Diagnosis and laparoscopic excision of accessory cavitated uterine mass in a young woman:A case report

BACKGROUND Accessory and cavitated uterine mass(ACUM)is an uncommon form of connate Müllerian anomaly seen in young and nulliparous women,which presents as chronic periodic pelvic pain and severe dysmenorrhea.The entity is often underdiagnosed due to a broad differential diagnosis,including rudimentary uterine horn,true cavitated adenomyosis and degenerating fibroids.CASE SUMMARY A 22-year-old woman who presented with severe dysmenorrhea and was initially misdiagnosed with cystic adenomyosis.Gynecological examination and ultrasonography were performed.The patient underwent laparoscopic excision of the mass and histopathological examination confirmed the diagnosis.Postoperatively,the patient did well,with no further dysmenorrhea.CONCLUSION ACUM is difficult to diagnose.A correct diagnosis can be made only after excision and histopathological evaluation.Surgical excision is necessary and can be carried out by laparoscopy.

QUALITATIVE STUDY OF CAVITATED BIFURCATION FOR A CLASS OF INCOMPRESSIBLE GENERALIZED NEO-HOOKEAN SPHERES

The problem of spherical cavitated bifurcation was examined for a class of incompressible generalized neo-Hookean materials, in which the materials may be viewed as the homogeneous incompressible isotropic neo-Hookean material with radial perturbations. The condition of void nucleation for this problem was obtained. In contrast to the situation for a homogeneous isotropic neo-Hookean sphere, it is shown that not only there exists a secondary turning bifurcation point on the cavitated bifurcation solution which bifurcates locally to the left from trivial solution, and also the critical load is smaller than that for the material with no perturbations, as the parameters belong to some regions. It is proved that the cavitated bifurcation equation is equivalent to a class of normal forms with single-sided constraints near the critical point by using singularity theory. The stability of solutions and the actual stable equilibrium state were discussed respectively by using the minimal potential energy principle.

Investigation of hydroxyl-terminated polybutadiene propellant breaking characteristics and mechanism impacted by submerged cavitation water jet

A submerged cavitation water jet(SCWJ)is an effective method to recycle solid propellant from obsolete solid engines by the breaking method.Solid propellant's breaking modes and mechanical process under SCWJ impact are unclear.This study aims to understand those impact breaking mechanisms.The hydroxyl-terminated polybutadiene(HTPB)propellant was chosen as the research material,and a self-designed test system was used to conduct impact tests at four different working pressures.The high-speed camera characterized crack propagation,and the DIC method calculated strain change during the impact process.Besides,micro and macro fracture morphologies were characterized by scanning electron microscope(SEM)and computed tomography(CT)scanning.The results reveal that the compressive strain concentration region locates right below the nozzle,and the shear strain region distributes symmetrically with the jet axis,which increases to 4% at first 16th ms,the compressive strain rises to 2% and 6% in the axial and transverse direction,respectively.The two tensile cracks formed first at the compression strain concentrate region,and there generate many shear cracks around the tensile cracks,and those shear cracks that develop and aggregate cause the cracks to become wider and cut through the tensile cracks,forming the tensile-shear cracks and the impact parts eventually fail.The HTPB propellant forms a breaking hole shaped conical after impact 10 s.The mass loss increases by 17 times at maximum,with the working pressure increasing by three times.Meanwhile,the damage value of the breaking hole remaining on the surface increases by 7.8 times while 2.9 times in the depth of the breaking hole.The breaking efficiency is closely affected by working pressures.The failure modes of HTPB impacted by SCWJ are classified as tensile crack-dominated and tensile-shear crack-dominated damage mechanisms.

超声空化在船舶与海洋工程中的应用

Biofouling on ships and offshore structures has always been a difficult problem to solve,which not only jeopardizes the structural strength but also brings great economic losses.Ultrasonic cavitation is expected to solve this problem due to its characteristics of no damage to structures and no pollution.Starting from the phenomenon and mechanism of ultrasonic cleaning,this paper introduces the application of ultrasonic cavitation in ship,pipeline and oil cleaning as well as ballast water treatment.By reviewing the existing studies,limitations such as insufficient ultrasonic parameter studies,lack of uniform cleanliness standards,and insufficient cavitation studies are summarized to provide traceable research ideas for improving ultrasonic cavitation technology and to guide the expansion and improvement of its applications.

