Shock Wave Research Articles

Complete extraction of main pancreatic duct residual and microstones using an 8-wire basket catheter

Extracorporeal shock wave lithotripsy (ESWL), pancreatoscopy-guided electrohydraulic lithotripsy (EHL), and endoscopic retrograde cholangiopancreatography (ERCP) are primary treatments for symptomatic main pancreatic duct (MPD) stones. However, incomplete clearance of residual/microstones post-treatment may cause symptom recurrence. We hypothesized that the 8-wire biliary basket catheter could be suitable for MPD stone extraction and aimed to analyze its ability to achieve more complete clearance of MPD residual/microstones. Patients suspected to have MPD residual/microstones ≤5 mm because of abdominal symptoms, computed-tomography examination results, and pancreatography results after previous therapy, including ERCP, EHL, and ESWL, were retrospectively enrolled. Patients with severe MPD stenosis/biliary obstruction requiring ERCP drainage were excluded. Extraction of residual/microstones was attempted using an 8-wire basket that is widely expandable in the narrow pancreatic duct and can capture and sweep stones in the narrow pancreatic duct. Technical success was defined as the extraction of residual/microstones. The primary outcome was the technical success rate. Secondary outcomes were therapeutic details of stone extraction using the 8-wire basket catheter, including symptom improvements. The technical success rate was 100% for seven patients; 1–8 residual/microstones were extracted. An improvement was observed in five patients with symptoms after the previous therapy. Three patients underwent residual stone extraction after extraction using a dedicated basket. No patient experienced symptom recurrence during the 270-day follow-up period. The 8-wire basket resulted in successful MPD residual/microstone extraction and pancreatic symptom improvement. This method may prevent symptom recurrence caused by incomplete residual/microstone clearance.

Observation of Two-Dimensional Dam Break Flow and a Gaseous Phase of Solitons in a Photon Fluid.

We report the observation of a two-dimensional (2D) dam break flow of a photon fluid in a nonlinear optical crystal. By precisely shaping the amplitude and phase of the input wave, we investigate the transition from one-dimensional (1D) to 2D nonlinear dynamics. We observe wave breaking in both transverse spatial dimensions with characteristic timescales determined by the aspect ratio of the input box-shaped field. The interaction of dispersive shock waves propagating in orthogonal directions gives rise to a 2D ensemble of solitons. Depending on the box size, we report the evidence of a dynamic phase characterized by a constant number of solitons, resembling a 1D soliton gas in integrable systems. We measure the statistical features of this gaslike phase. Our findings pave the way to the investigation of collective solitonic phenomena in two dimensions, demonstrating that the loss of integrability does not disrupt the dominant phenomenology.

Numerical investigation of the effect of laser peen forming process parameters on 1060 aluminium sheets under preload

Abstract Laser peen forming process changes the shape of the metal sheet or plate by plastic deformation caused by laser induced mechanical shock wave. The bending behavior of 1060 aluminium sheets under laser peen forming (LPF) are studied numerically taking into account the various laser peening process parameters for two distinct cases; with and without preload. Modal analysis has been performed on 3D finite element model (FEM) to stop post-shock oscillations. A time-dependent and space-dependent pressure distribution is applied to the laser-peened area along with preload at the free end. The numerical comparison of bending angles and surface profile of 1060 aluminium sheets under laser peen forming are studied for both the cases, with and without preload. Preloading provides better surface profile for same bending angle for a no laser shock overlap.

CSWT improves ventricular function by promoting angiogenesis through Rho/ROCK/ERK1/2 signal pathway in infarcted myocardium in rats

