Dynamics of single bubble between a moving spherical boundary and a plate structure

Physics of Fluids, Journal Year: 2025, Volume and Issue: 37(1)

Published: Jan. 1, 2025

Boundary conditions significantly influence the near-field dynamics of bubbles. This study employs numerical simulations to investigate coupling characteristics high-pressure bubbles near solid boundaries and moving spherical boundaries. It focuses on effects sinking velocity sphere initial bubble–boundary distance bubble evolution loading characteristics. The results indicate that an increase in sphere's or a decrease leads tearing during collapse process. generates high-speed water jets directed either toward center boundary, reducing kinetic energy sphere. shock waves caused by temporarily impede motion, while lagging flow induced expansion contraction has relatively minor impact. As increases, phenomenon gradually weakens may even disappear. attenuation is attributed suppression Bjerknes effect which reduces tendency migrate boundary. Furthermore, intensity affects pressure distribution region around Strong induces double-peaked profile, weak single-peaked profile primarily dominated collapse. reveals critical interactions motion distribution, providing valuable insights for engineering design applications related fields.

Language: Английский

Numerical Investigation of Symmetrical and Asymmetrical Characteristics of a Preloading Spiral Case and Concrete during Load Rejection

Symmetry, Journal Year: 2024, Volume and Issue: 16(10), P. 1277 - 1277

Published: Sept. 27, 2024

During the transient process of load rejection, hydraulic pressure applied to pump-turbine and plant concrete changes dramatically induces high dynamic stress on spiral case. The preloading case has been widely used in large-scale pumped-storage power stations due its excellent load-bearing capacity. However, studies impact structural response during rejection are still few number. In this paper, 3D flow domain models a prototype designed analyze characteristics flow-induced behavior steel under different pressures rejection. results show that asymmetric design logarithmic lines ensures an axially symmetric potential within with uniform distribution. Higher provides larger clearance, leading greater deformation stress, their maximum values located at mandoor inner edge, respectively. combined effect asymmetrical shape, internal unbalanced force leads clearance distribution, resulting distribution along axial direction but symmetrical characteristic near waistline response. Stress variations sections between share similar It follows same trend as lower pressures, while there is delayed peak contact phenomenon when reaches static head. conclusions provide scientific guidance for optimizing selection stable operation units.

Language: Английский