simplify the implementation of these methods.
\item Previously, the \texttt{parallel::distributed::ContinuousQuadratureDataTransfer}
class, which transfers local quadrature point data onto the
- children of newly refined cells, did not allow different regions of the
- triangulation store quadrature data of different lengths. This release lifts
+ children of newly refined cells, did not allow different cells
+ to store quadrature data of different lengths. This release lifts
this restriction, which enables efficient quadrature data storage and data
transfer within a triangulation containing multiple material models, each with
their own number of local state variables and history variables.
As an example, in a solid mechanics simulation, we can assign a hyper-elastic
- material model can be assigned to a region of the mesh with no associated
- history variables while in another part of the triangulation we incorporate an
+ material model to a region of the mesh with no associated
+ history variables, while in another part of the triangulation we incorporate an
elasto-plastic constitutive model, requiring the storage of local plasticity
data at quadrature points.
- During each refinement of the mesh, we can use
+ During each refinement of the mesh, we can then use
\texttt{ContinuousQuadratureDataTransfer} to transfer and interpolate
plasticity data from parent cells to their children, ignoring the cells
with the hyper-elastic constitutive model.
\subsection{Support for particle-based methods}
\label{subsec:particles}
-Support for particles was originally introduced in \dealii{} version 9.0. In \dealii,
+Support for particles was originally introduced in \dealii{} version 9.0. These
particles can be used as passive tracers, or as part of more complex
models such as those based on Particle-In-Cells (PIC) approaches \cite{GLHPB18}.
-With the current release, the support for particles has been further expanded: New parallel
- insertion mechanisms and a basic interface to post-process particles have
+With the current release, support for particles has been further expanded: New parallel
+insertion mechanisms and a basic interface to post-process particles have
been added, effectively making their usage more flexible and enabling a larger
-range of use cases (e.g. immersed boundaries in step-70).
-
-Through the addition of the \texttt{Particles::ParticleHandler::insert\_global\_particles} member function,
- particles can now be inserted in parallel from a vector of points even if these points do not lie
- on the subdomain from which the insertion is called. This operation requires extensive
- communication between the processes to locate the MPI process the cell in which the particle
- is located. However, it is made significantly faster through the usage of bounding boxes
- that surround the cells of each subdomain.
- This function also takes care of transferring the properties attached to the particles to their new owner.
- This new capacity enables particle generators that insert particles at the location
- of the support points (\texttt{Particles::Generator::dof\_support\_points}) and at the quadrature points (\texttt{Particles::Generator::quadrature\_points}) of a
- possibly non-matching triangulation. Consequently, complex particle patterns can be inserted
- using unstructured hexahedral grids generated outside of \dealii{}.
+range of use cases (such as the immersed boundaries in step-70, see below).
+
+Through the addition of the \texttt{Particles::ParticleHandler::insert\_global\_particles()} member function,
+particles can now be inserted in parallel from a vector of points even if these points do not lie
+on the subdomain from which the insertion is called. This operation requires extensive
+communication between the processes to locate the MPI process that
+owns the cell in which the particle
+is located. However, it is made significantly faster through the usage of bounding boxes
+that surround the cells of each subdomain.
+This function also takes care of transferring the properties attached to the particles to their new owner.
+This new capability enables particle generators that insert particles at the location
+of the support points (\texttt{Particles::Generator::dof\_support\_points()}) and at the quadrature points (\texttt{Particles::Generator::quadrature\_points()}) of a
+possibly non-matching triangulation. Consequently, complex particle patterns can be inserted
+using unstructured grids generated outside of \dealii{}.
To visualize the motion of particles, the \texttt{Particles::DataOut} class was added to the library.
-In its current version, this class supports writing the particles positions and id in all format supported
-by \dealii, but does not allow writing the properties attached to the particles.
\texttt{MatrixFree::cell\_loop()}, to schedule operations on sections of vectors close
to the matrix-vector product to increase data locality.
-\item \texttt{step-69} presents a first-order scheme solving compressible
-Euler's equations of gas dynamics with a graph-viscosity stabilization
-technique. Beside the usual conservation properties of mass, momentum and
+\item \texttt{step-69} presents a first-order scheme solving the compressible
+Euler equations of gas dynamics with a graph-viscosity stabilization
+technique. Beside the usual conservation properties of mass, momentum, and
total energy, the method also guarantees that the constructed solution
-obeys pointwise stability constraints (positivity of density, internal
-energy and a local minimum principle on the specific entropy). As such
+obeys pointwise stability constraints (in particular positivity of
+density and internal
+energy, and a local minimum principle on the specific entropy). As such
\text{step-69} is strictly speaking more a collocation-type discretization
than a variational formulation, even though it is implemented with finite
elements.
that depends (nonlinearly) on information from the previous time-step that
spans more than one cell. Therefore, assembly loops operate directly on the
sparsity graph in order to retrieve information from the entire stencil
-associated to each node. From a programming perspective, \texttt{step-69}
+associated with each node. From a programming perspective, \texttt{step-69}
features a number of techniques that are of interest for a wider audience:
It discusses a hybrid thread and MPI parallelized scheme with efficient
-(MPI node) local numbering of degrees of freedom. It showcases how to
+MPI node-local numbering of degrees of freedom. It showcases how to
perform asynchronous write-out of results using a background thread with
\texttt{std::async}, and discusses a simple but effective checkpointing and
restart technique.
projects / release-papers.git / commitdiff