Showing papers on "Shock wave published in 2020"
TL;DR: In this paper, the authors summarized the recent advances on the shock wave/boundary-layer interaction and its control in the internal and external flow fields of the hypersonic vehicle.
85 citations
TL;DR: In this paper, a mathematical model for the supersonic condensation flow of methane gas was established based on the improved Internal Consistent Classical Nucleation Theory (ICCT) model for single component gas.
80 citations
TL;DR: In this article, the origin and chaotic propagation of multiple detonative waves in the two-dimensional modelled rotating detonation combustor fueled by premixed hydrogen/air mixtures are numerically investigated with detailed chemical mechanism.
66 citations
TL;DR: The phase transition of Co3O4 into CoO is demonstrated by the impact of shock waves and the mechanism is studied and reported in this article, where the required quantity of Co 3O4 nanoparticle (NPs) is synthesized by co...
Abstract: The phase transition of Co3O4 into CoO is demonstrated by the impact of shock waves and the mechanism is studied and reported. The required quantity of Co3O4 nanoparticle (NPs) is synthesized by co...
65 citations
TL;DR: In this paper, a relation between scattering amplitudes and solutions to the Einstein field equations was proposed. But the relation was not considered for the case of a single massless scalar and a graviton.
Abstract: We study gravitational shock waves using scattering amplitude techniques. After first reviewing the derivation in General Relativity as an ultrarelativistic boost of a Schwarzschild solution, we provide an alternative derivation by exploiting a novel relation between scattering amplitudes and solutions to Einstein field equations. We prove that gravitational shock waves arise from the classical part of a three point function with two massless scalars and a graviton. The region where radiation is localized has a distributional profile and it is now recovered in a natural way, thus bypassing the introduction of singular coordinate transformations as used in General Relativity. The computation is easily generalized to arbitrary dimensions and we show how the exactness of the classical solution follows from the absence of classical contributions at higher loops. A classical double copy between gravitational and electromagnetic shock waves is also provided and for a spinning source, using the exponential form of three point amplitudes, we infer a remarkable relation between gravitational shock waves and spinning ones, also known as gyratons. Using this property, we infer a family of exact solutions describing gravitational shock waves with spin. We then compute the phase shift of a particle in a background of shock waves finding agreement with an earlier computation by Amati, Ciafaloni and Veneziano for particles in the high energy limit. Applied to a gyraton, it provides a result for the scattering angle to all orders in spin.
62 citations
TL;DR: In this article, the Eulerian finite element method is introduced to continuously simulate the shock wave and non-spherical bubble evolution stages near a horizontal solid wall with the volume of fluid method and pressure balance technique used to resolve the multi-medium flow.
48 citations
01 Nov 2020
46 citations
TL;DR: In this article, the analytical solutions of the Riemann problem for the isentropic Euler system with the logarithmic equation of state are derived explicitly for all the five different cases.
Abstract: The analytical solutions of the Riemann problem for the isentropic Euler system with the logarithmic equation of state are derived explicitly for all the five different cases. The concentration and cavitation phenomena are observed and analyzed during the process of vanishing pressure in the Riemann solutions. It is shown that the solution consisting of two shock waves converges to a delta shock wave solution as well as the solution consisting of two rarefaction waves converges to a solution consisting of four contact discontinuities together with vacuum states with three different virtual velocities in the limiting situation.
46 citations
TL;DR: In this article, the fluid-structure interaction of a flexible panel exposed to a ramp-induced shock-wave/boundary-layer interaction (SWBLI) at Mach 6 was investigated experimentally for transitional and turbulent environments.
Abstract: The fluid–structure interaction of a flexible panel exposed to a ramp-induced shock-wave/boundary-layer interaction (SWBLI) at Mach 6 is investigated experimentally for transitional and turbulent i...
45 citations
TL;DR: In this article, the authors developed a wet steam model to investigate the flow structure inside a supersonic separator with the co-existence of non-equilibrium condensation and shock waves.
