How-to: create a samurai field

Before creating a samurai field, you have to create a mesh. If you don’t know how to create a mesh, please refer to the mesh how-to guide here.

A samurai field is a data structure that allows you to store and manipulate data on a samurai mesh. Fields can be defined on different mesh types, such as uniform meshes, multi-resolution meshes, and adaptive meshes.

Two types of fields are available in samurai:

• scalar fields: Fields that store a single value per cell.

• vector fields: Fields that store multiple values per cell (e.g., a vector with several components).

Creating a scalar field

To create a scalar field, you can use the make_scalar_field function. Here is a simple example of creating a scalar field on a multi-resolution mesh:

#include <samurai/box.hpp>
#include <samurai/field.hpp>
#include <samurai/mr/mesh.hpp>

int main()
{
    static constexpr std::size_t dim = 2;

    samurai::Box<double, dim> box({0.0, 0.0}, {1.0, 1.0});

    auto config = samurai::mesh_config<dim>().min_level(2).max_level(5);
    auto mesh   = samurai::mra::make_mesh(box, config);

    auto field = samurai::make_scalar_field<double>("u", mesh);

    return 0;
}

In this example, we first create a 2D multi-resolution mesh over the box defined from \((0.0, 0.0)\) to \((1.0, 1.0)\) with a minimum refinement level of 2 and a maximum refinement level of 5. Then, we create a scalar field named “u” on the mesh using the make_scalar_field function. The type of the field values is specified as double. You can replace double with any other data type as needed.

Creating a vector field

To create a vector field, you can use the make_vector_field function. Here is a simple example of creating a vector field with 3 components on a multi-resolution mesh:

#include <samurai/box.hpp>
#include <samurai/field.hpp>
#include <samurai/mr/mesh.hpp>

int main()
{
    static constexpr std::size_t dim = 2;

    samurai::Box<double, dim> box({0.0, 0.0}, {1.0, 1.0});

    auto config = samurai::mesh_config<dim>().min_level(2).max_level(5);
    auto mesh   = samurai::mra::make_mesh(box, config);

    auto field = samurai::make_vector_field<double, 3>("v", mesh); // 3 components

    return 0;
}

In this example, we create a vector field named “v” with 3 components on the same multi-resolution mesh. The type of the field values is specified as double. You can replace double with any other data type as needed, and change the number of components by modifying the second template parameter.