scholarly journals Computational Evaluation of Shock Wave Interaction with a Cylindrical Water Column

2021 ◽  
Vol 11 (11) ◽  
pp. 4934
Author(s):  
Viola Rossano ◽  
Giuliano De Stefano
Keyword(s):  
Shock Wave ◽  
Water Column ◽  
Wave Interaction ◽  
Navier Stokes ◽  
Plane Shock ◽  
Governing Equations ◽  
Computational Evaluation ◽  
Air Water Interface ◽  
The Mean ◽  
The Impact

Computational fluid dynamics was employed to predict the early stages of the aerodynamic breakup of a cylindrical water column, due to the impact of a traveling plane shock wave. The unsteady Reynolds-averaged Navier–Stokes approach was used to simulate the mean turbulent flow in a virtual shock tube device. The compressible flow governing equations were solved by means of a finite volume-based numerical method, where the volume of fluid technique was employed to track the air–water interface on the fixed numerical mesh. The present computational modeling approach for industrial gas dynamics applications was verified by making a comparison with reference experimental and numerical results for the same flow configuration. The engineering analysis of the shock–column interaction was performed in the shear-stripping regime, where an acceptably accurate prediction of the interface deformation was achieved. Both column flattening and sheet shearing at the column equator were correctly reproduced, along with the water body drift.

Plane shock wave interaction with a cylindrical water column

2016 ◽  
Vol 28 (5) ◽  
pp. 056102 ◽  
Author(s):  
S. Sembian ◽  
M. Liverts ◽  
N. Tillmark ◽  
N. Apazidis
Keyword(s):  
Shock Wave ◽  
Water Column ◽  
Wave Interaction ◽  
Plane Shock Wave ◽  
Plane Shock ◽  
Shock Wave Interaction

The structure of a shock wave in a fully ionized gas

1957 ◽  
Vol 3 (3) ◽  
pp. 275-285 ◽  
Author(s):  
J. D. Jukes
Keyword(s):  
Shock Wave ◽  
Navier Stokes ◽  
Plane Shock ◽  
Quasi Equilibrium ◽  
Ionized Gas ◽  
Temperature Changes ◽  
Numerical Iteration ◽  
Different Temperatures ◽  
The Mean ◽  
Wide Zone

The structure of a plane shock wave moving through a completely ionized plasma of protons and electrons is calculated. It is assumed that the two species of particles behave as two gases, each separately in a quasi-equilibrium state corresponding generally to two different temperatures. Navier-Stokes type equations with coefficients of viscosity and thermal conductivity appropriate to the two species are solved by numerical iteration.For very strong shocks it is found that both the velocity of electrons and protons and the temperature of the protons change in a distance about twice the mean path for momentum transfer between protons in the hot (shocked) gas. The electron temperature changes in about eight of these mean free paths, causing a relatively wide zone of hot electrons at low density ahead of the usual velocity shock-front. The density and temperature gradients of protons and electrons create an electric field.

scholarly journals Computational Evaluation of Aerodynamic Loading on Retractable Landing-Gears

Aerospace ◽  
2020 ◽  
Vol 7 (6) ◽  
pp. 68 ◽  
Author(s):  
Giuliano De Stefano ◽  
Nunzio Natale ◽  
Giovanni Paolo Reina ◽  
Antonio Piccolo
Keyword(s):  
Landing Gear ◽  
Navier Stokes ◽  
Governing Equations ◽  
Commercial Aircraft ◽  
Aerodynamic Loading ◽  
Computational Evaluation ◽  
The Mean ◽  
Landing Gears ◽  
Gear Systems ◽  
Dynamic Meshing

