Impact Of Shock Wave Research Articles

Impact of interplanetary shock on parameters of plasma turbulence in the Earth’s magnetosheath

Data from the BMSW spectrometer, which measures the ion flux value and sometimes plasma parameters with a time resolution of 31 ms, allow the study of the parameters of turbulence of the solar wind and magnetosheath plasma on kinetic scales. In this work, the frequency spectra of the ion flux fluctuations before and after recording the interplanetary shock front in the Earth’s magnetosheath are compared based on these data. It is shown that, in contrast to the solar wind, where the exponential decay of the spectrum often occurs after the shock front on the kinetic scales, no such phenomenon is observed in the magnetosheath: the spectrum on these scales can be approximated by a power function in all the cases considered. In half of these cases, the spectrum slope on the kinetic scales does not change during the interplanetary shock propagation. The results indicate a weak impact of interplanetary shock waves on the parameters of the plasma turbulence. In addition, it is shown that an interplanetary shock does not change the level of intermittency of the ion flux in the magnetosheath at both low and high level before the front.

Consolidation of Bimetallic Nanosized Particles and Formation of Nanocomposites Depending on Conditions of Shock Wave Compaction

The authors consider and evaluate the physical parameters and regularities of the process of consolidation of Fe–Cu, Cu–Nb, Ag–Ni, Fe–Pb nanoparticles when creating composite materials by means of shock wave compaction. As a result of theoretical consideration of explosive compaction process, researchers established and discussed the physical process conditions, established a number of threshold pressure values corresponding to different target indicators of the state of the compact. The time of shock wave impact on powders for powder consolidation was estimated.

Impact of shock waves on the conductive properties and structure of MgB2 tapes

This article presents data on shock waves effect on the structure and the critical current of superconducting MgB 2 tapes. To generate shock waves, a plasma focus installation (PF) was used. The conductive characteristics of the superconducting tapes dependence on the intensity of the impact and the number of shock pulses were studied. A distinct pattern of change in critical currents in transversal and longitudinal magnetic fields in the range of 2–9 T is studied at a temperature of 4.2 K. The microstructure of the superconducting tape and chemical composition of its layer are studied in the original state and after the shock wave effect. Changes were found in a microstructure of layers of MgB 2 (granulation, subdivision of grains and consolidation), which arose due to the shock-wave impact (SWI), are found. The possibility of increasing the critical current of tapes on 50–80 A in a transversal magnetic field of 2–3 T by means of SWI has been established. In a parallel magnetic field, the impact of the shock effect was essential in magnetic fields lower than 4 T.

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

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.

Unsteady drag following shock wave impingement on a dense particle curtain measured using pulse-burst PIV

Unsteady drag following shock wave impingement on a dense particle curtain measured using pulse-burst PIV

A Source Model for Ejecta

We present a Richtmyer–Meshkov instability based model for the ejected mass per unit area produced when a shockwave impinges upon a free surface with specified surface roughness amplitude and wavelength. The model is valid for sinusoidal and non-sinusoidal surface profiles and for multiple shocks, and is readily implemented in hydrodynamic computer codes. We compare the model with microscopic and macroscopic direct numerical simulations and with an extensive Sn experimental data set. The model works well for all surface profiles and captures both the time evolution and total mass for all shapes considered.

Effects of nanobubble collapse on cell membrane integrity.

Recent studies have shown that ultrasound is used to open drug-carrying liposomes to release their payloads; however, a shockwave energetic enough to rupture lipid membranes can cause collateral damage to surrounding cells. Similarly, a destructive shockwave, which may be used to rupture a cell membrane in order to lyse the cell (e.g., as in cancer treatments) may also impair or destroy nearby healthy tissue. To address this problem, we use dissipative particle dynamic (DPD) simulation to investigate the addition of a cavitation bubble between the shockwave and the model cell membrane to alter the shockwave front, allowing low-velocity shockwaves to specifically damage an intended target. We focus specifically on a spherical lipid bilayer model, and note the effect of shockwave velocity, bubble size, and orientation on the damage to the model cell. We show that a cavitation bubble greatly decreases the necessary shockwave velocity required to damage the lipid bilayer and rupture the model cell. The cavitation bubble focuses the kinetic energy of the shockwave front into a smaller area, inducing penetration at the edge of the model cell. With this work, we provide a comprehensive approach to the intricacies of model cell destruction via shockwave impact, and hope to offer a guideline for initiating targeted cellular destruction using induced cavitation bubbles and low-velocity shockwaves.