Abstract Objective This study aimed to investigate the effects of extracorporeal cardiac shock wave therapy (CSWT) on myocardial ischemia and cardiac function in rats with myocardial infarction, and to explore its impact on the expression of myocardial vascular endothelial growth factor and the extent of myocardial fibrosis, thereby elucidating the mechanism of angiogenesis. Methods A rat model of myocardial infarction was induced by ligating the left anterior descending branch of the coronary artery, confirmed by echocardiography. Animals were randomly assigned to five groups: sham operation group, myocardial infarction group, myocardial infarction + CSWT group, myocardial infarction + Y-27632 group, and myocardial infarction + CSWT + Y-27632 group. Cardiac function was evaluated by echocardiography on the 16th and 72nd day post-surgery. Myocardial morphology was assessed by HE staining, and the extent of myocardial fibrosis was determined by Masson's trichrome staining. Immunohistochemical staining for factor VIII was conducted to observe angiogenesis in each infarcted area. Western blotting was employed to detect the protein expression of extracellular regulated kinase (ERK1/2) and pro-angiogenic cytokines in the infarct border zone. Results CSWT treatment significantly reduced myocardial fibrosis and improved cardiac function compared to the myocardial infarction group. Additionally, CSWT upregulated ERK expression and angiogenesis-related factors, promoting angiogenesis. The beneficial effects of CSWT were abolished by inhibiting the Rho/ROCK/ERK1/2 pathway. Furthermore, the area of myocardial fibrosis was significantly reduced in the MI+Y-27632 group compared to the myocardial infarction group (p < 0.01), and left ventricular systolic function index was significantly higher in the myocardial infarction group. Conclusions CSWT may promote angiogenesis post-myocardial infarction by activating the Rho/ROCK/ERK1/2 pathway. Additionally, Y-27632 may improve cardiac function in rats with myocardial infarction, potentially through mitigating myocardial fibrosis.echo images of ratsprotein expression by WB

An analysis of magnetogasdynamic shock wave propagation in a rotational axisymmetric self-gravitating nonideal gas

An analysis of magnetogasdynamic shock wave propagation in a rotational axisymmetric self-gravitating nonideal gas

Numerical Investigation of Two-Phase Shock Waves in CO2 Flows Using a Modified Hertz–Knudsen Model

Abstract Understanding the complex behavior of two-phase shocks in CO2 flows is essential for a variety of applications, including carbon capture and storage () and transcritical refrigeration cycles. This study presents a comprehensive numerical investigation of two-phase shock waves using the multispecies user-defined real gas model in Ansys Fluent. The simulations are performed for de-Laval nozzles, exploring the two-phase shock features for three-dimensional (3D), two-dimensional (2D), and two-dimensional axisymmetric geometries. The nonequilibrium condensation, subsequent evaporation, and denucleation occurring across the shock are modeled through a set of user-defined scalar transport equations implemented within Ansys Fluent. The two-phase computational fluid dynamics (CFD) simulations are carried out in proximity to the critical point where real gas effects are relevant. The CO2 real gas properties are computed using an in-house Python code and integrated into the solver via user-defined functions as external look-up tables. This study provides valuable insights into the physical processes underlying two-phase shocks in CO2 flows and their sensitivity to geometric variations and thermodynamic conditions. The findings contribute to the development and modification of predictive models and optimized designs for systems involving two-phase CO2 flows. The results highlight the influence of geometry configurations and thermodynamic conditions on shock location and intensity, providing comparisons for shock waves occurring in two-phase flows and supercritical single-phase flows.

Quantifying motion blur by imaging shock front propagation with broadband and narrowband X-ray sources

Time-integrated radiography using MeV Bremsstrahlung X-ray sources is the norm for imaging during system-level testing of components and structures under dynamic condition. One source of error in the analysis of the time-integrated radiography data sets stems from motion blur which smears out sharp interfaces to a greater degree with longer exposure times, which become necessary to provide sufficient signal-to-noise with low X-ray penetration of objects of interest. To quantify motion blur, a 1D shock wave through PMMA was investigated experimentally at The Dynamic Compression Sector at The Advanced Photon Source (DCS@APS) with tapered broadband and 25.46 ± 1.06 keV narrowband X-rays. Four cameras with different exposure times were used for each experiment to compare the effect that exposure time has on motion blur. In addition, our methodology to accurately simulate motion blur in terms of transmission and shape is presented and compared to our experimental results and quantified. There is a high level of agreement between the experimental and simulation results across the range of data sets investigated in this study with a percent difference range of 0.29–1.31% for the four shots. The methodology of this work serves as a steppingstone towards a physically validated model that could be used in conjunction with experimental results to deconvolve physical parameters, densities, and interfaces of interest in a way that would not be possible with experimental results alone.

