Methane bubble rise velocities under deep-sea conditions Influence of initial shape deformation

Terminal bubble rise velocities play a major role in industrial and environmental applications and the investigation of the rise velocities in different material systems and under different process conditions is of increasing interest. With respect to deep-sea oil spills and natural gas seeps, the investigation of methane bubble rise velocities under high-pressure and low-temperature conditions is of importance. In this context, near and far-field models have been developed that use a group of correlations which is valid for contaminated systems. With these equations the velocities of bubbles and drops are calculated with the assumption of an immobilized particle interface, due to the existence of seawater and the possibility of hydrate formation. Experimental results under deep-sea conditions are very rare and often contradicting. To identify the physical processes which influence the rise behavior of methane bubbles under deep-sea conditions, laboratory experiments in a high-pressure vessel and under ambient conditions are conducted. Methane bubble rise velocities at 4 degrees C and 20 degrees C as well as 0.1 and 15.1 MPa are investigated in artificial seawater and demineralized water. Contrary to expectations, our experimental results under deep-sea conditions (4 degrees C, 15.1 MPa) show a brought distribution of the rise velocities for similar volume equivalent bubble diameters. (C) 2016 Elsevier B.V. All rights reserved.