Effects of surface tension on the Richtmyer-Meshkov instability in fully compressible and inviscid fluids

Tang, Kaitao; Mostert, Wouter; Fuster, Daniel; Deike, Luc

doi:10.1103/physrevfluids.6.113901

Cited by 3 publications

(2 citation statements)

References 47 publications

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“…The open-source scientific computation toolbox Basilisk (Popinet 2019) is used in this work to solve the two-phase nonlinear, incompressible, variable-density Navier-Stokes equations. A second-order accurate discretisation is applied in both space and time, and a geometric volume-of-fluid (VOF) method in a momentum-conserving formulation is used to maintain a sharp representation of the liquid-gas interface while minimising the parasitic currents induced by surface tension (Popinet 2018;Tang et al 2021). Capillary effects are modelled as source terms in the Navier-Stokes equations using an adaptation of Brackbill's method (Brackbill, Kothe & Zemach 1992;Popinet 2009), which calculates the interface curvature by taking the finite-difference discretisation of the derivatives of interface height functions (Popinet 2009).…”

Section: Methodsmentioning

confidence: 99%

Fragmentation of colliding liquid rims

Tang,

Adcock,

Mostert

2024

J. Fluid Mech.

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We present direct numerical simulations of the splashing process between two cylindrical liquid rims. This belongs to a class of impact and collision problems with a wide range of applications in science and engineering, and motivated here by splashing of breaking ocean waves. Interfacial perturbations with a truncated white noise frequency profile are introduced to the rims before their collision, whose subsequent morphological development is simulated by solving the two-phase incompressible Navier–Stokes equation with the adaptive mesh refinement technique, within the Basilisk software environment. We first derive analytical solutions predicting the unsteady interfacial and velocity profiles of the expanding sheet forming between the two rims, and develop scaling laws for the evolution of the lamella rim under capillary deceleration. We then analyse the formation and growth of transverse ligaments ejected from the lamella rims, which we find to originate from the initial corrugated geometry of the perturbed rim surface. Novel scaling models are proposed for predicting the decay of the ligament number density due to the ongoing ligament merging phenomenon, and found to agree well with the numerical results presented here. The role of the mechanism in breaking waves is discussed further and necessary next steps in the problem are identified.

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Section: Methodsmentioning

confidence: 99%

Fragmentation of colliding liquid rims

Tang,

Adcock,

Mostert

2024

J. Fluid Mech.

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“…2015, 2019; Tang et al. 2021); such methods can represent interfacial topological change without a need for extensive special treatment. However, such techniques also tend to suffer from an unphysical and numerically uncontrolled perforation and fragmentation mode in thin films, which moreover compromises numerical convergence of the statistics of the resulting fragment populations (Chirco et al.…”

Section: Breakup Of Bag Filmsmentioning

confidence: 99%

Bag film breakup of droplets in uniform airflows

Tang,

Adcock,

Mostert

2023

J. Fluid Mech.

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We present novel numerical simulations investigating the bag breakup of liquid droplets. We first examine the viscous effect on the early-time drop deformation, comparing with theory and experiment. Next, a bag film forms at late time and is susceptible to spurious mesh-induced breakup in numerical simulations, which has prevented previous studies from reaching grid convergence of fragment statistics. We therefore adopt the manifold death (MD) algorithm which artificially perforates thin films once they reach a prescribed critical thickness independent of the grid size, controlled by a numerical parameter $L_{sig}$ . We show grid convergence of fragment statistics when utilising the MD algorithm, and analyse the fragment behaviour and bag film disintegration mechanisms including ligament breakup, node detachment and rim destabilisation. Our choice of the critical thickness parameter $L_{sig}$ is limited by numerical constraints and thus has not been matched to experiment or theory; consequently, the current simulations yield critical bag film perforation thicknesses larger than experimentally observed. The influence of the MD algorithm configuration on the bag breakup phenomena and statistics will be investigated in future work. We also study the effects of moderate liquid Ohnesorge number ( $0.005 \leqslant Oh \leqslant 0.05$ ) on the bag breakup process and fragment statistics, where a non-monotonic dependency of the average diameter of bag film fragments on $Oh$ is found. These results highlight the utility of the MD algorithm in multiphase simulations involving topological changes, and pave the way for physics-based numerical investigations into spume generation at the air–sea interface.

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Cavitation bubble dynamics and microjet atomization near tissue-mimicking materials

2023

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In recent years, considerable interest has been devoted to the interactions between cavitation bubbles and tissue-mimicking materials due to their promising applications in medicine and biomedical sciences. The strong fluid–structure interaction between a cavitation bubble and these elastic surfaces triggers unique collapse dynamics, characterized by bubble splitting and subsequent microjetting phenomena that can damage adjacent boundaries. In this work, we investigate how the elasticity of the boundary and the distance between the bubble and the elastic surface affect the bubble dynamics and the velocity of its microjet. To this end, we generate single laser-induced cavitation bubbles in the vicinity of agarose hydrogels with different degrees of elasticity and follow the bubble dynamics using high-speed imaging techniques, with a special focus on the formation and evolution of the microjets. We provide a time-resolved evidence of the atomization of the liquid microjet within the bubble, which precedes the establishment of a fully liquid microjet. The atomized portion of the microjet can reach supersonic velocities of up to 2000 ms−1, while the ensuing fully developed liquid microjet travels at averaged speeds of up to 1000 ms−1. To gain further insight into the bubble dynamics leading to the formation of these very fast microjets, we also propose a numerical model based on the boundary integral method and observe a remarkable agreement between the numerical simulations and the experimental observations.

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Effects of surface tension on the Richtmyer-Meshkov instability in fully compressible and inviscid fluids

Cited by 3 publications

References 47 publications

Fragmentation of colliding liquid rims

Fragmentation of colliding liquid rims

Bag film breakup of droplets in uniform airflows

Cavitation bubble dynamics and microjet atomization near tissue-mimicking materials

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