Ice

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Reporter Hsieh, Tsung-Lin
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Question

• A wire with weights attached to each end is
  placed across a block of ice.
• The wire may pass through the ice without cutting
  it.
• Investigate the phenomenon.

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Outline

• Experimental setup
• Typical results
• Hypothesis
• Pressure effect
• Weight
• Thermal conductivity
• Curvature
• Other effect
• Summary

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Experimental Setup
Ice
Camera
Weights
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Typical Result

• The wire position is obtained by MATLAB program.

Duration 1 hr
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Pressure Effect

• Ice under the wire tends to melt.

Heat
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Schematic Phase Diagram
Pressure
Liquid
Atmospheric pressure
Ice
Solid
Gas
Temperature
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Schematic Phase Diagram
Pressure
IceWater
Absorbing heat
Cutting
Liquid
Atmospheric pressure
Solid
Gas
Temperature
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Schematic Phase Diagram
Pressure
Releasing heat
Liquid
Atmospheric pressure
Ice
Solid
Gas
Temperature
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Pressure effect

• Weight
• Thermal conductivity
• Curvature

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Speed at Center

• Speed of the center of the wire after it sinks
  into the ice.

distance
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Weight
Stainless steel wire 0.4mm

• 3kg 0.11
• 4kg 0.18
• 5kg 0.26
• 6kg 0.30
• 7kg 0.39
• 8kg 0.49
• (cm/min)?

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Weight vs. Speed at Center
Stainless steel wire 0.4mm
Pressure
l
s
g
Temperature
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Mathematical Estimation

• Heat conducting rate
• From Clausius-Clapeyron equation,
• Center speed upper limit
• Pressure effect plays an important role.

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(No Transcript)
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Material vs. Speed at Center

• Thermal Conductivity
• (W/m-K)?
• Aluminum 235
• Steel 16.3

speed 0.34 cm/min
speed 0.30 cm/min

• Good thermal conductor cuts faster.

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Water Flow Video
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Wire Diameter

• 0.3mm 0.30
• 0.4mm 0.18
• 0.6mm 0.06 (cm/min)?

• Explanation...

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Pressure and Curvature
T
T
?
?
r
?
?
d
Cross-section of the Wire
Ice
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Cutting Speed

• After the whole wire sinks into the ice

Pressure effect dominates
External heat input is more significant
Left side
center
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External Heat Effect

• Water melts due to external heat input
• It can solidify again because the temperature
  inside the ice is below 00C (-150C -0.60C).

Hot
Cold
External heat
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Summary

• The wire passes through the ice
• Pressure effect
• External heat effect
• The ice regelates (without being cut)
• Pressure releases
• Temperature inside the ice is below 00C

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Thank you for your attention.
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Ambient Temperature

• The speed at center is almost constant.
• Repeatable in different temperature (230C280C).
• Ambient heat can be neglected.

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Weight

• 6kg 0.12
• 4kg 0.06
• 3kg 0.05
• (cm/min)?

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(No Transcript)
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Temperature inside the Ice
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Time interval 5 min
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Time interval 5 min
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Curvature vs. Speed

• At the Beginning of Cutting

Pressure effect dominates
Left side
center
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Patterns formed on regelated ice
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Problems on the Hypothesis

• Water can be supercooled and it dont have to
  follow the phase line.
• Of course not, but the final state is, as
  observed.
• The direction of pressure
• The cross-section shape of the wire
• The surface property (roughness) of the wire
• It takes some time for it to travel along the
  phase line.
• In our case, it is a good assumption.
• Heat may flow to not only the ice below it.
• There may be water flow.
• My position error? Less than 5
• What about put the ice in 00C?
• Wire moving causes cutting, not only pressing.
• Does your wire has the same diameter after
  hanging weights?
• PICK UP the main physics

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Speed v.s. Curvature at time 1

• In the middle of the ice, speed is positively
  related to the curvature.
• The speed is faster at both side because of
  external heat.

Fig. Acceleration
Fig. Speed of the whole wire
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Speed v.s. Curvature at time 2

• In the middle of the ice, speed is positively
  related to the curvature.
• The speed is faster at both side because of
  external heat.

Fig. Speed of the whole wire
Fig. Acceleration