Water Drops

Collide

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Fig. 15. Coalescence at V = 45.5 cm/sec, angle 0 degrees.

Fig. 16. Direct coalescence collisions at V = 102 cm/sec.

Fig. 17. Most direct glancing rebound collision recorded at V = 102 cm/sec, angle 32 degrees.

Fig. 17. Most direct glancing rebound collision recorded at V = 102 cm/sec, angle 32 degrees.

Fig. 18. Direct reflex disjection at onset conditions, V = 137 cm/sec.

Fig. 19. Early stages of direct reflex disjection at V = 166 cm/sec.

Fig. 20. Reflex disjection at V = 154 cm/sec, angle 1 degree. (See Fig. 19 for early stages.)

Fig. 21. Most direct coalescence collision recorded at V = 154 cm/sec, angle 11 degrees.

Fig. 22. Delayed disruption at V = 154 cm/sec, angle 24 degrees.

Fig. 23. Disruption at V= 154 cm/sec, angle 37.5 degrees.

Fig. 23. Disruption at V= 154 cm/sec, angle 37.5 degrees.

Fig. 24. Indirect coalescence collisions at V = 166 cm/sec.

Fig. 25. Disruption at V = 166 cm/sec.

Fig. 26. More direct disruption at V = 166 cm/sec.

Fig. 27. Glancing rebound at V = 166 cm/sec.

Fig. 25. Disruption at V = 166 cm/sec.

Fig. 26. More direct disruption at V = 166 cm/sec.

Fig. 27. Glancing rebound at V = 166 cm/sec.

Fig. 28. Direct reflex disjection at V = 331 cm/sec. (Separation step not recorded.)

Fig. 29. Out-of-plane reflex disjection at V = 331 cm/sec.

Fig. 30. Indirect coalescence collisions at V = 331 cm/sec.

Fig. 31. Disruption at V = 331 cm/sec.

Fig. 31. Disruption at V = 331 cm/sec.

Fig. 32. Least direct coalescence collision recorded at V = 63 cm/sec, angle 79
degrees.

Fig. 33. Glancing rebound at V = 160 cm/sec, angle 50 degrees.

Fig. 33. Glancing rebound at V = 160 cm/sec, angle 50 degrees.

Fig. 34. Direct reflex disjection at V = 266 cm/sec. (Compare with Fig. 18.)

Fig. 35. Most direct coalescence collision recorded at V = 266 cm/sec, angle 6
degrees.

Fig. 36. Less direct coalescence collisions at V = 266 cm/sec.

Fig. 36. Less direct coalescence collisions at V = 266 cm/sec.

Fig. 37. Disruption at V = 266 cm/sec.

Fig. 38. Glancing rebound at V = 266 cm/sec.

Fig. 39. Direct reflex disjection at V = 607 cm/sec.

Fig. 40. Indirect reflex disjection at V = 607 cm/sec.

Fig. 40. Indirect reflex disjection at V = 607 cm/sec.

Fig. 41. Most direct coalescence collision recorded at V = 607 cm/sec, angle 12
degrees.

Fig. 42. Delayed disruption at V = 607 cm/sec, angle 18.5 degrees.

Fig. 43. Disruption at V = 607 cm/sec, angle 19 degrees.

Fig. 44. Direct reflex disjection at V = 705 cm/sec.

Fig. 44. Direct reflex disjection at V = 705 cm/sec.

Fig. 45. Direct rebound at V = 61 cm/sec, angle 2 degrees.

Fig. 46. Rebound (left) and coalescence (right) at V = 86 cm/sec, angle 17 degrees.

Fig. 47. Coalescence at V = 168 cm/sec, angle 2 degrees.

Fig. 48. Direct coalescence at V = 168 cm/sec.

Fig. 49. Indirect coalescence at V = 168 cm/sec.

Fig. 50. Glancing rebound at V = 168 cm/sec.

Fig. 48. Direct coalescence at V = 168 cm/sec.

Fig. 49. Indirect coalescence at V = 168 cm/sec.

Fig. 50. Glancing rebound at V = 168 cm/sec.

Fig. 51. Coalescence at V = 230 cm/sec, angle 1 degree.

Fig. 52. Late stages of direct reflex disjection at onset conditions, V = 244 cm/sec.

Fig. 52. Late stages of direct reflex disjection at onset conditions, V = 244 cm/sec.

Fig. 53. Reflex disjection at V = 273 cm/sec, angle 0 degrees.

Fig. 54. Direct reflex disjection at V = 273 cm/sec.

Fig. 54. Direct reflex disjection at V = 273 cm/sec.

Fig. 55. Most direct coalescence collision recorded at V = 273 cm/sec, angle 5
degrees.

Fig. 56. Least direct coalescence collision found at V = 273 cm/sec, angle 29
degrees.

Fig. 57. Indirect coalescence at V = 273 cm/sec.

Fig. 58. Direct reflex-disjection stages at V = 451 cm/sec.

Fig. 59. Disruption at V = 451 cm/sec.

Fig. 57. Indirect coalescence at V = 273 cm/sec.

Fig. 58. Direct reflex-disjection stages at V = 451 cm/sec.

Fig. 59. Disruption at V = 451 cm/sec.

Fig. 60. Reflex disjection at V = 451 cm/sec, angle 1 degree. (Separation not
recorded.)

Fig. 61. Coalescence at V = 33 cm/sec.

Fig. 62. Coalescence at V = 103 cm/sec, angle 0 degrees.

Fig. 63. Delayed coalescence at V = 103 cm/sec, angle 60 degrees.

Fig. 64. Least direct coalescence collision recorded at V = 103 cm/sec, angle 72 degrees.

Fig. 64. Least direct coalescence collision recorded at V = 103 cm/sec, angle 72 degrees.

