GfsSourceDiffusionExplicit

From Gerris

GfsSourceDiffusionExplicit is the time-explicit version of GfsSourceDiffusion. Note that this means that the timestep will need to be smaller than the local diffusion timescale to ensure stability i.e.

Δt < Δx²/μ

where Δx is the mesh size and μ the diffusion coefficient. Depending on the problem this can be very restrictive and the stable time-implicit scheme of GfsDiffusion could be used instead.

The syntax in parameter files is:

[ GfsSourceDiffusion ]

Examples

• Comparison between the explicit and implicit diffusion schemes

    SourceDiffusionExplicit T 1

• Comparison between explicit and implicit diffusion schemes on concentration tracer

    SourceDiffusionExplicit C T/(T+1.e9*(1.-T)*(1.-T))

• Conservation of diffusive tracer

    SourceDiffusionExplicit Te 1e-4

• Relaxation of a charge bump

    SourceDiffusionExplicit Rhoe 1 Phi

• Charge relaxation in an axisymmetric insulated conducting column

    SourceDiffusionExplicit Rhoe K*T Phi

    SourceDiffusionExplicit C  K*T/(T+1.e9*(1.-T)) Phi

• Charge relaxation in a planar cross-section

    SourceDiffusionExplicit Rhoe K*T Phi

• Equilibrium of a droplet suspended in an electric field

    SourceDiffusionExplicit Rhoe F*((1. - T)+ R*T) Phi

• Gouy-Chapman Debye layer

    SourceDiffusionExplicit Cpos Cpos Phi

    SourceDiffusionExplicit  Cneg -Cneg Phi