From fd2fff1ccfe0ebe96fd8d219efb5e5123840b31a Mon Sep 17 00:00:00 2001 From: Wolfgang Bangerth Date: Sun, 31 May 2020 18:25:57 -0600 Subject: [PATCH] Minor edits. --- 9.2/paper.tex | 60 +++++++++++++++++++++++++-------------------------- 1 file changed, 30 insertions(+), 30 deletions(-) diff --git a/9.2/paper.tex b/9.2/paper.tex index dee593d..ff2c0a2 100644 --- a/9.2/paper.tex +++ b/9.2/paper.tex @@ -281,17 +281,17 @@ that we briefly outline in the remainder of this section: 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. @@ -610,30 +610,29 @@ Fourier coefficients \cite{BangerthKayserHerold2007} and Legendre coefficients \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. @@ -920,12 +919,13 @@ pre and post operations, which can be passed to \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. @@ -934,10 +934,10 @@ The time-update at each node requires the evaluation of a right-hand side 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. -- 2.39.5