Experimental and Numerical Evaluation of the Cavitation Performances of Self-Excited Oscillating Jets

Self-excited oscillating jets(SOJ)are used in several practical applications.Their performances are significantly affected by structural parameters and the target distance.In this study,a geometric model of the SOJ nozzle accounting for multiple structural parameters is introduced,then the related cavitation performances and the optimal target distance are investigated using a Large-Eddy Simulation(LES)approach.Results are also provided about an experiment,which was conducted to validate the simulation results.By analyzing the evolution of the vapor volume fraction at the nozzle outlet,a discussion is presented about the effect of the aforementioned structural parameters on the cavitation performances and the target distance.It is shown that the distribution of cavitation clouds at the outlet of the SOJ nozzle displays a non-monotonic trend(first increasing,then decreasing).Under working conditions with an inlet pressure of 4 MPa,a SOJ nozzle outlet/inlet diameter ratio(D_(1)/D_(2))of 1.2,and a chamber diameter ratio(D/L)close to 1.8,the nozzle outlet cavitation performance attains a maximum.The optimal structural parameters correspond to the optimal target distance,which is near 50 mm.The experiments have revealed that the SOJ nozzle with the above parameters displays a good cavitation erosion effect at the target distance of 50 mm,in satisfactory agreement with the numerical simulation results.

高马赫数球状气泡动力学理论研究

The compressibility of fluids has a profound influence on oscillating bubble dynamics,as characterized by the Mach number.However,current theoretical frameworks for bubbles,whether at the first or second order of the Mach number,are primarily confined to scenarios characterized by weak compressibility.Thus,a critical need to elucidate the precise range of applicability for both first-and second-order bubble theories arises.Herein,we investigate the suitability and constraints of bubble theories with different orders through a comparative analysis involving experimental data and numerical simulations.The focal point of our investigation encompasses theories such as the Rayleigh–Plesset,Keller,Herring,and second-order bubble equations.Furthermore,the impact of parameters inherent in the second-order equations is examined.For spherical oscillating bubble dynamics in a free field,our findings reveal that the first-and second-order bubble theories are applicable when Ma≤0.3 and 0.4,respectively.For a single sonoluminescence bubble,we define an instantaneous Mach number,Mai.The second-order theory shows abnormal sensibility when Mai is high,which is negligible when Mai≤0.4.The results of this study can serve as a valuable reference for studying compressible bubble dynamics.

Research on Cavitation Characteristics and Influencing Factors of Herringbone Gear Pump

Cavitation is a common issue in pumps,causing a decrease in pump head,a fall in volumetric efficiency,and an intensification of outlet flow pulsation.It is one of the main hazards that affect the regular operation of the pump.Research on pump cavitation mainly focuses on mixed flow pumps,jet pumps,external spur gear pumps,etc.However,there are few cavitation studies on external herringbone gear pumps.In addition,pumps with different working principles significantly differ in the flow and complexity of the internal flow field.Therefore,it is urgent to study the cavitation characteristics of external herringbone gear pumps.Compared with experimentalmethods,visual research and cavitation area identification are achieved through computation fluid dynamic(CFD),and changing the boundary conditions and shape of the gear rotor is easier.The simulation yields a head error of only 0.003%under different grid numbers,and the deviation between experimental and simulation results is less than 5%.The study revealed that cavitation causes flow pulsation at the outlet,and the cavitation serious area is mainly distributed in the meshing gap and meshing area.Cavitation can be inhibited by reducing the speed,increasing the inlet pressure,and changing the helix angle can be achieved.For example,when the inlet pressure is 5 bar,the maximumgas volume fraction in themeshing area is less than 50%.These results provide a reference for optimizing the design and finding the optimal design parameters to reduce or eliminate cavitation.

Numerical Investigation of the Angle of Attack Effect on Cloud Cavitation Flow around a Clark-Y Hydrofoil

Cavitation is a prevalent phenomenon within the domain of ship and ocean engineering,predominantly occurring in the tail flow fields of high-speed rotating propellers and on the surfaces of high-speed underwater vehicles.The re-entrant jet and compression wave resulting from the collapse of cavity vapour are pivotal factors contributing to cavity instability.Concurrently,these phenomena significantly modulate the evolution of cavitation flow.In this paper,numerical investigations into cloud cavitation over a Clark-Y hydrofoil were conducted,utilizing the Large Eddy Simulation(LES)turbulence model and the Volume of Fluid(VOF)method within the OpenFOAM framework.Comparative analysis of results obtained at different angles of attack is undertaken.A discernible augmentation in cavity thickness is observed concomitant with the escalation in attack angle,alongside a progressive intensification in pressure at the leading edge of the hydrofoil,contributing to the suction force.These results can serve as a fundamental point of reference for gaining a deeper comprehension of cloud cavitation dynamics.

