quadgrid - a simple c++ library for particles in a cartesian quad grid

This library provides simple (template) classes that for a useful starting point for the implementation of MPM/PIC methods

License

Most of the code is ditributed under a permissive BSD-2-Clause license. As an exception the GNU Octave interface, which links to GNU Octave libraries is under a GPL (v3 or later) copyleft license.

Contents

The repository consists of the following folders :

• include contains headers (.h) and template method definition files (`_imp.h`) the main files included are
  • quadgrid_cpp.h including the declaration of the (template) class quadgrid_t representing the quad grid
  • quadgrid_cpp_imp.h contains out-of-line definitions for template methods of the quadgrid_t class
  • particles.h declares the particles_t clares representing particles embedded in a quadgrid_t grid
• src contains implementation of methods in the above classes that do not depend on template parameters
• test provides a few tests and examples
• octave provides a draft of an interface for accessing qudtree objects from within the GNU Octave interpreter, which consists of
  • quadgrid.h defining the quadgrid class inheriting from octave_base_value
  • quadgrid.cc defines two Octave functions quadgrid and quadgrid_loopaccessible from the interpreter

Building the examples

To build the examples move to the test directory and run

mpicxx -std=c++17 -I../include -o particle_sort_example particle_sort_example.cpp ../src/particles.cpp

Main methods in the particles_t class

• particles_t::p2g implements transfer of quantities from the particles to the grid according to the formula

$$ u_i = \sum_p N_i(x_p) U_p $$

• particles_t::g2p implements transfer of quantities from the particles to the grid according to the formula

$$ U_p = \sum_i N_i(x_p) u_i
$$