Rayleigh-Taylor Instability of a Miscible Fluid at the Interface: Direct Numerical Simulation

Bhole, Ashish; Sengupta, Soumyo; Sengupta, Aditi; Shruti, Koulgi; Sharma, Nidhi

doi:10.1142/9789814635165_0047

Cited by 3 publications

(1 citation statement)

References 5 publications

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“…Most of RTI simulations [2,3,5] are reported using incompressible formulation. Present use of compressible NSE [1,4] helps remove this major discrepancy. It is noted [6] that the issue of compressibility is highly challenging and direct numerical simulations are the best way to assess the validity of Boussinesq approximation.…”

Section: Introductionmentioning

confidence: 99%

Effects of Error on the Onset and Evolution of Rayleigh–Taylor Instability

Sengupta

et al. 2017

Notes on Numerical Fluid Mechanics and Multidisciplinary Design

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Here we investigate effects of error in simulating Rayleigh Taylor instability (RTI). The error metrics are evaluated based on the correct spectral analysis of a model equation by Sengupta et al. (J Comput Phys 226:1211-1218, 2007) [13]. The geometry for RTI consists of a rectangular box with a partition at mid-height separating two volumes of air kept at a temperature difference of 70 K. This helps avoiding Boussinesq approximation and the present time-accurate computations for compressible Navier-Stokes equation (NSE) in 2D are reported. Computations for CFL numbers of 0.09 and 0.009 shows completely different onset of RTI, while the terminal mixed stage appears similar. The difference is traced to very insignificant difference in the value of numerical amplification factor for the two CFL numbers.

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Section: Introductionmentioning

confidence: 99%

Effects of Error on the Onset and Evolution of Rayleigh–Taylor Instability

Sengupta

et al. 2017

Notes on Numerical Fluid Mechanics and Multidisciplinary Design

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Non-equilibrium Thermodynamics of Rayleigh–Taylor Instability

Sengupta

et al. 2016

Int J Thermophys

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Roles of bulk viscosity on Rayleigh-Taylor instability: Non-equilibrium thermodynamics due to spatio-temporal pressure fronts

Sengupta

Sharma

et al. 2016

Physics of Fluids

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Direct numerical simulations of Rayleigh-Taylor instability (RTI) between two air masses with a temperature difference of 70 K is presented using compressible Navier-Stokes formulation in a non-equilibrium thermodynamic framework. The two-dimensional flow is studied in an isolated box with non-periodic walls in both vertical and horizontal directions. The non-conducting interface separating the two air masses is impulsively removed at t = 0 (depicting a heaviside function). No external perturbation has been used at the interface to instigate the instability at the onset. Computations have been carried out for rectangular and square cross sections. The formulation is free of Boussinesq approximation commonly used in many Navier-Stokes formulations for RTI. Effect of Stokes’ hypothesis is quantified, by using models from acoustic attenuation measurement for the second coefficient of viscosity from two experiments. Effects of Stokes’ hypothesis on growth of mixing layer and evolution of total entropy for the Rayleigh-Taylor system are reported. The initial rate of growth is observed to be independent of Stokes’ hypothesis and the geometry of the box. Following this stage, growth rate is dependent on the geometry of the box and is sensitive to the model used. As a consequence of compressible formulation, we capture pressure wave-packets with associated reflection and rarefaction from the non-periodic walls. The pattern and frequency of reflections of pressure waves noted specifically at the initial stages are reflected in entropy variation of the system.

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Rayleigh-Taylor Instability of a Miscible Fluid at the Interface: Direct Numerical Simulation

Cited by 3 publications

References 5 publications

Effects of Error on the Onset and Evolution of Rayleigh–Taylor Instability

Effects of Error on the Onset and Evolution of Rayleigh–Taylor Instability

Non-equilibrium Thermodynamics of Rayleigh–Taylor Instability

Roles of bulk viscosity on Rayleigh-Taylor instability: Non-equilibrium thermodynamics due to spatio-temporal pressure fronts

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