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Updated: Jul 30, 2026
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Published on: January 16, 2018
Periodic explosions by positive feedback in a rising foam column
Summary
Aqueous foam columns can periodically explode due to temperature drops. This phenomenon is linked to the foam
Area of Science:
- Fluid dynamics
- Thermodynamics
- Materials science
Background:
- Aqueous foams exhibit temperature drops during adiabatic rising.
- Periodic explosions in foam columns are observed under specific conditions.
Purpose of the Study:
- To investigate the cause of periodic explosions in adiabatic aqueous foam columns.
- To elucidate the role of thermal coupling and surfactant concentration in foam instability.
Main Methods:
- Experimental observation of adiabatic foam columns.
- Analysis of thermal coupling between foam and enclosing glass.
- Investigation of surfactant concentration effects on foam thermal conductivity.
Main Results:
- Foam temperature drops during adiabatic ascent.
- Explosions are traced to thermal coupling between foam and glass.
- A positive feedback loop involving heat flow and thermal conductivity was identified in unbuffered foams.
- The heat-pipe effect in foam cells is influenced by surfactant density.
Conclusions:
- Periodic foam explosions are driven by a positive feedback mechanism.
- This mechanism involves thermal coupling, surfactant concentration, and the heat-pipe effect.
- The absence of micellar buffering is crucial for this instability.
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