Adaptive THINC-GFM for compressible multi-medium flows

In this paper, a THINC (tangent of hyperbola for interface capturing) (Xiao F. et al., 2005) [26] coupled with GFM (Ghost Fluid Method) is proposed for numerical simulation of compressible multi-medium flows. The THINC scheme, which was first developed for incompressible flows, is applied for capturing the distorted material interface of compressible flows. The hybrid WENO (weighted essentially non-oscillatory) scheme with the blocked structured adaptive mesh refinement (AMR) method is implemented. Load balancing is considered in the parallel computing. Several well documented numerical tests are performed and the results show that the THINC scheme behaviors better in mass conservation. It is the first endeavor to implement THINC scheme with adaptive mesh for computing the compressible multiphase problems. The shock wave–helium bubble interaction test reveals that the present method is efficient in prediction of the deformed interface. The solver is further validated by shock wave impact SF6 interface with square, rectangle, forward and backward triangle shapes in which the wave positions and intersecting angles are compared quantitatively. Finally, the collapse of an air bubble under shock in water is simulated, global agreement with experimental and other numerical results are obtained.

Discrete Particle Method for Simulating Hypervelocity Impact Phenomena.

In this paper, we introduce a computational model for the simulation of hypervelocity impact (HVI) phenomena which is based on the Discrete Element Method (DEM). Our paper constitutes the first application of DEM to the modeling and simulating of impact events for velocities beyond 5 . We present here the results of a systematic numerical study on HVI of solids. For modeling the solids, we use discrete spherical particles that interact with each other via potentials. In our numerical investigations we are particularly interested in the dynamics of material fragmentation upon impact. We model a typical HVI experiment configuration where a sphere strikes a thin plate and investigate the properties of the resulting debris cloud. We provide a quantitative computational analysis of the resulting debris cloud caused by impact and a comprehensive parameter study by varying key parameters of our model. We compare our findings from the simulations with recent HVI experiments performed at our institute. Our findings are that the DEM method leads to very stable, energy–conserving simulations of HVI scenarios that map the experimental setup where a sphere strikes a thin plate at hypervelocity speed. Our chosen interaction model works particularly well in the velocity range where the local stresses caused by impact shock waves markedly exceed the ultimate material strength.

Numerical simulation of the deformation behavior of metallic materials under cavitation induced load in the incubation period

Numerical simulations are performed to improve the understanding of the pit formation in metallic materials due to cavitation-induced impacts. Under the influence of cavitation, metallic materials show plastically deformed surface regions, called pits, which are created due to the high impact pressure induced by a cavitation bubble collapse. Both the observation of the collapse and the measurement of the wall-load development require complex experiments. In this study, isolated wall-near bubble collapses are calculated with the help of CFD-simulations to evaluate the radial pressure distribution regarding the temporal maximum of pressure, further referred to as “wall-load profile”. The resulting wall-load profiles show a different number of local maxima, depending on the dominant hydrodynamic mechanism, i.e. liquid jet- or shock wave impact. With regard to the corresponding standoff-distance L0/R0, different cases of possible wall-load profiles are classified. These wall-loads are implemented into a Finite-Element (FE) software to visualize the elastic and plastic material response for three different model materials. The resulting pit geometries and the corresponding plastic strain distributions vary in accordance to the applied wall-load profile, which is directly affected by the dominant hydrodynamic mechanism. In certain cases, the resulting pits in the material show plateau-like displacements with crescent-shaped plastic strain distributions, which are related to the collapse of a toroidal bubble fragment. In addition to this, cavitation pits are generated in a copper specimen by short-term cavitation experiments. Selected pits are exemplarily measured by atomic force microscopy and then qualitatively compared to the numerically calculated pit geometries.

New hydrate formation methods in a liquid-gas medium

Conceptually new methods of hydrate formation are proposed. The first one is based on the shock wave impact on a water-bubble medium. It is shown that the hydrate formation rate in this process is typically very high. A gas hydrate of carbon dioxide was produced. The process was experimentally studied using various initial conditions, as well as different external action magnitudes. The obtained experimental data are in good agreement with the proposed model. Other methods are based on the process of boiling liquefied gas in an enclosed volume of water (explosive boiling of a hydrating agent and the organization of cyclic boiling-condensation process). The key features of the methods are the high hydrate formation rate combined with a comparatively low power consumption leading to a great expected efficiency of the technologies based on them. The set of experiments was carried out. Gas hydrates of refrigerant R134a, carbon dioxide and propane were produced. The investigation of decomposition of a generated gas hydrate sample was made. The criteria of intensification of the hydrate formation process are formulated.

