Still Pictures for cornstarch+water
drying experiments (Feb '99)

DRYING EXPERIMENTS FOR DIFFERENT DRYING

         RATES : crack24-crack50
         corn-starch + distilled water (final configurations after 1 week)

         Three samples with same thickness (same amount of water + starch).
         All pictures are taken for two different magnifications same camera opening and  focus.

Petri dish diameter is 10cm, magnified window is 3.6mm X 2.5mm

sample 1.  kept at 18 C without air current over it

 sample 2.  kept in an incubator with slightly opened door at T=35 C without air current over it.

 sample 3.  kept in a temperature stabilized box at T=36 C with strong air current over it

 

     IMPORTANT: both for the integral samples and magnified
                central part the camera position and openings were
                the same for the three different samples
 

DRYING EXPERIMENTS FOR DIFFERENT THICKNESSES

           six samples with different thicknesses, and same drying conditions
           all samples are recorded as integral and magnified central part. Scales are:

 
 

    sample 1.  thickness measurments: 12.10; 12.04; 11.9; 12.19; 12.12 (mm)
               average thickness: 12.07 mm

 
 

    sample 2.  thickness measurments: 7.93; 8.12; 7.90; 8.13; 7.77 (mm)
               average thickness: 7.97 mm

 

    sample 3.  thickness measurments: 4.73; 4.93; 5.01; 4.67; 4.61 (mm)
               average thickness: 4.79 mm

 

    sample 4.  thickness measurments: 2.58; 2.64; 2.39; 2.51; 2.86 (mm)
               average thickness: 2.596 mm

 

    sample 5.  thickness measurments: 1.46; 1.27; 1.22; 1.37; 1.29 (mm)
               average thickness: 1.322 mm

 

    sample 6.  thickness measurments: 0.26; 0.61; 0.55; 0.42; 0.39 (mm)
               average thickness: 0.446 mm

 
 

    IMPORTANT: both for the integral samples and magnified
                central part the camera position and openings were
                the same for the six different samples
 

COMPARISON WITH OTHER CRACK PATTERNS
 

• Mud cracks with random polygons is similar to those bounded by straight cracks, while cracks in SiO2 layer shows similarities to sample 5 above
  (source: http://mobydick.physics.utoronto.ca/):

      


• cm-scale lab experiment (Skjeltorp & Meakin) shows no straight cracks (yet?), while dried mud field shows short straight cracks bounding incomplete diffusive cracks
  (source: T. Vicsek's book Fractal Growth Phenomena, 2nd ed., World Scientific, 1992):




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Last updated October 1, 2002 ©KtL