45 citations
TL;DR: An efficient lattice Boltzmann model relying on a hybrid recursive regularization (HRR) collision operator on D3Q19 stencil is proposed for the simulation of three-dimensional high-speed compressible flows in both subsonic and supersonic regimes to reduce the complexity of correcting terms.
TL;DR: In this paper, a condensing flow model is developed to accurately predict the energy conversion within the supersonic separator, which reduces the energy loss by eliminating the oblique and expansion waves in the newly designed nozzle and improves the energy efficiency for natural gas processing.
TL;DR: In this paper, the sine-Gordon expansion method was used to solve the Gilson-Pickering equation by using the sinescale expansion method and various exact solitary wave solutions to the governing equation, such as shock wave, topological, non-topological, compound topological and soliton wave solutions.
Abstract: This study investigates the Gilson–Pickering equation by using the sine-Gordon expansion method. Sine-Gordon expansion method is one of the most powerful methods for solving the nonlinear partial differential equations.
We successfully construct various exact solitary wave solutions to the governing equation, such as shock wave, topological, non-topological, compound topological, and non-topological soliton wave solutions. In addition, the stability of the studied nonlinear equation is analyzed via the linear stability analysis. The 2D, 3D, and contour surfaces are also plotted for all obtained solutions.
TL;DR: In this article, a high-fidelity numerical solver, RYrhoCentralFoam, is developed based on OpenFOAM® to simulate turbulent compressible reactive flows.
TL;DR: In this paper, the interaction between an incident shock wave and a Mach-6 undisturbed hypersonic laminar boundary layer over a cold wall is addressed using direct numerical simulations (DNS) and wall-modeled large-eddy simulations (WMLES) at different angles of incidence.
Abstract: The interaction between an incident shock wave and a Mach-6 undisturbed hypersonic laminar boundary layer over a cold wall is addressed using direct numerical simulations (DNS) and wall-modeled large-eddy simulations (WMLES) at different angles of incidence. At sufficiently high shock-incidence angles, the boundary layer transitions to turbulence via breakdown of near-wall streaks shortly downstream of the shock impingement, without the need of any inflow free-stream disturbances. The transition causes a localized significant increase in the Stanton number and skin-friction coefficient, with high incidence angles augmenting the peak thermomechanical loads in an approximately linear way. Statistical analyses of the boundary layer downstream of the interaction for each case are provided that quantify streamwise spatial variations of the Reynolds analogy factors and indicate a breakdown of the Morkovin's hypothesis near the wall, where velocity and temperature become correlated. A modified strong Reynolds analogy with a fixed turbulent Prandtl number is observed to perform best. Conventional transformations fail at collapsing the mean velocity profiles on the incompressible log law. The WMLES prompts transition and peak heating, delays separation, and advances reattachment, thereby shortening the separation bubble. When the shock leads to transition, WMLES provides predictions of DNS peak thermomechanical loads within $\pm 10\%$ at a computational cost lower than DNS by two orders of magnitude. Downstream of the interaction, in the turbulent boundary layer, WMLES agrees well with DNS results for the Reynolds analogy factor, the mean profiles of velocity and temperature, including the temperature peak, and the temperature/velocity correlation.
TL;DR: In this article, the in-plane shock wave propagation in hexagonal lattices of graphene and boron nitride was investigated and it was shown that in graphene the shock wave radiated energy and slow down faster than in borón nitride, while in both materials the wave attenuation was faster for the waves moving along the armchair direction as compared to the zigzag direction.
01 Dec 2020
TL;DR: In this article, a new manually operated pressure driven shock tube is proposed and demonstrated using acoustic method, which is used to measure both pressure and time lag of shock wave between the sensors.