Molecular modeling of transmembrane delivery of paclitaxel by shock waves with nanobubbles

The development of advanced delivery strategies for anticancer drugs that can permeate through cellular membranes is urgently required for biomedical applications. In this work, we investigated the dynamic transmembrane behavior of paclitaxel (PTX), a powerful anticancer drug, under the combined impact of shock waves and nanobubbles, by using atomistic molecular dynamics simulations. Our simulations show that the PTX molecule experiences complicated motion modes during the action process with the membrane, as a consequence of its interplay with the lipid bilayer and water, under the joint effect of the shock wave and nanobubble. Moreover, it was found that the transmembrane movement of PTX is closely associated with the conformation changes of PTX, as well as the structural changes of the membrane (e.g., compression and poration in membrane). The nanobubble collapse induced by the shock wave, the proper PTX location with respect to the nanobubble, and a suitable nanobubble size and shock impulse are all necessary for the delivery of PTX into the cell. This work provides a molecular understanding of the interaction mechanism between drug molecules and cell membranes under the influence of shock waves and nanobubbles, and paves the way for exploiting targeted drug delivery systems that combine nanobubbles and ultrasound.

Effect of continuous or discrete shock wave generators on supersonic film cooling

The present study investigates the flow fields for supersonic film cooling with various three-dimensional shock wave generators. This study investigates the effect of the shock wave intensity, shock wave generator width and coolant inlet Mach number on the supersonic film cooling. The results indicate that the impinging shock wave increases the wall pressure and the turbulent kinetic energy in the boundary layer, with the lower Mach numbers in the boundary layer reducing the film cooling effectiveness for the cases with the shock wave generator as wide as the flow channel. For a shock wave generator that is not as wide as the flow channel, the pressure and film cooling effectiveness are not evenly distributed. A wider shock wave generator reduces the film cooling effectiveness upstream of the protected wall. The 30mm shock wave generator had the lowest film cooling effectiveness in the middle part and downstream of the protected wall mainly because the uneven pressure distribution causes a z-direction secondary flow in the boundary layer which reduces the cooling film layer thickness in the middle part of the protected region and increases the interaction between the cooling stream and the main stream which reduces the film cooling effectiveness.

Planar Slip Condition For Mesh Morphing Using Radial Basis Functions

An original approach to morph meshes including slip planes is proposed. Extending the classical interpolation scheme based on Radial Basis Functions (RBF), it preserves the linear property, linking the deformation response to the known displacements, underlying the RBF formalism. No post-correction stage, nor extra not-moving control points, are required to enforce in plane displacements. Accuracy and robustness are evaluated for a 2D configuration where a shock-wave impinges on a cross-flow flexible panel. Analysis is based on deformation quality metrics derived from the displacement field gradient, keeping the proposed approach free from connectivity information. 3D applications are briefly illustrated by the tip of an aero engine fan subjected to conjugated parameterized variations of tip clearance and stagger angle.

Extracorporal Shock Waves Activate Migration, Proliferation and Inflammatory Pathways in Fibroblasts and Keratinocytes, and Improve Wound Healing in an Open-Label, Single-Arm Study in Patients with Therapy-Refractory Chronic Leg Ulcers

Background/Aims: Chronic leg ulcers (CLUs) are globally a major cause of morbidity and mortality with increasing prevalence. Their treatment is highly challenging, and many conservative, surgical or advanced therapies have been suggested, but with little overall efficacy. Since the 1980s extracorporal shock wave therapy (ESWT) has gained interest as treatment for specific indications. Here, we report that patients with CLU showed wound healing after ESWT and investigated the underlying molecular mechanisms. Methods: We performed cell proliferation and migration assays, FACS- and Western blot analyses, RT-PCR, and Affymetrix gene expression analyses on human keratinocytes and fibroblasts, and a tube formation assay on human microvascular endothelial cells to assess the impact of shock waves in vitro. In vivo, chronic therapy-refractory leg ulcers were treated with ESWT, and wound healing was assessed. Results: Upon ESWT, we observed morphological changes and increased cell migration of keratinocytes. Cell-cycle regulatory genes were upregulated, and proliferation induced in fibroblasts. This was accompanied by secretion of pro-inflammatory cytokines from keratinocytes, which are known to drive wound healing, and a pro-angiogenic activity of endothelial cells. These observations were transferred “from bench to bedside”, and 60 consecutive patients with 75 CLUs with different pathophysiologies (e.g. venous, mixed arterial-venous, arterial) were treated with ESWT. In this setting, 41% of ESWT-treated CLUs showed complete healing, 16% significant improvement, 35% improvement, and 8% of the ulcers did not respond to ESWT. The induction of healing was independent of patient age, duration or size of the ulcer, and the underlying pathophysiology. Conclusions: The efficacy of ESWT needs to be confirmed in controlled trials to implement ESWT as an adjunct to standard therapy or as a stand-alone treatment. Our results suggest that EWST may advance the treatment of chronic, therapy-refractory ulcers.