Investigating novel optical soliton solutions for a generalized (3+1)-dimensional q-deformed equation

In this study, we investigate the (3+1) q-deformed tanh-Gordon equation due to its importance in the context of mathematical physics. It describes solitonic solutions in quantum field theory; it can sometimes be used in condensed matter physics to describe interactions between particles in magnetic materials or superconductors; it can model light propagation in nonlinear optical fibers or photonic crystals where the refractive index has a q-deformed structure; and it also can be applied in studying shock waves, turbulence and rogue waves where the deformation introduces corrections to classical wave phenomena. Utilizing the (G′ωG′+G+r)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\frac{{\\mathfrak {G}}^{\\prime }}{\\omega {\\mathfrak {G}}^{\\prime }+{\\mathfrak {G}}+r})$$\\end{document}-expansion technique, we derive novel analytical solutions that enhance our understanding of the underlying dynamics. Additionally, we employ a finite element method (extended cubic B-spline method) to validate our analytical findings and explore the behavior of the q-deformed equation under different parameter regimes. Our results demonstrate the versatility of the q-deformed framework in generating rich optical phenomena, paving the way for future research in both theoretical and applied physics.

Phase transition in heterogeneous macro continuum model integrating the jerk effect with the mixed traffic flow involving human driving and ADAS vehicles

Vehicles equipped with advanced driving assistance systems (ADAS) can acquire information about preceding and following vehicles, which will have an undeniable impact on the phase transition of traffic flow. Therefore, we establish a new heterogeneous continuum model of traffic flow considering the jerk effect mixed with human driving (HD) and ADAS vehicles. The neutral stability condition associated with the permeability of ADAS vehicle is inferred via stability analysis. According to simulation, shock wave occurs, implying that our model can emerge correct wave propagation trend. Moreover, the simulation of density evolution and flow changes also suggests that an increase in ADAS vehicle penetration and jerk effect can enhance traffic system stability and reduce energy consumption.

A Nonlinear Approach in the Quantification of Numerical Uncertainty by High-Order Methods for Compressible Turbulence with Shocks

This is a comprehensive overview on our research work to link interdisciplinary modeling and simulation techniques to improve the predictability and reliability simulations (PARs) of compressible turbulence with shock waves for general audiences who are not familiar with our nonlinear approach. This focused nonlinear approach is to integrate our “nonlinear dynamical approach” with our “newly developed high order entropy-conserving, momentum-conserving and kinetic energy-preserving methods” in the quantification of numerical uncertainty in highly nonlinear flow simulations. The central issue is that the solution space of discrete genuinely nonlinear systems is much larger than that of the corresponding genuinely nonlinear continuous systems, thus obtaining numerical solutions that might not be solutions of the continuous systems. Traditional uncertainty quantification (UQ) approaches in numerical simulations commonly employ linearized analysis that might not provide the true behavior of genuinely nonlinear physical fluid flows. Due to the rapid development of high-performance computing, the last two decades have been an era when computation is ahead of analysis and when very large-scale practical computations are increasingly used in poorly understood multiscale data-limited complex nonlinear physical problems and non-traditional fields. This is compounded by the fact that the numerical schemes used in production computational fluid dynamics (CFD) computer codes often do not take into consideration the genuinely nonlinear behavior of numerical methods for more realistic modeling and simulations. Often, the numerical methods used might have been developed for weakly nonlinear flow or different flow types other than the flow being investigated. In addition, some of these methods are not discretely physics-preserving (structure-preserving); this includes but is not limited to entropy-conserving, momentum-conserving and kinetic energy-preserving methods. Employing theories of nonlinear dynamics to guide the construction of more appropriate, stable and accurate numerical methods could help, e.g., (a) delineate solutions of the discretized counterparts but not solutions of the governing equations; (b) prevent numerical chaos or numerical “turbulence” leading to FALSE predication of transition to turbulence; (c) provide more reliable numerical simulations of nonlinear fluid dynamical systems, especially by direct numerical simulations (DNS), large eddy simulations (LES) and implicit large eddy simulations (ILES) simulations; and (d) prevent incorrect computed shock speeds for problems containing stiff nonlinear source terms, if present. For computation intensive turbulent flows, the desirable methods should also be efficient and exhibit scalable parallelism for current high-performance computing. Selected numerical examples to illustrate the genuinely nonlinear behavior of numerical methods and our integrated approach to improve PARs are included.