Abstract: A new manually operated pressure driven shock tube is proposed and demonstrated. Shock wave-associated parameters like velocity, Mach number, pressure, and temperature are computed using acoustic method. Experiment involves manually loading train of pressure pulses into a driver tube using a bicycle pump. The high pressure buildup in driver tube ruptures the diaphragm at critical pressure and generates a propagating shock wave in the driven section coupled with sensor section in which a couple of microphones are separated by a fixed distance. The propagating shock wave acoustical profile is recorded and its arrival time lag is measured using sound recording software. In a conventional method, piezo-electric pressure sensors are utilized to measure both pressure and time lag of shock wave between the sensors. In the proposed method, microphones are utilized to measure time lag of shock wave with sampling frequency of 768 KHz using computer supporting audio software. Utilizing time data, the said shock wave parameters are evaluated and reported. The performance of the proposed shock tube is compared with manually operated piston-driven Reddy tube.
TL;DR: In this paper, the authors investigate the impact of shock waves on Zinc Ferrite nanoparticles (ZnFe2O4) NPs and investigate the mechanism of shock wave induced magnetic phase transition.
Abstract: The present work is designed to investigate the impact of shock waves on Zinc Ferrite nanoparticles (ZnFe2O4) NPs. The test material was prepared by precipitation method and shock wave recovery experiment is done by tabletop pressure driven shock tube. The shock wave induced changes in structural, morphological and magnetic properties are noticed by various analytical techniques such as powder X-ray Diffractometer (PXRD), fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) and the obtained PXRD results shows no significant structural changes. Switchable paramagnetic to superparamagnetic behaviour is observed during the shock wave loaded conditions. The mechanism of shock wave induced magnetic phase transition is discussed.
TL;DR: In this paper, the authors evaluated the impact of the size and shape of the bleed and suction slots on the flow control efficiency of the secondary recirculation jet. And they showed that these factors can be omitted in the design process of the shock wave/boundary layer interaction model.
TL;DR: A Nomarski polarizing prism has been used in conjunction with a focused laser differential interferometer to measure the phase velocity of a density disturbance at sampling frequencies ≥10MHz.
Abstract: A Nomarski polarizing prism has been used in conjunction with a focused laser differential interferometer to measure the phase velocity of a density disturbance at sampling frequencies ≥10MHz. Use of this prism enables the simultaneous measurement of density disturbances at two closely spaced points that can be arbitrarily oriented about the instrument’s optical axis. The orientation is prescribed by rotating the prism about this axis. Since all four beams (one beam pair at each measurement point) propagate parallel to one another within the test volume, any bias imparted by density fluctuations away from the measurement plane on the disturbance phase velocity is minimized. A laboratory measurement of a spark-generated shock wave and a wind tunnel measurement of a second-mode instability wave on a cone model in a Mach 6 flow are presented to demonstrate the performance of the instrument. High-speed schlieren imaging is used in both cases to verify the results obtained with the instrument.
TL;DR: In this article, shock wave induced switchable phase transition (β to α and α to β) of a potassium sulfate (K2SO4) crystal is demonstrated, where the test crystals are subjected to shock waves of...
Abstract: In this research article, shock wave induced switchable phase transition (β to α and α to β) of potassium sulfate (K2SO4) crystal is demonstrated. The test crystals are subjected to shock waves of ...
TL;DR: In this article, a 2D numerical simulation of gaseous detonation with dilute water spray was conducted to clarify the mean structure of Gaseous explosion with water droplets.
Abstract: Two-dimensional (2-D) numerical simulations based on the Eulerian–Lagrangian method that take droplet break-up into account are conducted to clarify the mean structure of gaseous detonation laden with a dilute water spray. The premixed mixture is a slightly diluted stoichiometric hydrogen–oxygen mixture at low pressure. The simulated results are analysed via 2-D flow fields and statistical Favre spatiotemporal averaging techniques. Gaseous detonation with water droplets (WD) propagates stably with a velocity decrease compared with the dry Chapman–Jouguet speed. The mean structure of gaseous detonation with dilute water spray shares a similar structure as the one without water spray. However, the hydrodynamic thickness is changed due to the interaction with water spray. Overall interphase exchanges (mass, momentum and energy) that take place within the hydrodynamic thickness induce a decrease of the detonation velocity and lower the level of fluctuations downstream of the mean leading shock wave. Droplet break-up occurs downstream of the induction zone and in our case, the water vapour from the evaporation of water spray does not affect the reactivity of gaseous detonation. The laminar master equation for gaseous detonation laden with inert WD shows that the hydrodynamic thickness should rely on the gaseous sound speed, and works well as the working mixture is weakly unstable and its cellular structure is regular. The droplet flow regimes and break-up modes have also been determined. The characteristic lengths of detonation and interphase exchanges have been ordered under the present simulation conditions and have been shown to be intimately intertwined.