Numerical simulation of high-velocity projectile interactions with groups of spaced rods and plates

The study of the problem of protecting the elements of constructions from impact loadings is very important due to the constant perfection of the means of shock-wave impact on the objects of modern technology. Creating of a reliable way to protect structures from destruction by high-velocity elongated projectiles dictates a need to develop different ways to counter the penetration into target.

Experimental simulation of blast loading on structural elements using rarefaction waves – theoretical analysis

An experimental approach aiming at producing blast loading on structural elements without using either an explosive charge or an impact load, shock waves or compression waves, was investigated theoretically. The transient pressure pulse loading is produced by a transient differential pressure gradient created by a timely sudden pressure release from two connected chambers in between which a target plate is placed. It was shown that this test facility is capable of producing uniform pulse loading on the face of the tested element. An effective model with lumped parameters has been developed to simulate the problem and calculate the resulting blast pulses. The model allows analysis of the basic characteristics of the blast pulses depending on a predefined initial pressure, on the chambers volumes and on the exit air release opening areas. The following characteristics of a blast pulse are studied with that model: peak pressure, built-up duration and pressure drop to zero duration. Both short pulses and pulses with a plateau segment and with an infinite duration are considered.The effect of the filling gas properties on the resulting blast pressures acting on the target was investigated including a diatomic (air) and monatomic (helium) gases. The analytical results are compared with computational results obtained from simulations using the AUTODYN software. Comparisons are also made with experimental data. Excellent agreement is obtained between the calculated pressure time histories predicted by the proposed model and the computational and measured experimental pressure signals. The new presented model with lumped parameters allows an effective analysis of any experiment using that experimental system and definitely will help in planning experiments with specific blast characteristics through proper selection of the suitable parameters to achieve the planned experiment goal.

Research on fast solid-state chemical reactions at the Siberian Synchrotron and Terahertz Radiation Center

The potent equipment of the shared-use center “Siberian Synchrotron and Terahertz Radiation Center” at Budker Institute of Nuclear Physics of the Siberian Branch of the Russian Academy of Sciences (BINP SB RAS) enables conduction of time-resolved X-ray diffraction experiments using synchrotron radiation of the VEPP-3/VEPP-4 storage rings. These experiments are performed mostly for institutions of the Siberian Branch of the Russian Academy of Sciences (SB RAS). The experiments yielded novel techniques, which have been implemented for investigation into the dynamics of the nucleation and formation of nanoparticles under explosion and shock wave impact with a nanosecond-scale time resolution (the X-ray exposure time is 73 ps), dynamics of structural transformations in chemical reactions, and kinetics of chemical reactions during gasless combustion (SHS) with a millisecond-scale time resolution, obtaining structural information about the state of catalysts and so on.

Simulating sympathetic detonation using the hydrodynamic models and constitutive equations

A Sympathetic detonation (SD) is a detonation of an explosive charge by a nearby explosion. Most of times it is unintended while the impact of blast fragments or strong shock waves from the initiating donor explosive is the cause of SD. We investigate the SD of a cylindrical explosive charge (64 % RDX, 20 % Al, 16 % HTPB) contained in a steel casing. The constitutive relations for high explosive are obtained from a thermo-chemical code that provides the size effect data without the rate stick data typically used for building the rate law and equation of state. A full size SD test of eight pallet-packaged artillery shells is performed that provides the pressure data while the hydrodynamic model with proper constitutive relations for reactive materials and the fragmentation model for steel casing is conducted to replicate the experimental findings. The work presents a novel effort to accurately model and reproduce the sympathetic detonation event with a reduced experimental effort.

Orifice Design of a Pilot-Operated Pressure Relief Valve

An important safety factor to be considered when designing a plant is the prevention of overpressure-induced explosions, to which many plants are vulnerable because of pressurized fluids in plant components. A pilot-operated pressure relief valve is a core device for venting off overpressure formed inside vessels and pipelines. The pilot-operated pressure relief valve has a highly complicated structure, and its design and production should be thoroughly studied. In this study, a simplified structure for the pilot-operated pressure relief valve was proposed to facilitate the design and production processes, and the effective ranges of its design variables were determined to enable the prediction of the impact of the design variables in the design and production processes. The ranges determined were validated by a numerical flow analysis and experiment as follows. We calculated the maximum orifice diameter at which the main valve does not open and examined the minimum orifice diameter that can resist the impact of strong shock waves. Additionally, we defined the orifice diameter range that ensures the stable opening and closing of the main valve under various pressure conditions. The effective ranges of the design variables determined in this study can be used to ensure safe operation of a pilot-operated pressure relief valve under various pressure conditions with the design of the proposed simplified structure.