Can extracorporeal shock wave therapy be effective in temporomandibular joint disorder?: A pilot study.

This study aimed to compare extracorporeal shock wave therapy (ESWT) with the use of stabilization splint in nonsurgical temporomandibular disorders treatments, and to evaluate the effects. In this study, individuals, who are diagnosed with disc displacements with reduction according to the diagnostic criteria for temporomandibular disorder examination criteria. The patients in the first control group (n = 36) were applied a medical treatment + stabilization splint. The second group (n = 25) was applied the ESWT (2 days a week for 4 weeks) + medical treatment + stabilization splint. Visual Analog Scale scores, painless maximum painless mouth opening, and passive-forced mouth opening measurements were recorded for the first and second weeks. The ESWT application significantly contributed to pain-reducing (Visual Analog Scale) in patients at short notice (P = .030) in the second group. There were statistically significant differences between the groups in painless maximum active mouth opening (P = .009) and passive forced measurements (P = .004) in the second week. This pilot study showed that short-term ESWT addition to stabilization splint and medical treatment may yield satisfactory outcomes.

Explicit exact solutions for plane shock waves in dilute polyatomic gases

AbstractThe exact solutions for the Navier–Stokes–Fourier equations in the case of plane shock waves for dilute monatomic gases with constant transport coefficients were found by Becker in 1922. The solutions obtained are limited for a Prandtl's number given by . Besides the solutions for the speed and temperature, profiles were given in an implicit way. In this paper, we consider Becker's model to find some exact explicit solutions for dilute polyatomic gases.

High-fidelity simulations of microramp-controlled shock wave/boundary layer interaction

Microvortex generators (MVGs) are a promising solution to control shock wave/turbulent boundary layer interactions (SBLIs), especially in supersonic inlets. In this study, we examine the effects of a microramp vortex generator on an SBLI generated by an oblique shock wave and a turbulent boundary layer using direct numerical simulations (DNSs). Two cases, with and without the presence of a microramp, are compared in terms of their mean and unsteady flow features at free-stream Mach number equal to 2 and friction Reynolds number at the inviscid shock impingement equal to 600. The long integration period allows us to assess how microramps affect the typical low-frequency unsteadiness observed in SBLIs, and the data generated may serve as a reference for simulations of lower fidelity or reduced order models. The analysis shows that the three-dimensional microramp wake alters the interaction region dramatically, inducing a significant spanwise modulation and topology change of the separation. For example, tornado-like structures redistribute the flow in both the spanwise and wall-normal directions inside the recirculation region. The increase in momentum close to the wall by the ramp vortices effectively delays the onset of the separation and, thus, the separation length, but at the same time leads to a significant increase in the intensity of the wall-pressure fluctuations. We then characterise the mutual interaction between the arch-like vortices around the ramp wake and the SBLI. The specific spanwise vorticity shows that these vortices follow the edge of the separation and their intensity, apart from mean compressibility effects, is not affected by the shocks. The shocks, instead, are deformed in shape by the periodic impingement of the vortices, although the spectral analysis did not reveal any significant trace of their shedding frequency in the separation region. These Kelvin–Helmholtz vortices, however, may be relevant in the closure of the separation bubble. Fourier analysis also shows a constant increase, in both value and magnitude, in the low-frequency peak all along the span, suggesting that the motion of the separation shock remains coherent while being disturbed by the arch-like vortices and oscillating at a higher frequency in absolute terms.

The lack of floater perception in eyes with asteroid hyalosis and its direct implications on laser vitreolysis

