Slope limiter¶
Slope limiters are needed to combat nonlinear convective instabilities when jumps or shocks are present in the solution or coefficients. Ocellaris uses a special velocity slope limiting procedure to stabilise the momentum equation, see 1 for details.

method
The method employed to perform the slope limiting
Scalar methods:
None
OnlyBound
HierarchicalTaylor
Velocity methods:
Componentwise
Solenoidal (not ported to FEniCS 2018.1)
Default value: None

enforce_bounds
Take the min and max of the initial scalar field and clamp all subsequent solutions to be within these global bounds. Default value: off.

skip_boundaries
A list of boundary names to skip, cells sharing a facet with these boundaries are not limited. Default value:
[]
.

plot
Plot some information about the limiter. How much “wigglyness” is detected etc. Mostly for debug pruposes. Default value: off.

use_cpp
Use the C++ implementation and not the Python implementation if both exist. Default value: on.
Options for the HierarchicalTaylor limiter¶

enforce_bcs
Use the Dirichlet boundary conditions for the field in the limiter, not only to set the “safe range” of values, but also to clamp the boundary values directly to the BC values in the limiter. Default value: on.

use_weak_bcs
Trust the solution at the Dirichlet boundaries. The weak Dirichlet BCs may have kept the solution at the boundary from blowing up. Use the solution instead of the user specified Dirichlet value. Default value: on.

trust_robin_dval
The solution is expected to be close to the Robin BC dval value, so trust this value and use it to extend the “safe range” of values for vertices at the Robin boundary. Default value: on.
Options for velocity field limiters¶

comp_method
Only relevant for
Componentwise
limiter. Select which scalar limiter to use for the velocity components. Default value: None.

limit_conv
Limit the convecting velocity. Default value: off.
Citations
 1
Tormod Landet, KentAndre Mardal, and Mikael Mortensen. Slope limiting the velocity field in a discontinuous Galerkin divergencefree twophase flow solver. Computers and Fluids, 2019. doi:10.1016/j.compfluid.2019.104322.