GfsSourceDiffusion

From Gerris

GfsSourceDiffusion is used to add diffusion to a scalar tracer (representing, for example, temperature or concentration).

The syntax in parameter files is:

[ GfsSourceScalar ] [ GfsDiffusion ] Phi

where Phi is the optional name of an existing variable. If Phi is specified the equation solved is not a standard diffusion equation anymore but takes the form

∂_tV = ∇.μ∇Φ

(i.e. by default Phi = V).

GfsSourceDiffusion can also be used to set a viscosity source term on each Cartesian vector component of the velocity, however when the viscosity is non-uniform GfsSourceViscosity should be used instead.

Examples

• B\'enard--von K\'arm\'an Vortex Street for flow around a cylinder at Re=160

  SourceDiffusion {} U 0.00078125

  SourceDiffusion {} V 0.00078125

• Vortex street around a "heated" cylinder

  SourceDiffusion {} T 0.001

  SourceDiffusion {} U 0.00078125

  SourceDiffusion {} V 0.00078125

• Boussinesq flow generated by a heated cylinder

  SourceDiffusion T 0.0001

• Comparison between explicit and implicit diffusion schemes on concentration tracer

    SourceDiffusion T1 T/(T+1.e9*(1.-T)*(1.-T)) {beta = 1}

• Conservation of diffusive tracer

    SourceDiffusion T 1e-4 { beta = 0.5 }

• Boundary layer on a rotating disk

    SourceDiffusion W 0.2

• Lid-driven cavity at Re=1000

  SourceDiffusion {} U 1e-3

  SourceDiffusion {} V 1e-3

• Lid-driven cavity with a non-uniform metric

  SourceDiffusion U 1e-3

  SourceDiffusion V 1e-3

• Lid-driven cavity on an anisotropic mesh

  SourceDiffusion {} U 1e-3

  SourceDiffusion {} V 1e-3

• Planar capillary waves

  SourceDiffusion U 0.0182571749236

  SourceDiffusion V 0.0182571749236

• Fluids of different densities

  SourceDiffusion U 0.0182571749236

  SourceDiffusion V 0.0182571749236

• Pure gravity wave

  SourceDiffusion {} U 0.0182571749236

  SourceDiffusion {} V 0.0182571749236

• Creeping Couette flow between cylinders

    SourceDiffusion T 1

• Gouy-Chapman Debye layer

    SourceDiffusion Cpos 1.0

    SourceDiffusion Cneg 1.0