PurposeTo present a novel optical model explaining why the vast majority of patients with Asteroid Hyalosis (AH) do not perceive any floaters. This changes our understanding of floater perception and undermines the operation mode of YAG laser vitreolysis.MethodsRelying on a previously published model of floater perception based on astronomical equations of a solar eclipse, and on ultrasound images of the vitreous in three eyes with AH, we explain why such patients do not perceive floaters in spite of opaque bodies filling their entire vitreous, to the point of, in severe cases of AH, obscuring the fundus view during ophthalmoscopy.Main outcome measuresDeveloping an optical model of light rays that can quantify the maximal distance upon which a vitreous floater or opacity will cast a shadow on the retina.ResultsCalculations using the proposed model demonstrated that with a 3 mm pupil, for a floater located between 1.5 mm and 2 mm from the retina, its shortest diameter must be > 215 microns and > 286 microns, respectively, to be perceived. Since AH floaters, based on ultrasound imaging, do not exist in the most peripheral 1.5 mm of the vitreous, it becomes understandable why these patients are asymptomatic.ConclusionsBased on the proposed model and our findings, we deduced that even large, degenerative floaters whose width is usually narrower than a large retinal vein (125 microns), must be located very close to the retina and hence are not the floaters that are aimed at when performing YAG laser vitreolysis. We speculate that in successful cases, YAG vitreolysis works by a different mechanism, most likely a shock wave that displaces floaters further away from the retina. Hence, vitreolysis might not necessarily require the laser be aimed at the floaters, as symptomatic floaters may be located in the outer 1.5–2.0 mm of the vitreous body, a very risky zone for YAG laser shots.

Inactivation of MS-2 virus in water by rotational generator of hydraulic shock

This study investigates the effect of hydraulic shock waves on inactivation of MS-2 bacteriophage, a norovirus surrogate. A falling circular jet of water spiked with the MS-2 (∼1000 PFU/mL) was repeatedly impacted by a rotating blade, resulting in occurrence of hydraulic shock waves within the liquid region adjacent to the impact. The proof-of-concept rotational generator of hydraulic shock treating 9 L of water spiked with viruses was able to achieve 3 logs reduction of viral plaque count within 80–100 liquid passes at moderate blade impact velocities (namely, 70 and 88 m/s) despite the water temperature not exceeding 40 °C and no detectible cavitation. Within the first 20 liquid passes, most MS-2 capsid proteins were degraded, with their concentration reduced from 22 μg/mL to only 7.3 μg/mL. Due to the lack of further capsid protein destruction, additional reduction in MS-2 plaque count in subsequent 80 passes is indicative of damage inflicted to the viral recognition receptors. All this suggests that shockwaves of moderate amplitude (few tens of MPa) alone are sufficient for effective viral inactivation. Considering this and the device's good scalability potential, rotational hydraulic shock generators could prove effective in treating virus-contaminated waters.

Directional enhancement of underwater impact and bubble loads in neighbor two-phase fluid domains charge

The loading characteristics of underwater explosions and the dynamic behavior of bubbles are directly related to the charge structure. This study proposes a unique charge structure in a gas–liquid two-phase fluid domain. Numerical methods are used to investigate the effects of fluid layer thickness and gas–liquid ratio on underwater explosion shock wave load, bubble dynamics, and bubble pulsation load. The results show that the two-phase fluid layer significantly enhances the directional release of shock wave energy and bubble pulsation load. During the shock wave phase, a lagging wave effect appears in the liquid layer direction, causing a secondary high-energy shock, significantly increasing the specific impulse. The gas layer direction may form a pressure relief channel effect, enhancing the shock wave peak pressure. For the bubble motion phase, differences in the physical properties of the fluid layer medium lead to irregular bubble boundary movements, promoting bubble tearing and rupture. The gaseous medium converts the accumulated shock wave energy into the internal energy of the bubble, increasing its volume potential. Although this characteristic reduces the pulsation frequency, it significantly increases the specific impulse. Altering the fluid layer medium can control explosion loads and bubble movement, offering new insights for ocean engineering applications.

Explosive characteristics of premixed hydrogen-air subjected to various concentration gradients

In this research, different concentrations of hydrogen-air were charged into separate compartments of a 4.7 m pipe with a circular cross-section. The high-speed laser schlieren technique and overpressure detection technique were employed to accurately acquire the kinetic parameters of the explosive flow field, i.e., the evolution of the flame morphology, the flame propagation velocity and the shock wave overpressure. Two concentration gradients of 15 %-17 % and 15 %-25 % were programmed for the experiment. Affected by R-T, D-L, and multidimensional shock wave perturbations, the flame morphology exhibits fingertip, planar, cellular, tulip, and twisted tulip structures. Prolonging the gas diffusion time, the mean flame speeds were observed to be 10 m/s and 20 m/s after 10 min of diffusion for 15 %-17 % and 15 %-25 %, respectively, smaller than 45 m/s and 150 m/s at uniform concentrations. Besides, with the prolongation of diffusion time, the flame rarely backflows, and the velocity is more homogeneous and stable. Furthermore, as the ignition position approaches the concentration gradient, the flame is “driven” by the reflected shock wave upstream coupled with the effect of the elevated gas concentration, which significantly enhances the propagation velocity and overpressure.

