Thermodynamics of the inception and interactions of multiple laser-produced cavitation bubbles using the lattice Boltzmann method.

• A new method for cavitation bubble inception without the initialization of gas nuclei is proposed using the DDF thermal pseudo-potential lattice Boltzmann method. • The coalescence mode is divided into two modes with different final collapse behaviors: coalescence in the collapse stage and coalescence in the growth stage. • The double interaction of unequal bubbles is systemically investigated. • Multiple-bubble cluster collapse is investigated, and the toroidal shape of the outer layer bubble in the final collapse stage is realized. Understanding the thermodynamics associated with the inception and interactions of multiple cavitation bubbles is vital in developing deeper insights into the flow field and temperature properties of cavitation bubble clouds. This paper describes a double-distribution-function thermal lattice Boltzmann method for investigating the thermodynamics of multiple-bubble interactions, and proposes a new two-dimensional method for cavitation bubble inception without the initialization of gas nuclei. This approach is validated by simulating the evolution of a laser-produced bubble. The interaction between two vapor bubbles is simulated, and the hydrodynamics and thermodynamics of cavitation bubbles are systematically investigated. Both weak and strong interactions among bubbles of equal size are accurately reproduced. The coalescence mode is further categorized according to differences in the collapse behaviors: the remaining parts collapse away from each other for coalescence in the collapse stage, but collapse toward each other for coalescence in the growth stage. Interactions among bubbles of different sizes are also explored and the different morphologies for various interaction modes are reported. In the case of small distances between bubbles under the weak interaction regime, the smaller bubble is pushed away from the symmetry axis, leading to an initial decrease in collapse intensity and then an increase as the distance between the two bubbles increases. Finally, the thermodynamics of a bubble cluster are investigated. The hydrodynamic and thermodynamic processes in different regions of the cavitation bubble cluster are determined, and the toroidal shape in the final stage is reproduced. The results demonstrate that the proposed model accurately simulates the complex interactions among multiple cavitation bubbles. [ABSTRACT FROM AUTHOR]