Spatiotemporal dynamics of a buoyancy-driven turbulent fire

Area of Science:

• Fluid dynamics
• Combustion science
• Complex systems analysis

Background:

• Buoyancy-driven turbulent fires exhibit complex spatiotemporal dynamics.
• Understanding fire structure evolution and predictability is crucial for safety and modeling.
• Visibility graphs offer a method to analyze complex network structures in turbulent flows.

Purpose of the Study:

• To numerically investigate the spatiotemporal dynamics of buoyancy-driven turbulent fires.
• To analyze the transition from ordered to disordered structures using spatial horizontal visibility graphs.
• To determine the factors influencing structure formation and the predictability of flow velocity fluctuations.

Main Methods:

• Numerical simulation of buoyancy-driven turbulent fire.
• Analysis using spatial horizontal visibility graphs to quantify order and disorder.
• Examination of the gravitational (baroclinic torque) term's influence on structure formation.
• Entropy flow analysis to understand energy transfer between temperature and velocity fluctuations.
• Application of reservoir computing to assess predictability of flow velocity fluctuations.

Main Results:

• A significant transition from order to disorder in fire structures was observed via mean degree in visibility graphs.
• The gravitational term critically impacts order in the near field and disorder in the far field.
• Predominant entropy flow from temperature to flow velocity fluctuations occurs at the interface of combustion products and ambient air.
• Transfer entropy effectively measures the predictability of near-field flow velocity fluctuations.

Conclusions:

• The study elucidates the mechanisms governing turbulent fire structure dynamics and predictability.
• Gravitational effects and entropy flow are key factors in fire behavior.
• Reservoir computing, informed by transfer entropy, shows promise for predicting turbulent fire dynamics.