Computational fluid dynamics is employed to evaluate the mean aerodynamic loading on the retractable landing-gears of a regional transport commercial aircraft. The mean turbulent flow around simplified landing-gear systems including doors is simulated by using the Reynolds-averaged Navier–Stokes approach, where the governing equations are solved with a finite volume-based numerical method. Using a dynamic meshing method, the computational grid is automatically and continuously adapted to the time-changing geometry, while following the extension/retraction of the landing-gear systems. The temporal evolution of the aerodynamic forces on both the nose and the main landing-gears, along with the hinge moments of the doors, is numerically predicted. The proposed computational modeling approach is verified to have good practical potential when compared with reference experimental data provided by the Leonardo Aircraft structural loads group.

scholarly journals Прохождение плоской ударной волны через область тлеющего газового разряд

2019 ◽  
Vol 89 (1) ◽  
pp. 42
Author(s):  
Т.А. Лапушкина ◽  
А.В. Ерофеев ◽  
О.А. Азарова ◽  
О.В. Кравченко
Keyword(s):  
Shock Wave ◽  
Stokes Equations ◽  
Wave Structure ◽  
Gas Discharge ◽  
Navier Stokes ◽  
Plane Shock ◽  
Two Dimensional ◽  
Gas Temperature ◽  
Discharge Region ◽  
Navier Stokes Equations

AbstractThe interaction of a plane shock wave ( M = 5) with an ionized plasma region formed before the arrival of a shock wave by a low-current glow gas discharge is considered experimentally and numerically. In the experiment, schlieren images of a moving shock-wave structure resulting from the interaction and consisting of two discontinuities, convex in the direction of motion of the initial wave, are obtained. The propagation of a shock wave over the region of energetic impact is simulated on the basis of the two-dimensional Riemann problem of decay of an arbitrary discontinuity with allowance for the influence of horizontal walls. The systems of Euler and Navier–Stokes equations are solved numerically. The non-equilibrium of the processes in the gas-discharge region was simulated by an effective adiabatic index γ. Based on the calculations performed for equilibrium air (γ = 1.4) and for an ionized nonequilibrium gas medium (γ = 1.2), it is shown that the experimentally observed discontinuities can be interpreted as elements of the solution of the two-dimensional problem of decay of a discontinuity: a shock wave followed by a contact discontinuity. It is shown that a variation in γ affects the shape of the fronts and velocities of the discontinuities obtained. Good agreement is obtained between the experimental and calculated images of density and velocities of the discontinuities at a residual gas temperature in the gas discharge region of 373 K.

scholarly journals Computational Evaluation of Control Surfaces Aerodynamics for a Mid-Range Commercial Aircraft

Aerospace ◽  
2020 ◽  
Vol 7 (10) ◽  
pp. 139
Author(s):  
Nunzio Natale ◽  
Teresa Salomone ◽  
Giuliano De Stefano ◽  
Antonio Piccolo
Keyword(s):  
Flight Control ◽  
Realistic Model ◽  
Navier Stokes ◽  
Flight Control System ◽  
Commercial Aircraft ◽  
Virtual Experiments ◽  
Computational Evaluation ◽  
Aerodynamic Properties ◽  
The Mean ◽  
Control Surfaces

Computational fluid dynamics is employed to predict the aerodynamic properties of the prototypical trailing-edge control surfaces for a small, regional transport, commercial aircraft. The virtual experiments are performed at operational flight conditions, by resolving the mean turbulent flow field around a realistic model of the whole aircraft. The Reynolds-averaged Navier–Stokes approach is used, where the governing equations are solved with a finite volume-based numerical method. The effectiveness of the flight control system, during a hypothetical conceptual pre-design phase, is studied by conducting simulations at different angles of deflection, and examining the variation of the aerodynamic loading coefficients. The proposed computational modeling approach is verified to have good practical potential, also compared with reference industrial data provided by the Leonardo Aircraft Company.

