GfsOutputPPM

From Gerris

OutputPPM writes a colour image of the given scalar field in PPM (Portable PixMap) format.

The syntax in parameter files is:

[ GfsOutputScalar ]

By default the pixels are the square cells at the highest level of refinement. The level of the cells displayed can be controlled using the maxlevel option of GfsOutputScalar. Setting maxlevel can also be useful to control the size (in pixels) of the image produced: when maxlevel is set the pixel size of the image will always be a multiple (depending on the number of boxes in the computation domain) of 2^maxlevel. This holds even when the number of levels in the simulation changes due to adaptive refinement (see also this question in the FAQ).

The NODATA keyword of GfsFunction can be used to mask out parts of the domain. For example drawing only the positive values of the pressure could be written:

OutputPPM { start = end } end.ppm { v = (P > 0 ? P : NODATA) }

The "no data" areas are drawn in black.

Note that this object is only available for 2D simulations.

Examples

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

  OutputPPM { istep = 2 } { ppm2mpeg > vort.mpg } {
    min = -10 max = 10 v = Vorticity 
  }

  OutputPPM { istep = 2 } { ppm2mpeg > t.mpg } {
    min = 0 max = 1 v = T
  }

  OutputPPM { start = 15 } { convert -colors 256 ppm:- vort.eps } {
    min = -10 max = 10 v = Vorticity
  }

  OutputPPM { start = 15 } { convert -colors 256 ppm:- t.eps } {
    min = 0 max = 1 v = T
  }

• Vortex street around a "heated" cylinder

  OutputPPM { istep = 2 } { ppm2mpeg > t.mpg } {
    min = 0 max = 0.4 v = T
  }

  OutputPPM { start = 15 } { convert -colors 256 ppm:- t.eps } {
    min = 0 max = 0.4 v = T
  }

• Rayleigh-Taylor instability

  OutputPPM { istep = 2 } { ppm2mpeg > vort.mpg} {
    min = -30 max = 30 v = Vorticity
  }

  OutputPPM { istep = 2 } { ppm2mpeg > t.mpg } {
    min = 0 max = 1 v = T
  }

  OutputPPM { start = end } { convert -colors 256 ppm:- vort.eps } {
    min = -30 max = 30 v = Vorticity
  }

  OutputPPM { start = end } { convert -colors 256 ppm:- t.eps } {
    min = 0 max = 1 v = T
  }

• Coalescence of a pair of Gaussian vortices (Gerris logo)

    OutputPPM { istep = 2 } { ppm2mpeg > logo.mpg } {
        v = Vorticity
        min = -0.1348 max = 6.22219
        # Only generate the movie in a small box centered on the
	# origin. We also need to make sure that box size is a multiple
	# of 1./64. so that the PPM image size stays constant (ffmpeg
	# crashes on variable image sizes).
        condition = (Level < 6 || 
                     (x >= -3./128. && x <= 3./128. && y >= -3./128. && y <= 3./128.))
    }

• The 2004 Indian Ocean tsunami

    OutputPPM { step = 60 } { ppm2mpeg > velocity.mpg } {
	maxlevel = 10
	v = Velocity 
	min = 0 max = 0.25
    }

    OutputPPM { step = 60 } { ppm2mpeg > zb.mpg } {
	maxlevel = 10
	v = Zb
    }

• "Garden sprinkler effect" in wave model

    OutputPPM { step = 12 } { ppm2mpeg > hs-MINLEVEL-NTHETA.mpg } { v = Hs maxlevel = 7 }

• Cyclone-generated wave field

    OutputPPM { istep = 1 } { ppm2mpeg > hs.mpg } { v = Hs maxlevel = 9 }

    OutputPPM { istep = 1 } { ppm2mpeg > level.mpg } { v = Level min = 4 max = LEVEL maxlevel = 9 }

• Time-reversed VOF advection in a shear flow

    OutputPPM { start = 0 } { convert ppm:- t-0.eps } { v = T }

    OutputPPM { start = 2.5 } { convert ppm:- t-2.5.eps } { v = T }

    OutputPPM { start = 5 } { convert ppm:- t-5.eps } { v = T }

    OutputPPM { start = end } { convert ppm:- dt-5.eps } { v = DT }

• Time-reversed advection with curvature-based refinement

    OutputPPM { start = end } { convert ppm:- dt-5.eps } { v = DT }

• Lid-driven cavity at Re=1000

  OutputPPM { start = end } { convert -colors 256 ppm:- velocity.eps } {
    v = Velocity
  }

• Lid-driven cavity at Re=1000 (explicit scheme)

  OutputPPM { start = end } { convert -colors 256 ppm:- velocity.eps } {
    v = Velocity
  }

• Lid-driven cavity on an anisotropic mesh

  OutputPPM { start = end } { convert -colors 256 ppm:- -resize 128x128! velocity.eps } {
    v = Velocity
  }

• Gravity waves in a realistic ocean basin

    OutputPPM { start = 2 } { convert ppm:- p.eps } { v = P min = -5e-3 max = 5e-3 }