Modelling frazil and anchor ice on submerged objects

Lasse Makkonen (Corresponding Author), Maria Tikanmäki

Research output: Contribution to journalArticleScientificpeer-review

2 Citations (Scopus)

Abstract

Frazil and anchor ice cause blockage of water intakes and icing of other type of submerged objects. In this paper, the physical mechanisms that control these phenomena are discussed and analyzed. Our conclusions are somewhat different from the views presented earlier. 1) Ice crystals in water may originate from microbubbles and turbulence, so that nucleation may occur regardless of an external source 2) The number concentration of ice crystals may not necessarily increase much during an active frazil ice event, 3) The heat transfer from a frazil ice crystal is controlled by its relative rise velocity, not by water turbulence, 4) The collision efficiency of frazil ice crystals on grid components is so small that frazil typically causes no blockage of submerged water intakes, and 5) Blockage is largely caused by ice platelets that grow in-situ on the structural components. We model frazil and anchor ice formation theoretically and find that the uncertainty about the concentration of ice crystals is the main obstacle to accurate modelling. Within these limits, our model results agree well with the available experimental data.

Original languageEnglish
Pages (from-to)64-74
Number of pages11
JournalCold Regions Science and Technology
Volume151
DOIs
Publication statusPublished - 1 Jul 2018
MoE publication typeA1 Journal article-refereed

Fingerprint

ice crystal
Anchors
anchor
Ice
ice
modeling
Crystals
turbulence
water
structural component
Water
nucleation
Turbulence
heat transfer
collision
Platelets
Nucleation
Heat transfer

Keywords

  • Anchor ice
  • Frazil
  • Frazil ice
  • Ice
  • Nucleation
  • Supercooling
  • Water intake

Cite this

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title = "Modelling frazil and anchor ice on submerged objects",
abstract = "Frazil and anchor ice cause blockage of water intakes and icing of other type of submerged objects. In this paper, the physical mechanisms that control these phenomena are discussed and analyzed. Our conclusions are somewhat different from the views presented earlier. 1) Ice crystals in water may originate from microbubbles and turbulence, so that nucleation may occur regardless of an external source 2) The number concentration of ice crystals may not necessarily increase much during an active frazil ice event, 3) The heat transfer from a frazil ice crystal is controlled by its relative rise velocity, not by water turbulence, 4) The collision efficiency of frazil ice crystals on grid components is so small that frazil typically causes no blockage of submerged water intakes, and 5) Blockage is largely caused by ice platelets that grow in-situ on the structural components. We model frazil and anchor ice formation theoretically and find that the uncertainty about the concentration of ice crystals is the main obstacle to accurate modelling. Within these limits, our model results agree well with the available experimental data.",
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Modelling frazil and anchor ice on submerged objects. / Makkonen, Lasse (Corresponding Author); Tikanmäki, Maria.

In: Cold Regions Science and Technology, Vol. 151, 01.07.2018, p. 64-74.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Modelling frazil and anchor ice on submerged objects

AU - Makkonen, Lasse

AU - Tikanmäki, Maria

PY - 2018/7/1

Y1 - 2018/7/1

N2 - Frazil and anchor ice cause blockage of water intakes and icing of other type of submerged objects. In this paper, the physical mechanisms that control these phenomena are discussed and analyzed. Our conclusions are somewhat different from the views presented earlier. 1) Ice crystals in water may originate from microbubbles and turbulence, so that nucleation may occur regardless of an external source 2) The number concentration of ice crystals may not necessarily increase much during an active frazil ice event, 3) The heat transfer from a frazil ice crystal is controlled by its relative rise velocity, not by water turbulence, 4) The collision efficiency of frazil ice crystals on grid components is so small that frazil typically causes no blockage of submerged water intakes, and 5) Blockage is largely caused by ice platelets that grow in-situ on the structural components. We model frazil and anchor ice formation theoretically and find that the uncertainty about the concentration of ice crystals is the main obstacle to accurate modelling. Within these limits, our model results agree well with the available experimental data.

AB - Frazil and anchor ice cause blockage of water intakes and icing of other type of submerged objects. In this paper, the physical mechanisms that control these phenomena are discussed and analyzed. Our conclusions are somewhat different from the views presented earlier. 1) Ice crystals in water may originate from microbubbles and turbulence, so that nucleation may occur regardless of an external source 2) The number concentration of ice crystals may not necessarily increase much during an active frazil ice event, 3) The heat transfer from a frazil ice crystal is controlled by its relative rise velocity, not by water turbulence, 4) The collision efficiency of frazil ice crystals on grid components is so small that frazil typically causes no blockage of submerged water intakes, and 5) Blockage is largely caused by ice platelets that grow in-situ on the structural components. We model frazil and anchor ice formation theoretically and find that the uncertainty about the concentration of ice crystals is the main obstacle to accurate modelling. Within these limits, our model results agree well with the available experimental data.

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KW - Frazil

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KW - Nucleation

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KW - Water intake

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