English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

This study investigates the effect of vibration on the flow structuretransitions in thermal vibrational convection (TVC) systems, which occur when afluid layer with a temperature gradient is excited by vibration. Directnumerical simulations of TVC in a two-dimensional enclosed square box wereperformed over a range of dimensionless vibration amplitudes $0.001 \le a \le0.3$ and angular frequencies $10^{2} \le \omega \le 10^{7}$, with a fixedPrandtl number of 4.38. The flow visualisation shows the transition behaviourof flow structure upon the varying frequency, characterising three distinctregimes, which are the periodic-circulation regime, columnar regime andcolumnar-broken regime. Different statistical properties are distinguished fromthe temperature and velocity fluctuations at the boundary layer and mid-height.Upon transition into the columnar regime, columnar thermal coherent structuresare formed, in contrast to the periodic oscillating circulation. These columnsare contributed by merging of thermal plumes near the boundary layer, and theresultant thermal updrafts remain at almost fixed lateral position, leading toa decrease in fluctuations. We further find that the critical point of thistransition can be described nicely by the vibrational Rayleigh number$Ra_\mathrm{vib}$. As the frequency continues to increase, entering theso-called columnar-broken regime, the columnar structures are broken, andeventually the flow state becomes a large-scale circulation, characterised by asudden increase in fluctuations. Finally, a phase diagram is constructed tosummarise the flow structure transition over a wide range of vibrationamplitude and frequency parameters.

Flow structure transition in thermal vibrational convection