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Temperature fluctuations in a convection cell with rough upper and lower surfaces
Summary
Rough surfaces in turbulent convection enhance heat transport by altering local boundary dynamics. This study found increased temperature fluctuations and similar thermal dissipation mechanisms in rough versus smooth cells.
Area of Science:
- Physics
- Fluid Dynamics
- Thermodynamics
Background:
- Turbulent convection is crucial in various natural and industrial processes.
- Surface roughness significantly impacts heat transfer and fluid dynamics.
- Understanding boundary effects is key to controlling convective heat transport.
Purpose of the Study:
- To investigate the effect of surface roughness on turbulent convection.
- To analyze temperature statistics, power spectrum, and thermal dissipation.
- To determine the mechanism behind enhanced heat transport in rough cells.
Main Methods:
- Experimental setup: turbulent convection in a cell with rough and smooth surfaces.
- Measurements: temperature statistics, frequency power spectrum, thermal dissipation.
- Analysis: comparison of results between smooth and rough cells across varying Rayleigh numbers.
Main Results:
- Rough surfaces increased temperature fluctuation width by ~25% and uniformly across the frequency range.
- Thermal dissipation, characterized by cutoff frequency and temperature derivative, showed similar mechanisms in both cell types.
- Enhanced heat transport in rough cells is primarily driven by local boundary dynamics.
Conclusions:
- Surface roughness modifies temperature fluctuations but not the fundamental thermal dissipation mechanism in turbulent convection.
- Local dynamics at the boundaries are the main drivers of enhanced heat transport in rough cells.
- Findings provide insights into optimizing heat transfer in systems with rough surfaces.