Hydrodynamic Cavitation Enhanced SR-Aops Degradation of Organic Pollutants in Water:A Review

SR-AOP(sulfate radical advanced oxidation process)is a novel water treatment method able to eliminate refractory organic pollutants.Hydrodynamic cavitation(HC)is a novel green technology,that can effectively produce strong oxidizing sulfate radicals.This paper presents a comprehensive review of the research advancements in these fields and a critical discussion of the principal factors influencing HC-enhanced SR-AOP and the mechanisms of synergistic degradation.Furthermore,some insights into the industrial application of HC/PS are also provided.Current research shows that this technology is feasible at the laboratory stage,but its application on larger scales requires further understanding and exploration.In this review,some attention is also paid to the design of the hydrodynamic cavitation reactor and the related operating parameters.

Behaviors of cavitation bubbles driven by high-intensity ultrasound

In a multi-bubble system, the bubble behavior is modulated by the primary acoustic field and the secondary acoustic field. To explore the translational motion of bubbles in cavitation liquids containing high-concentration cavitation nuclei,evolutions of bubbles are recorded by a high-speed camera, and translational trajectories of several representative bubbles are traced. It is found that translational motion of bubbles is always accompanied by the fragmentation and coalescence of bubbles, and for bubbles smaller than 10 μm, the possibility of bubble coalescence is enhanced when the spacing of bubbles is less than 30 μm. The measured signals and their spectra show the presence of strong negative pressure, broadband noise,and various harmonics, which implies that multiple interactions of bubbles appear in the region of high-intensity cavitation.Due to the strong coupling effect, the interaction between bubbles is random. A simplified triple-bubble model is developed to explore the interaction patterns of bubbles affected by the surrounding bubbles. Patterns of bubble interaction, such as attraction, repulsion, stable spacing, and rebound of bubbles, can be predicted by the theoretical analysis, and the obtained results are in good agreement with experimental observations. Mass exchange between the liquid and bubbles as well as absorption in the cavitation nuclei also plays an important role in multi-bubble cavitation, which may account for the weakening of the radial oscillations of bubbles.

Morphological analysis for thermodynamics of cavitation collapse near fractal solid wall

A fractal geometric boundary with natural wall features is introduced into a hybrid lattice-Boltzmann-method(LBM)multiphase model. The physical model of cavitation bubble collapse near the irregular geometric wall is established to study the thermodynamic characteristics of the bubble collapse. Due to the lack of periodicity, symmetry, spatial uniformity and obvious correlation in the LBM simulation of the bubble collapse near the fractal wall, the morphological analysis based on Minkowski functional is introduced into the thermodynamic investigation of cavitation bubble so as to analyze and obtain the effective information. The results show that the Minkowski functional method can employed to study the temperature information in complex physical fields hierarchically and quantitatively. The high/low temperature region of the cavitation flow is explored, and thermal effect between irregular and fractal geometric wall and cavitation bubble can be revealed. It illustrates that LBM and morphological analysis complement each other, and morphological analysis can also be used as an optional and potential tool in research field of complex multiphase flows.

Investigation of Cavitation in NaCl Solutions in a Sonochemical Reactor Using the Foil Test Method

Ultrasonic baths and sonochemical reactors are widely used in industrial applications dealing with surface cleaningand chemical synthesis. The processes of erosion, cleaning and structuring of the surface can be typically controlledby changing relevant influential parameters. In particular, in this work, we experimentally investigate theeffect of NaCl concentration (0–5.5 mol/L) on the erosion of an aluminum foil under ultrasonic exposure at afrequency of 28 kHz. Special attention is paid to the determination of cavitation zones and their visualizationusing heat maps. It is found that at low NaCl concentration (0.3 mol/L), the foil destruction rate is higher thanin distilled water. At higher concentrations of salt, cavitation takes place mainly in the upper part of the container.

