Composer Basic Settings

surface meshing tolerance: Determines the relative size at which small cells from a meshed geometry surface are dropped. Set to 1.0 for simulations that do not contain any geometries.

cfl number: If time step is set to zero, the time step is automatically calculated, and for EM simulations, is reduced proportionately with the cfl number. The cfl number is the ratio of time step to Courant limit.

time step: If set to a value that is non-zero, this will be used as the simulation time step. If set to zero, the time step is calculated for you based on a number of factors.

  • If it is an ES simulation without particles, the time step is set to 1.0.

particles: Whether or not to include particles in the simulation.

  • no particles

  • include particles: If particles are included in the simulation, the following two properties are used to help calculate the time step.

    estimated max electron density: an estimate of the maximum electron density for setting a default timestep

    estimated max electron temperature (eV): an estimate of the maximum electron temperature for setting a default timestep

    dump nodal fields:

    If True, the fields used to calculate particle pushes will be written to memory. If false, they will not. This can save hard disk space in large simulations.

    particle to field deposition:

    • standard Previously referred to as minimum noise, this corresponds to an areaWeighting deposition scheme and is used for most all cases and conserves particle momentum.

    • smoother momentum conserving Previously referred to as maximum stability, this corresponds to an esirk1st order deposition scheme.

    • energy conserving This uses the edge E and nodal B fields for the particle push. In this scheme, the field is interpolated from the edge electric field using the nearest grid point from the grid aligned with the field component (e.g. from the x-grid for Ex, and from y-grid for Ey). In 2D and 3D, the interpolation is first order from the orthogonal grids.

collisions framework: Collisions framework to be used in the

simulations.

  • no collisions

  • reduced: Reduced collisions framework. Also called the “Impact Collider” framework.

  • monte carlo: Legacy Monte-Carlo interactions from previous VSim versions.

  • reactions: Full featured particle and fluid interactions most commonly used.

    collision order:

    Either random, constant, or rotate. A random order will perform each collision in a random order, constant in the order specified, and rotate will move down the list of collisions, performing a new one first, each time. As each particle can only be involved in one collision per timestep this can affect simulation results.