TL;DR: In this article, a new turbulence amplification mechanism was proposed based on the analysis of data from direct numerical simulation of an oblique shock-wave/flat-plate boundary layer interaction at Mach 225.
Abstract: The mechanism of turbulence amplification in shock-wave/boundary layer interactions is reviewed, and a new turbulence amplification mechanism is proposed based on the analysis of data from direct numerical simulation of an oblique shock-wave/flat-plate boundary layer interaction at Mach 225 In the upstream part of the interaction zone, the amplification of turbulence is not essentially shear driven, but induced by the interaction of the deceleration of mean flow with streamwise velocity fluctuations, which causes a rapid increase of turbulence intensity in the near-wall region In the downstream part of the interaction zone, the high turbulence intensity is mainly due to the free shear layer generated in the interaction zone During the initial stage of turbulence amplification, the characteristics of wall turbulence, including compact velocity streaks, streamwise vortices and an anisotropic Reynolds stress, are well preserved The mechanism proposed explains the high level of turbulence in the near-wall region observed in some experiments and numerical simulations
TL;DR: In this paper, the deformation response of polycrystalline Al microstructures at the atomic scale was investigated for various grain sizes and impact velocities (18-nm-100-nm) and simulations suggest an increase in shock front width and a decay in the velocity and the amplitude of the elastic precursor wave (Hugoniot elastic limit) as the wave travels through the microstructure.
TL;DR: In this article, the authors investigated the influence of geometry and operating procedures on the performance of four geometrically different shock tubes located in two laboratories, Texas A&M University and the University of Duisburg-Essen.
TL;DR: In this paper, the ice breaking caused by a pair of interacting collapsing bubbles was studied by an experimental approach, where bubbles were generated by an underwater electric discharge simultaneously, positioned either horizontally or vertically below a floating ice plate and observed via high-speed photography.
Abstract: In this work ice breaking caused by a pair of interacting collapsing bubbles was studied by an experimental approach. The bubbles were generated by an underwater electric discharge simultaneously, positioned either horizontally or vertically below a floating ice plate and observed via high-speed photography. The bubble-induced shock waves, which turn out to be crucial to the fracturing of the ice, were visualized using a shadowgraph method and also measured using pressure transduces. Unique bubble behaviour was observed, including bubble coalescence, bubble splitting, inclined counter-jets and asymmetric toroidal bubble collapse. Bubble dynamic properties, such as jet speed, jet energy and bubble centre displacement, were measured. Shock wave emission and ice breaking capability of the two bubbles were investigated over a range of inter-bubble and bubble–boundary distances. Regions where the damaging potential of the bubble pair are strengthened or weakened were summarized and possible reasons for the variation in the ice breaking capability were analysed based on bubble morphology, jet characteristics and shock wave pressure. The findings may contribute to more efficient ice breaking and also inspire new ways to manipulate cavitation bubble damage.
TL;DR: It can be noticed that bubble jetting is much less likely to occur on the considered scale due to the cushioning effects of surface tension on the intensity of the collapse, and the mechanical loads on a spherical particle tend to increase with a sphere-bubble size ratio ε, and decrease with their distance δ.
TL;DR: In this article, the authors used large eddy simulation (LES) in the sharp wedge configuration of Ganesh et al. to investigate partial cavitation over incipient, transitory and periodic regimes.