A Numerical Investigation of the Effect of Boundary Conditions on Acoustic Pressure Distribution in a Sonochemical Reactor Chamber

The intensification of physicochemical processes in the sonochemical reactor chamber is widely used in problems of synthesis,extraction and separation.One of the most important mechanisms at play in such processes is the acoustic cavitation due to the non-uniform distribution of acoustic pressure in the chamber.Cavitation has a strong impact on the surface degradation mechanisms.In this work,a numerical calculation of the acoustic pressure distribution inside the reactor chamber was performed using COMSOL Multiphysics.The numerical results have revealed the dependence of the structure of the acoustic pressure field on the boundary conditions for various thicknesses of the piezoelectric transducer.In particular,the amplitude of the acoustic pressure is minimal in the case of absorbing boundaries,and the attenuation becomes more significant as the thickness of the piezoelectric transducer increases.In addition,reflective boundaries play a significant role in the formation and distribution of zones of maximum cavitation activity.

Jet Characteristics and Optimization of a Cavitation Nozzle for Hydraulic Fracturing Applications

Hydraulic jetting is a form of fracturing that involves using a high-pressure jet of water to create fractures in the reservoir rock with a nozzle serving as the central component of the hydraulic sandblasting perforation tool.In this study,the flow behavior of the nozzle is simulated numerically in the framework of a SST k-ωturbulence model.The results show that the nozzle structure can significantly influence the jet performance and related cavitation effect.Through orthogonal experiments,the nozzle geometric parameters are optimized,and the following configuration is found accordingly:contraction angle 20°,contraction segment length 6 mm,cylindrical segment diameter 6 mm,cylindrical segment length 12 mm,spread segment length 10 mm,and spread angle 55°.

A numerical analysis of the influence of the cavitator's deflection angle on flow features for a free moving supercavitated vehicle

When a high-speed cavitated weapon moves under water, the flow properties are important issues for the sake of the trajectory predication and control. In this paper, a single-fluid multiphase flow method coupled with a natural cavitation model is proposed to numerically simulate the flee moving phase of an underwater supercavitated vehicle under the action of the external thrust. The influence of the cavitator＇s deflection angle ranging from -3~ to 3~ on the cavity pattern, the hydrodynamics and the underwater trajectory is investigated. Based on computational results, several conclusions are qualitatively drawn by an analysis. The deflection angle has very little effect on the cavity pattern. When the deflection angle increases, the variation curves of the vertical linear velocity, the lift coefficient and the pitching moment coefficient become flatter. In the phase of the second natural cavitation, at a same time, the greater the deflection angle is, the lower the drag and the lift coefficients will be and the higher the pitching moment coefficient becomes. At the finishing time of the free moving phase, when the deflection angle lies in the small range of -1~ - 1~, the position of the center of mass and the pitching angle of the vehicle are more close to each other. However, when the deflection angle is less than -1° or greater than 1°, the position of the center of mass and the pitching angle change greatly. Ifa proper deflection angle of the cavitator is adopted, the underwater vehicle can navigate in a pseudo-fixed depth.

Effect of surface damage induced by cavitation erosion on pitting and passive behaviors of 304L stainless steel

The corrosion behavior of 304L stainless steel(SS)in 3.5wt%NaCl solution after different cavitation erosion(CE)times was mainly evaluated using electrochemical noise and potentiostatic polarization techniques.It was found that the antagonism effect resulting in the passivation and depassivation of 304L SS had significant distinctions at different CE periods.The passive behavior was predominant during the incubation period of CE where the metastable pitting initiated at the surface of 304L SS.Over the rising period of CE,the 304L SS experienced a transition from passivation to depassivation,leading to the massive growth of metastable pitting and stable pitting.The depassivation of304L SS was found to be dominant at the stable period of CE where serious localized corrosion occurred.

Structure optimization of the organ-pipe cavitating nozzle and its erosion ability test on hydrate-bearing sediments

Cavitating jet is a promising drilling rate improvement technology in both the marine natural gas hydrate (NGH) fluidization exploitation method and the integrated radial jet drilling and completion method. In present study, we aim to improve the efficiency of jet erosion and extracting NGH. With a computational fluid dynamics (CFD) method, the pressure, velocity and cavitation field characteristics of organ-pipe cavitating jet (OPCJ) are analysed. The divergent angle, throat length, and divergent length of OPCJ nozzle are preferred to obtain stronger jet cavitation erosion effect. Laboratory experiments of gas hydrate-bearing sediments (GHBS) erosion by OPCJ and conical jet (CJ) are conducted to compare and validate the jet erosion performance. The impinging models of OPCJ and CJ are constructed to study the impact characteristics. Results show that the preferred values of divergent angle, throat length, and divergent length are 15°, 1d, and 3d, respectively, in present simulation conditions. For GHBS, the OPCJ possesses the advantages of high efficiency and low energy consumption. Moreover, the OPCJ has higher penetration efficiency, while showing equivalent penetration ability compared to CJ. During the impinging process, the OPCJ can induce stronger impact pressure and turbulence effect, and also shows stronger chambering effect and bottom cleaning ability compared to CJ. This study presents the erosion performance of OPCJ and CJ on GHBS, and provides preliminary insights on the potential field applications in NGH exploitation.