Fig. 65. Glancing rebound at V = 152 cm/sec, angle 53 degrees (upper row) and
angle 58 degrees (lower row).

Fig. 66. Disruption at V = 280 cm/sec, angle 52 degrees.

Fig. 67. Direct coalescence collisions at V = 384 cm/sec.

Fig. 66. Disruption at V = 280 cm/sec, angle 52 degrees.

Fig. 67. Direct coalescence collisions at V = 384 cm/sec.

Fig. 68. Direct reflex disjection at V = c. 720 cm/sec.

Fig. 69. Indirect reflex disjection at V = c. 720 cm/sec.

Fig. 70. Stages of more direct disruption at V = c. 720 cm/sec.

Fig. 71. Less direct disruption at V = c. 720 cm/sec.

Fig. 72. Partial coalescence at V = 43 cm/sec.

Fig. 73. Rebound at V = 47 cm/sec.

Fig. 74. Rebound and coalescence at V = 55 cm/sec.

Fig. 75. Partial coalescence at angle 48 degrees and rebound at angle 52 degrees with V = 47 cm/sec.

Fig. 73. Rebound at V = 47 cm/sec.

Fig. 74. Rebound and coalescence at V = 55 cm/sec.

Fig. 75. Partial coalescence at angle 48 degrees and rebound at angle 52 degrees with V = 47 cm/sec.

Fig. 76. Coalescence at V = 131 cm/sec.

Fig. 77. Glancing rebound at V = 131 cm/sec.

Fig. 78. Coalescence at V = 339 cm/sec, angle 1 degree.

Fig. 77. Glancing rebound at V = 131 cm/sec.

Fig. 78. Coalescence at V = 339 cm/sec, angle 1 degree.

Fig. 79. Coalescence at V = 339 cm/sec, angle 24 degrees.

Fig. 80. Direct coalescence collisions at V = 517 cm/sec.

Fig. 80. Direct coalescence collisions at V = 517 cm/sec.

Fig. 81. Coalescence with capture of bubble at V = 517 cm/sec, angle 0 degrees.

Fig. 82. Indirect coalescence at V = 517 cm/sec.

Fig. 83. Relatively direct disruption at V = 517 cm/sec.

Fig. 84. Disruption at V = 517 cm/sec.

Fig. 83. Relatively direct disruption at V = 517 cm/sec.

Fig. 84. Disruption at V = 517 cm/sec.

Fig. 85. Coalescence at V = 47 cm/sec.

Fig. 86. Coalescence at V = 67 cm/sec, angle 65 degrees.

Fig. 86. Coalescence at V = 67 cm/sec, angle 65 degrees.

Fig. 87. Partial coalescence with delayed bridging at V = 139 cm/sec, angle 51
degrees.

Fig. 88. Two cases of glancing rebound at angle 68 degrees (first row) and angle 71 degrees (second row) with V = 139 cm/sec.

Fig. 88. Two cases of glancing rebound at angle 68 degrees (first row) and angle 71 degrees (second row) with V = 139 cm/sec.

Fig. 89. Coalescence at V = 303 cm/sec, angle 1 degree.

Fig. 90. Disruption at angle 54 degrees and coalescence at angle 20 degrees with V = 303 cm/sec.

Fig. 90. Disruption at angle 54 degrees and coalescence at angle 20 degrees with V = 303 cm/sec.

Fig. 91. Direct rebound of 913- and 631-micron drops at V = 36 cm/sec.

Fig. 92. Coalescence of 913- and 631-micron drops at V = 36 cm/sec.

Fig. 93. Partial coalescence of 344-micron drops with 1160-micron drops at V = 48.5 cm/sec.

Fig. 94. Direct partial coalescence of 415-micron drops with 1175-micron drops at V = 56 cm/sec.

Fig. 92. Coalescence of 913- and 631-micron drops at V = 36 cm/sec.

Fig. 93. Partial coalescence of 344-micron drops with 1160-micron drops at V = 48.5 cm/sec.

Fig. 94. Direct partial coalescence of 415-micron drops with 1175-micron drops at V = 56 cm/sec.

Fig. 95. Spatter with drops of 1630 and 1080 microns colliding at V = 558 cm/sec.

Fig. 96. Disruption of 1630- and 1080-micron drops at V = 558 cm/sec.

Fig. 97. Impact of 1640-micron drops with a water surface at V = c. 425 cm/sec.

Fig. 98. Impact of 1660-micron drops with a film of water on a smooth glass plate at V > 520 cm/sec.

Fig. 98. Impact of 1660-micron drops with a film of water on a smooth glass plate at V > 520 cm/sec.

The unpublished photographs displayed here are contained in my
dissertation, "**Behavior of Water Drops Colliding in Humid Nitrogen**", submitted in partial
fulfillment of the requirements for the degree of Doctor of Philosophy (Chemical Engineering)
at the University of Wisconsin, 1970.

"V" is the relative velocity between the drops before collision. The note which appears when your cursor is
moved over a photo page identifies which frames were recorded using still photography. All other frames were
selected from high speed motion pictures. The quantitative research focused on collisions between pairs of drops
with diameters in the following six size groups:

Figs. 32 - 44 0.20 + 0.20 mm

Figs. 45 - 60 0.90 + 0.45 mm

Figs. 61 - 71 0.40 + 0.20 mm

Figs. 72 - 84 0.90 + 0.30 mm

Figs. 85 - 90 0.45 + 0.15 mm

An article explaining the equipment used in this research, *A Device for producing controlled collisions
between pairs of drops,* was published by R. W. Park & E. J. Crosby in *
Chemical Engineering Science,* 1965 **20** 39-45. A copy of the dissertation is available at
the main library of the University of Wisconsin-Madison.