Numerical study of a planar shock interacting with a cylindrical water column embedded with an air cavity

2017 ◽  
Vol 825 ◽  
pp. 825-852 ◽  
Author(s):  
Gaoming Xiang ◽  
Bing Wang
Keyword(s):  
Shock Wave ◽  
Water Column ◽  
Numerical Study ◽  
Incident Shock ◽  
Weno Scheme ◽  
Geometrical Parameters ◽  
Wave Impact ◽  
Planar Shock ◽  
Mach Numbers ◽  
The Impact

This paper performs a numerical study on the interaction of a planar shock wave with a water column embedded with/without a cavity of different sizes at high Weber numbers. The conservative-type Euler and non-conservative scalar two-equations representing the transportation of two-phase properties consist of the diffusion interface capture models. The numerical fluxes are computed by the Godunov-type Harten-Lax–van Leer contact Riemann solver coupled with an incremental fifth-order weighted essentially non-oscillatory (WENO) scheme. A third-order total variation diminishing (TVD) Runge–Kutta scheme is used to advance the solution in time. The morphology and dynamical characteristics are analysed qualitatively and quantitatively to demonstrate the breakup mechanism of the water column and formation of transverse jets under different incident shock intensities and embedded-cavity sizes. The jet tip velocities are extracted by analysing the interface evolution. The liquid column is prone to aerodynamic breakup with the formation of micro-mist at later stages instead of liquid evaporation because of the weakly heating effects of the surrounding air. It is numerically confirmed that the liquid-phase pressure will drop below the saturated vapour pressure, and the low pressure can be sustained for a certain time because of the focusing of the expansion wave, which accounts for the cavitation inside the liquid water column. The geometrical parameters of the deformed water column are identified, showing that the centreline width decreases but the transverse height increases nonlinearly with time. The deformation rates are nonlinearly correlated under different Mach numbers. The first transverse jet is found for a water column with an embedded cavity, whereas the water hammer shock and second jet do not occur under the impact of low intensity incident shock waves. The $x$-velocity component recorded at the rear stagnation point can remain unchanged for a comparable time after a declined evolution, which indicates that the downstream wall of the shocked water ring somehow moves uniformly. It can be explained that the acceleration of the downstream wall is balanced by the trailing shedding vortex, and this effect is more evident under higher Mach numbers. The increased enstrophy, mainly generated at the interface, demonstrates the competition of the baroclinic effects of the shock wave impact over dilatation.

Experimental and Numerical Study of Shock Wave Interaction with Perforated Plates

2004 ◽  
Vol 126 (3) ◽  
pp. 399-409 ◽  
Author(s):  
A. Britan ◽  
A. V. Karpov ◽  
E. I. Vasilev ◽  
O. Igra ◽  
G. Ben-Dor ◽  
...  
Keyword(s):  
Shock Wave ◽  
Numerical Study ◽  
Wave Interaction ◽  
Wave Pattern ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Perforated Plates ◽  
Shock Reflections

The flow developed behind shock wave transmitted through a screen or a perforated plat is initially highly unsteady and nonuniform. It contains multiple shock reflections and interactions with vortices shed from the open spaces of the barrier. The present paper studies experimentally and theoretically/numerically the flow and wave pattern resulted from the interaction of an incident shock wave with a few different types of barriers, all having the same porosity but different geometries. It is shown that in all investigated cases the flow downstream of the barrier can be divided into two different zones. Due immediately behind the barrier, where the flow is highly unsteady and nonuniform in the other, placed further downstream from the barrier, the flow approaches a steady and uniform state. It is also shown that most of the attenuation experienced by the transmitted shock wave occurs in the zone where the flow is highly unsteady. When solving the flow developed behind the shock wave transmitted through the barrier while ignoring energy losses (i.e., assuming the fluid to be a perfect fluid and therefore employing the Euler equation instead of the Navier-Stokes equation) leads to non-physical results in the unsteady flow zone.

scholarly journals Simulation of unsteady gas-particle flow induced by the shock-wave interaction with a particle layer

