for large-scale
changes, but can work to resolve an individual problem.
The peldd utility (https://github.com/gsauthof/pe-util), which is
also packaged as part of MXE could provide yet another alternative.
Like ldd it can be used to determine the library dependencies of
binaries or libraries. This information could be used to define an
additional load layer for Windows.
- adjust naming of quaternion 'rotationSequence' to be 'eulerOrder'
to reflect its purpose.
- provide rotation matrices directly for these rotation orders in
coordinateRotations::euler for case in which the rotation tensor
is required but not a quaternion.
- Eg, with surface writers now in surfMesh, there are fewer libraries
depending on conversion and sampling.
COMP: regularize linkage ordering and avoid some implicit linkage (#1238)
- remove writeGeometry() in favour of write() and make it pure virtual
so that all writers must explicitly deal with it.
- establish proxy extension at construction time and treated as an
invariant thereafter. This avoids potentially surprising changes in
behaviour when writing.
- While a rectilinear mesh can be created with blockMesh, not every mesh
created with blockMesh will satisfy the requirements for being a
rectilinear mesh.
This alternative to blockMesh uses a single block that is aligned
with the xy-z directions and specifications of the control points,
mesh divisions and expansion ratios. For example,
x
{
points ( -13.28 -0.10 6.0 19.19 );
nCells ( 10 12 10 );
ratios ( 0.2 1 5 );
}
y { ... }
z { ... }
With only one block, the boundary patch definition is simple and the
canonical face number is used directly. For example,
inlet
{
type patch;
faces ( 0 );
}
outlet
{
type patch;
faces ( 1 );
}
sides
{
type patch;
faces ( 2 3 );
}
...
- After a mesh is defined, it is trivial to retrieve mesh-related
information such as cell-volume, cell-centres for any i-j-k location
without an actual polyMesh.
STYLE: remove -noFunctionObjects from blockMesh
- no time loop, so function objects cannot be triggered anyhow.
- The writers have changed from being a generic state-less set of
routines to more properly conforming to the normal notion of a writer.
These changes allow us to combine output fields (eg, in a single
VTK/vtp file for each timestep).
Parallel data reduction and any associated bookkeeping is now part
of the surface writers.
This improves their re-usability and avoids unnecessary
and premature data reduction at the sampling stage.
It is now possible to have different output formats on a per-surface
basis.
- A new feature of the surface sampling is the ability to "store" the
sampled surfaces and fields onto a registry for reuse by other
function objects.
Additionally, the "store" can be triggered at the execution phase
as well
- can now safely use labelList::null() instead of emptyLabelList for
return values. No special treatment required for lists.
Possible replacements:
if (notNull(list) && list.size()) -> if (list.size())
if (isNull(list) || list.empty()) -> if (list.empty())
The receiver may still wish to handle differently to distinguish
between a null list and an empty list, but no additional special
protection is required when obtaining sizes, traversing, outputting
etc.
- changed ensightOutput from a class solely comprising static methods to
a namespace and added in sub-namespaces Detail and Serial.
This makes it easier to "mix-in" functions at different levels.
Refactored and combined some serial/parallel code where possible.
The general ensightOutput namespace has now shifted to be in the
fileFormats lib, while leaving volField outputs in the conversion lib
and cloud outputs in the lagrangian-intermediate lib.
The ensightCloud namespace is now simply folded into the new
ensightOutput namespace.
These changes clean up some code, reduce fragmentation and
duplication and removes the previous libconversion dependency for
sampling.
- use int for ensight nTypes constexpr
Note: issue #1176 is unaffected except for the change in file name:
ensightOutputTemplates.C -> ensightOutputVolFieldTemplates.C
- changed the sectorCoeffs keyword to 'point' from 'axisPt'
for more similarity with other dictionaries.
Continue to accept 'axisPt' for compatibility.