Point-enhanced convolutional neural network: A novel deep learning method for transonic wall-bounded flows

Low order models can be used to accelerate engineering design processes. Ideally, these surrogates should meet the conflicting requirements of large design space coverage, high accuracy and fast evaluation. Within the context of aerospace applications at transonic conditions, this can be challenging due to the associated non-linearity of the flow regime. Different methods have been investigated in the past to predict the flow-field around shapes such as airfoils or cylinders. However, they usually have reduced spatial resolution, limiting the prediction capabilities within the boundary layer which is of interest for transonic wall-bounded flows. This work proposes a novel Point-Enhanced Convolutional Neural Network (PCNN) method that combines the advantages of the well-established PointNet and convolutional neural network approaches. The PCNN model has relatively low memory requirements in the training process, preserves the spatial correlation in the domain and has the same resolution as a traditional computational method. The architecture is used for the flow-field prediction of civil aero-engine nacelles in which it is demonstrated that the flow features of peak isentropic Mach number (Mis), pre-shock isentropic Mach number and shock location (X/Lnac) are captured within ΔMis = 0.02, ΔMis=0.04, ΔX/Lnac=0.007, respectively. The PCNN model successfully predicts the integral parameters of the boundary layer, in which the incompressible displacement thickness, momentum thickness and shape factor are typically within 5% of the CFD. Overall, the PCNN method is demonstrated for transonic wall-bounded flows for a range of flow physics that include shock waves and shock-induced separation.

Hydrodynamics of a discrete conservation law

AbstractThe Riemann problem for the discrete conservation law is classified using Whitham modulation theory, a quasi‐continuum approximation, and numerical simulations. A surprisingly elaborate set of solutions to this simple discrete regularization of the inviscid Burgers' equation is obtained. In addition to discrete analogs of well‐known dispersive hydrodynamic solutions—rarefaction waves (RWs) and dispersive shock waves (DSWs)—additional unsteady solution families and finite‐time blowup are observed. Two solution types exhibit no known conservative continuum correlates: (i) a counterpropagating DSW and RW solution separated by a symmetric, stationary shock and (ii) an unsteady shock emitting two counterpropagating periodic wavetrains with the same frequency connected to a partial DSW or an RW. Another class of solutions called traveling DSWs, (iii), consists of a partial DSW connected to a traveling wave comprised of a periodic wavetrain with a rapid transition to a constant. Portions of solutions (ii) and (iii) are interpreted as shock solutions of the Whitham modulation equations.

Effects of discharge parameters on plasma acceleration and transmission characteristics of a coaxial gun operated in gas-prefilled mode

The effects of discharge parameters on the discharge process and plasma transport characteristics of a coaxial gun in the gas-prefilled mode are studied. The plasma optical intensity and ejection velocity are measured by photodiodes, the optical emission spectrum is taken by a spectroscopic system, and the plasma evolution in the transport process is captured by a high-speed camera. The plasma acceleration characteristics under different discharge parameters show that the velocity and electron density of the ejection plasma are mainly determined by the pre-filled pressure and discharge current, which is consistent with the snowplow model. The kinetic energy of ejection plasma can be significantly increased by reducing the outer loop inductance, which is conducive to increasing the energy utilization efficiency. The time-varying images of plasma radiation and the plasma density at different transport locations illuminate the transmission characteristics of coaxial gun discharge plasma. The results show that the snowplow effect continues to play a role in the plasma transport process, and the plasma accumulation is induced by the combination of shock wave compression. The current-driven magneto hydrodynamics instability occurs during the transport process, and the luminous signal of the plasma current sheet oscillates periodically. In addition, the plasma impact effect is obvious and the gas retarding effect is enhanced with the increase in the gas pressure. These results give us a more comprehensive view of the coaxial gun discharge process and plasma transport and provide a certain reference for optimizing the parameters selection and physical design of coaxial gun discharge plasma characteristics.