Abstract:In this paper, we present simulation results for the three-dimensional, shock-driven Kelvin-Helmholtz instability. Simulations are performed with a Mach 2.0 shock propagating through a finite-diameter cylindrical column of dense gas inclined at an angle θ with respect to the shock plane. After passage of the shock, the gas curtain has accelerated along its axis and a Kelvin-Helmholtz instability forms on the column surface. This is the first known numerical reproduction of this phenomena in three dimensions, w… Show more
“…For detailed comparisons of simulations to experiment, see Romero et al. (2021 b , 2022). Figure 8.Normalized KH wavelengths at different angles for experiments () and simulations ().…”
Section: Resultsmentioning
confidence: 99%
“…This may indicate that the simulation resolution is insufficient to resolve the short wavelengths that occur at smaller initial tilt angles and is not necessarily a failing of the proposed wavelength selection mechanism. For detailed comparisons of simulations to experiment, see Romero et al (2021bRomero et al ( , 2022.…”
Section: Resultsmentioning
confidence: 99%
“…2021 a , c ) and three-dimensional (3-D) heavy-gas columns (Romero et al. 2021 b , 2022) to verify the mechanism leading to SDKHI and to analyse the effect of the flow dimensionality on the shock–column interaction. Simulations were run at Mach numbers ranging from 1.13 to 2.0.…”
We present a statistical characterization of the interaction between a planar shock and a finite-diameter, cylindrical column of dense gas based on three-dimensional, large-eddy simulation results. In the simulation, the column of gas is initially inclined at an angle
$\alpha _0$
with respect to the shock plane. Effects of the initial column angle on the mixing characteristics are examined at Mach number 2.0 for column incline angles
$1^\circ$
,
$5^\circ$
,
$10^\circ$
and
$30^\circ$
. Mean velocity profiles show that the column angle affects the gas velocity components in the vertical plane, but not in the spanwise direction. The gas undergoes higher initial upward acceleration at larger initial column incline angles. With time, the gas motion tends to become one-dimensional in the streamwise direction. Initially, velocity fluctuations are most intense within the interior of the column, but concentrate near the column leading edge over time. At high wavenumbers
$\kappa$
, the turbulent kinetic energy spectra follow a power-law scaling of
$\kappa ^{-1}$
. The structure functions of the mass fraction do not clearly demonstrate power-law scaling except at early times for
$\alpha _0=30^\circ$
, manifesting overall trends very similar to those observed in earlier experiments. Probability distributions of the mass fraction show independence of the mean and the standard deviation of the mixed gas on
$\alpha _0$
. The column angle was also found to have little effect on the mixing efficiency characterized by the molecular mixedness. Velocity components in the streamwise and transverse directions tend towards a bimodal distribution for larger
$\alpha _{0}$
.
“…For detailed comparisons of simulations to experiment, see Romero et al. (2021 b , 2022). Figure 8.Normalized KH wavelengths at different angles for experiments () and simulations ().…”
Section: Resultsmentioning
confidence: 99%
“…This may indicate that the simulation resolution is insufficient to resolve the short wavelengths that occur at smaller initial tilt angles and is not necessarily a failing of the proposed wavelength selection mechanism. For detailed comparisons of simulations to experiment, see Romero et al (2021bRomero et al ( , 2022.…”
Section: Resultsmentioning
confidence: 99%
“…2021 a , c ) and three-dimensional (3-D) heavy-gas columns (Romero et al. 2021 b , 2022) to verify the mechanism leading to SDKHI and to analyse the effect of the flow dimensionality on the shock–column interaction. Simulations were run at Mach numbers ranging from 1.13 to 2.0.…”
We present a statistical characterization of the interaction between a planar shock and a finite-diameter, cylindrical column of dense gas based on three-dimensional, large-eddy simulation results. In the simulation, the column of gas is initially inclined at an angle
$\alpha _0$
with respect to the shock plane. Effects of the initial column angle on the mixing characteristics are examined at Mach number 2.0 for column incline angles
$1^\circ$
,
$5^\circ$
,
$10^\circ$
and
$30^\circ$
. Mean velocity profiles show that the column angle affects the gas velocity components in the vertical plane, but not in the spanwise direction. The gas undergoes higher initial upward acceleration at larger initial column incline angles. With time, the gas motion tends to become one-dimensional in the streamwise direction. Initially, velocity fluctuations are most intense within the interior of the column, but concentrate near the column leading edge over time. At high wavenumbers
$\kappa$
, the turbulent kinetic energy spectra follow a power-law scaling of
$\kappa ^{-1}$
. The structure functions of the mass fraction do not clearly demonstrate power-law scaling except at early times for
$\alpha _0=30^\circ$
, manifesting overall trends very similar to those observed in earlier experiments. Probability distributions of the mass fraction show independence of the mean and the standard deviation of the mixed gas on
$\alpha _0$
. The column angle was also found to have little effect on the mixing efficiency characterized by the molecular mixedness. Velocity components in the streamwise and transverse directions tend towards a bimodal distribution for larger
$\alpha _{0}$
.
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