2020 ◽  
pp. 96-114
Author(s):  
В.Н. Емельянов ◽  
К.Н. Волков ◽  
А.Г. Карпенко ◽  
И.В. Тетерина
Keyword(s):  
Shock Wave ◽  
Wave Interaction ◽  
Particle Flow ◽  
Wave Flow ◽  
Governing Equations ◽  
Interphase Interaction ◽  
Shock Wave Interaction ◽  
Particle Layer ◽  
Wide Range ◽  
Energy Equations

На основе модели взаимопроникающих континуумов проводится численное моделирование нестационарного течения газовзвеси, возникающего при взаимодействии ударной волны со слоем инертных частиц. Каждая фаза описывается набором уравнений, выражающих законы сохранения массы, импульса и энергии. Межфазное взаимодействие учитывается при помощи источниковых членов в уравнениях изменения количества движения и энергии. Основные уравнения для газовой и дисперсной фаз имеют гиперболический тип, допускают запись в консервативной форме и решаются с использованием численного метода типа Годунова повышенного порядка точности. Для дискретизации уравнений по времени применяется метод Рунге-Кутты 3-го порядка. Построенная модель позволяет рассчитывать широкий спектр режимов течения газовзвеси, возникающих при изменении объемной концентрации дисперсной фазы. Обсуждаются вопросы, связанные с замыканием математической модели, а также детали реализации численной модели. Приводятся ударно-волновая структура течения и пространственно-временные зависимости концентрации частиц и других параметров потока. A numerical simulation of the unsteady gas-particle flow arising from the shock-wave interaction with a layer of inert particles is performed based on a continuum model. Each phase is described by a set of equations describing the conservation laws of mass, momentum and energy. The interphase interaction is taken into account using source terms in the momentum and energy equations. The governing equations for the gas and dispersed phases are of a hyperbolic type, they can be written in a conservative form and can be solved with a Godunov-type numerical method. A third order Runge-Kutta method is used to discretize the governing equations in time. The proposed model allows one to calculate a wide range of gas-particle flow regimes occurring when the volume concentration of the dispersed phase varies. The closure of the mathematical model and some details of numerical model implementation are discussed. The shock-wave flow structure as well as the space-time dependencies of particle concentration and other flow parameters are presented.

scholarly journals The Daily Resistive Index measurement useful tool in the estimation of the optimal time interval between two Shock Wave Lithotripsy sessions.

2015 ◽  
Vol 17 (2) ◽  
pp. 175
Author(s):  
Esin Yencilek ◽  
Aysegul Sarsılmaz ◽  
Ozgur Kilickesmez ◽  
Hakan Koyuncu ◽  
Bilal Eryildirim ◽  
...  
Keyword(s):  
Shock Wave ◽  
Shock Wave Lithotripsy ◽  
Resistive Index ◽  
Optimal Time ◽  
Time Interval ◽  
Index Measurement ◽  
The Mean ◽  
Group 2 ◽  
The Impact ◽  
Group 1

Aims: To monitor the impact of Shock Wave Lithotripsy (SWL) on the renal resisive index (RI) and to investigate the potential of the RI measurement for the estimation of the optimal duration between 2 SWL sessions. Material and methods: Thirty patients with single pelvis renalis stone were included. Participitants were grouped according to their age as group 1 (<40 years, mean age 36.2±3.9 years) and group 2 (≥40 years, mean age 55.4±6.5 years). RI measurement was performed in of all patients prior to SWL. After SWL, RI was monitored daily until RI returned to their pre-SWL values. Results: The mean stone size was 2 8.97±3.62 in group 1 and 10.08±4.67 mm in group 2 (p=0.077). Following SWL, the  RI value of both goups increased and the higher RI value was measured at the 24th hour as compared with their pre-SWL values (p<0.001). In day 2 RI of the groups declined, but the differences were still statistically different from their pre-SWL RI values (p<0.001). However, on the third day, RI of group 1 was close to their pre-SWL level (p=0.143). But, in group 2, RI value returned to their pre-SWL limits on day 4 (p=0.229). Conclusions: RI measurement gives important data regarding SWL related acute renal trauma and should be used as an US marker for recovery after SWL. 

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