Generation and Evolution of Cavitation Bubbles in Volume Alternate Cavitation(VAC)

Cavitation generation methods have been used in multifarious directions because of their diversity,and numerous studies and discussions have been conducted on cavitation generation methods.This study aims to explore the generating mechanism and evolution law of volume alternate cavitation(VAC).In the VAC,liquid water is placed in an airtight container with a variable volume.As the volume alternately changes,the liquid water inside the container continues to cavitate.Then,the mixture turbulence model and in-cylinder dynamic grid model are adopted to conduct computational fluid dynamics simulation of volume alternate cavitation.In the simulation,the cloud images at seven heights on the central axis are monitored,and the phenomenon and mechanism of height and eccentricity are analyzed in detail.By employing the cavitation flow visualization method,the generating mechanism and evolution law of cavitation are revealed.The synergistic effects of experiments and high-speed camera capturing confirm the correctness of the simulation results.In the experiment,the volume change stroke of the airtight container is set to 20 mm,the volume change frequency is 18 Hz,and the shooting frequency of the high-speed camera is set to 10000 FPS.The experimental results indicate that the position of the cavitation phenomenon has a reasonable law during the whole evolution cycle of the cavitation cloud.Also,the volume alternation cycle corresponds to the generation,development,and collapse stages of cavitation bubbles.

Experimental Study on Ultrasonic Cavitation Intensity Based on Fluorescence Analysis

The Ultrasonic cavitation effect has been widely used in mechanical engineering,chemical engineering,biomedicine,and many other fields.The quantitative characterization of ultrasonic cavitation intensity has always been a difficulty.Based on this,a fluorescence analysis method has been adopted to explore ultrasonic cavitation intensity in this paper.In the experiment of fluorescence intensity measurement,terephthalic acid(TA)was used as the fluorescent probe,ultrasonic power,ultrasonic frequency,and irradiation time were independent variables,and fluorescence intensity and fluorescence peak area were used as experimental results.The collapse of cavitation bubble will cause molecular bond breakage and release·OH,and the non-fluorescent substance TA will form the strong fluorescent substance TAOH with·OH.The spectra of the treated samples were measured by a F-7000 fluorescence spectrophotometer.The results showed that the fluorescence intensity and fluorescence peak area increased rapidly after ultrasonic cavitation treatment,and then increased slowly with the increase of ultrasonic power,which gradually increased with the increase of irradiation time.They first decreased and then increased with the increase of ultrasonic frequency from 20 kHz to 40 kHz.The irradiation time was the most influential factor,and the cavitation intensity of low frequency was higher overall.The fluorescence intensity and fluorescence peak area of the samples increased by 2-20 times after ultrasonic treatment,which could increase from 69 and 5238 to 1387 and 95451,respectively.After the irradiation time exceeded 25 min,the growth rate of fluorescence intensity slowed down,which was caused by the decrease of gas content and TA concentration in the solution.The study quantitatively characterized the cavitation intensity,reflecting the advantages of fluorescence analysis,and provided a basis for the further study of ultra-sonic cavitation.

半悬挂扭曲舵水动力及空化性能研究

In this study,we designed a new,semi-balanced,twisted rudder to reduce the surface cavitation problem of medium-high-speed surface warships.Based on the detached eddy simulation(DES)with the Spalart-Allmaras(SA)model(SA-DES)and the volume of fluid(VOF)method,the hydrodynamic and cavitation performances of an ordinary semi-balanced rudder and semi-balanced twisted rudder at different rudder angles were numerically calculated and compared using the commercial computational fluid dynamics(CFD)software STAR-CCM+with the whole-domain structured grid.The calculation results showed that,under the same working conditions,the maneuverability of the semi-balanced twisted rudder basically remained unchanged compared with that of the ordinary semi-balanced rudder.Furthermore,the surface cavitation range of the semi-balanced twisted rudder was much smaller,and the inception rudder angle of the rudder surface cavitation increased by at least 5°at the maximum speed.In conclusion,the semi-balanced twisted rudder effectively reduced the cavitation of the rudder surface without reducing the rudder effect and exhibited excellent anti-cavitation performance.