A sharp-interface method for the simulation of shock-induced vaporization of droplets

Das, Pratik; Udaykumar, H. S.

doi:10.1016/j.jcp.2019.109005

Cited by 34 publications

(17 citation statements)

References 74 publications

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“…The combined effect of recirculated jet flow and spreading of the high-pressure region flattens the leeward side of the droplet and deforms it into a cupcake shape (figures 4n and 5 f ). The observed wave dynamics of droplet interaction with incident shock wave is in accordance with the previous work on shock-water-column interaction (Igra & Takayama 2003;Sembian et al 2016) and various two-dimensional numerical simulations using spherical dispersions (Mehta et al 2016;Sridharan et al 2016;Guan et al 2018;Das & Udaykumar 2020), indicating the axisymmetric nature of the stage I interaction. The continuous deformation of the droplet increases the projected area for aerodynamic drag, which further enhances the flattening of the liquid droplet (figures 4o and 5g) and leads to droplet breakup in later time instants.…”

Section: Shock-droplet Interaction Mechanismsupporting

confidence: 90%

“…A numerical simulation by Meng & Colonius (2015) and Guan et al (2018) illustrated the development of recirculating flow near the equator region and an upstream jet at the droplet wake, which eventually assists in droplet deformation and breakup. Similar wave and flow dynamics were observed in the numerical simulation by Das & Udaykumar (2020). In addition to deformable dispersions, several works were focused on understanding the wave dynamics of a planar shock wave interaction with solid dispersions (Tanno et al 2003;Sridharan et al 2015;Mehta et al 2016Mehta et al , 2018.…”

Section: Introductionsupporting

confidence: 62%

“…The transmitted wave moves inside the droplet, resulting in a high-pressure region behind it and an induced fluid flow towards the leeward side of the droplet (figure 4i) (Guan et al 2018). As the pressure waves can travel faster in water in comparison with air, the transmitted wave gets detached from the incident wave and reaches the droplet's leeward side at an earlier instant (figure 4c,j) (Sembian et al 2016;Das & Udaykumar 2020). On reaching the air-water interface at the leeward side, the transmitted wave reflects as an expansion wave (Z air < Z water ) (Henderson 1989) which focuses at a point inside droplet due to the concave profile of reflecting surface (figure 4d).…”

Section: Shock-droplet Interaction Mechanismmentioning

confidence: 99%

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Shock induced aerobreakup of a droplet

et al. 2021

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The multiscale dynamics of a shock–droplet interaction is crucial in understanding the atomisation of droplets due to external airflow. The interaction phenomena are classified into wave dynamics (stage I) and droplet breakup dynamics (stage II). Stage I involves the formation of different wave structures after an incident shock impacts the droplet surface. These waves momentarily change the droplet's ambient conditions, while in later times they are mainly influenced by shock-induced airflow. Stage II involves induced airflow interaction with the droplet that leads to its deformation and breakup. Primarily, two modes of droplet breakup, i.e. shear-induced entrainment and Rayleigh–Taylor piercing (RTP) (based on the modes of surface instabilities) were observed for the studied range of Weber numbers $(We\sim 30\text{--}15\,000)$ . A criterion for the transition between two breakup modes is obtained, which successfully explains the observation of RTP mode of droplet breakup at high Weber numbers $(We\sim 800)$ . For $We > 1000$ , the breakup dynamics is governed by the shear-induced surface waves. After formation, the Kelvin–Helmholtz waves travel on the droplet surface and merge to form a liquid sheet near the droplet equator. Henceforth, the liquid sheet undergoes breakup processes via nucleation of several holes. The breakup process is recurrent until the complete droplet disintegrates or external drag acting on the droplet is insufficient for further disintegration. At lower Weber numbers, the droplet undergoes complete deformation like a flattened disk, and a multibag mode of breakup based on RTP is observed.

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Section: Shock-droplet Interaction Mechanismsupporting

confidence: 90%

Section: Introductionsupporting

confidence: 62%

Section: Shock-droplet Interaction Mechanismmentioning

confidence: 99%

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Shock induced aerobreakup of a droplet

et al. 2021

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“…where R gas is the gas constant and χ e the evaporation coefficient which depends on the density ration λ = ρ l /ρ g between liquid and gas phase [40].…”

Section: The Thermally Driven Evaporation Modelmentioning

confidence: 99%

An improved Coupled Level Set and Volume of Fluid (i-CLSVoF) framework for droplet evaporation

Xia¹,

Kamlah²

2022

Preprint

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We present an improved Coupled Level Set and Volume of Fluid (i-CLSVoF) framework without explicit interface reconstruction for modelling micro-sized droplets with and without evaporation. A new surface tension force model with additional filtering steps is developed and implemented in the i-CLSVoF framework to suppress un-physical spurious velocities. Numerical benchmark cases demonstrate the excellence of the i-CLSVoF framework in reducing the un-physical spurious velocities. A simple yet efficient velocity-potential based approach is proposed to reconstruct a divergence-free velocity field for the advection of the free surface when the phase changes. The new approach fixes the numerical issues resulting from the evaporation-induced velocity jump at the interface. The smeared mass source term approach proposed in this work guarantees more numerical stability than the non-smeared approach.Two different evaporation models (constant mass flux and thermally driven evaporation models) are implemented into i-CLSVoF. Extensive numerical validations are conducted to validate the evaporation models.

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“…There are many reports on simulation of droplet/shock interactions using sharp-interface and diffuse-interface approaches at subcritical conditions [39][40][41][42][43][44]. However, there are only two reports that simulate the fuel droplet-shock interaction at transcritical conditions [45,46].…”

Section: Introductionmentioning

confidence: 99%

Shock wave interaction with a transcritical fuel droplet

Boyd

Jarrahbashi

2021

ICLASS

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Shock-droplet interactions occur in a spectrum of high-speed propulsion systems involving liquid fuels. When the combustion chamber pressure is above the critical pressure of the fuel, transcritical behaviour involving the transition from liquid-like to gas-like states is observed. Our understanding of multiphase-shock interaction is significantly less developed than its gasphase counterpart (i.e., shock-bubble interaction) and is particularly limited at transcritical conditions. We consider the interaction of a shockwave with a liquid n-dodecane droplet exposed to a nitrogen environment at a supercritical pressure. A fully-conservative diffuseinterface framework coupled with the Peng-Robinson equation of state is developed to accurately determine the state of the fluid as the shock propagates through the droplet. The shock-droplet interaction results show the development of interfacial instabilities and an axial jet.

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A sharp-interface method for the simulation of shock-induced vaporization of droplets

Cited by 34 publications

References 74 publications

Shock induced aerobreakup of a droplet

Shock induced aerobreakup of a droplet

An improved Coupled Level Set and Volume of Fluid (i-CLSVoF) framework for droplet evaporation

Shock wave interaction with a transcritical fuel droplet

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