No abstract

The dynamics of gas jets expelled into liquid are investigated utilizing Computational Fluid Dynamics (CFD). Results are analyzed with respect to changes in external liquid velocity and mass flow rate of the gaseous jet. In order categorize the complicated nature of the gas-fluid interactions coupled with the many physical dependencies, a flow-regime map is created. The majority of the regimes result in the formation of gaseous cavities encasing the jet, of which forms several cavity types. The internal flow structure of the categorized regimes are then studied with respect to the jet interactions with surrounding liquid and formed cavities. The results show major regions of recirculation and that the jet acts as a confined jet.

Computational Fluid Dynamics (CFD) is employed to study the fundamental aspects of the internal pressure within artificially ventilated, gaseous cavities in both twin- and toroidal-vortex closure modes. The results show that several pressure regions develop within the cavities, indicating that the common assumption that the cavity has a constant pressure breaks down when evaluated in high detail. The internal cavity pressure is evaluated using a probability density function (PDF). The resulting PDF plots show a clusters with multiple peaks. A mixture-of-Gaussians (MOG) method is employed to better understand the distributions of these peaks. These peaks are then mapped to the simulation results, where it is observed that these peaks correlate to distinct cavity regions (which vary depending on cavity type). Moreover, these varying pressure regions appear to align with cavity-radius growth and reduction and appear to be the driving force of the internal, circulatory flow. Lastly, the importance of these pressure regions are investigated with respect to predictions from semi-empirical theory of the cavity shape, showing a moderate impact depending on where the cavity is probed. Overall, these results provide physical insight into ventilated cavity flow behavior that is often ignored.

No abstract

No abstract