Optimizing lavage during knee arthroscopy: A three‐dimensional MRI study

A numerical study on differences in using Navier–Stokes and Reynolds equations for modeling the fluid flow and particle transport in single rock fractures with shear

Constant extension rate tensile (CERT) tests are traditionally used to understand the influence of material composition, heat treatment, temperature and environmental variables on stress corrosion crack (SCC) initiation. However, fluid flow rate has not been investigated as a parameter that could affect SCC initiation until recently. These studies have exhibited longer time to failure under high flow conditions indicating delayed crack initiation. Because these experiments have been performed in highly oxygenated water, no correlation has been established between the influence of flow velocity on the electrochemical corrosion potential (ECP) and the time to failure of tensile test specimens. The interrelationship between the fluid flow velocity, ECP and the time to failure is of great interest to the Boiling Water Reactor (BWR) applications primarily because of the previous observations that the ECP of Type 304 stainless steel increases with fluid flow velocity. This paper describes an attempt that has been made to understand the interrelationship between fluid flow velocity, ECP and the time for crack initiation in high temperature high purity water simulating both the BWR chemistry and the component flow velocity conditions. The range of flow velocities employed in the present study was 0.002 to 2 ft/s. The studies indicate that while high flow velocities can increase ECP there is a delayed effect on crack initiation.

A simply supported pipe conveying fluid and two moving masses upon it constitute this nitration system. The equation of motion is derived by using Lagrange's equation. The influence of the velocities of two moving masses, the distance between two moving masses, and the velocities of fluid flow in the pipe have been studied on the dynamic behavior of a simply supported pipe by numerical method. The velocities of fluid flow are considered with in its critical values of a simply supported pipe without moving masses upon It. Their coupling effects on the transverse vibration of a simply supported pipe are inspected too. As the velocity of two moving masses increases, the deflection of a simply supported pipe is increased and the frequency of transverse vibration of a simply supported pipe is not varied. In case of small distance between two masses, the maximum deflection of the pipe occur when the front mass arrive at midspan. Otherwise as the distance get larger, the position of the front masses where midspan deflection is maximum moves beyond the midpoint of a simply supported pipe. The deflection of a simply supported pipe is increased by coupling of the velocities of moving masses and fluid flow.

The interplay between compaction‐driven fluid flow and plastic yielding within porous media is investigated through numerical modeling. We establish a framework for understanding the dynamics of fluid flow in deforming porous materials that corresponds to the equations describing solitary porosity wave propagation. A concise derivation of the coupled fluid flow and poro‐viscoelastoplastic matrix behavior is presented, revealing a connection to Biot's equations of poroelasticity and Gassmann's theory in the elastic limit. Our findings demonstrate that fluid overpressure resulting from channelized fluid flow initiates the formation of new shear zones. Through three‐dimensional simulations, we observe that the newly formed shear zones exhibit a parabolic shape. Furthermore, plasticity exerts a significant influence on both the velocity of fluid flow and the shape of fluid channels. Importantly, our study highlights the potential of spontaneous channeling of porous fluids to trigger seismic events by activating both new and pre‐existing faults.

The Vortex Induced Vibration (VIV) phenomenon leads to mechanical issues concerning bluff bodies immerged in fluid flows and have therefore been studied by numerous authors. Moreover, an increasing demand for energy implies the development of alternative, complementary and renewable energy solutions. The main idea of EauVIV project consists in the use of VIV rather than its deletion.When rounded objects are immerged in a fluid flow, vortices are formed and shed on their downstream side, creating a pressure imbalance resulting in an oscillatory lift. A convertor modulus consists of an elastically mounted, rigid cylinder on end-springs, undergoing flow- induced motion when exposed to transverse fluid-flow. These vortices induce cyclic lift forces in opposite directions on the circular bar and cause the cylinder to vibrate up and down. An experimental prototype was developed and tested in a free-surface water channel and is already able to recover energy from free-stream velocity between 0.5 and 1 m.s-1. However, the large number of parameters (stiffness, damping coefficient, velocity of fluid flow, etc.) associated with its performances requires optimization and we choose to develop a complete tridimensionnal numerical model solution.A 3D numerical model has been developed in order to represent the real system behavior and improve it through, for example, the addition of parallel cylinders. The numerical model build up was carried out in three phases. The first phase consists in establishing a 2D model to choose the turbulence model and quantify the dependence of the oscillations amplitudes on the mesh size. The second corresponds to a 3D simulation with cylinder at rest in first time and with vertical oscillation in a second time. The third and final phase consists in a comparison between the experimental system dynamic behavior and its numerical model.

An analytical solution is given for the eigenfrequencies of the vibrations of a generally orthotropic plate placed in a rigid channel of rectangular cross section through which fluid flows. The fluid flow, assumed to be inviscid, compressible and non-steady, is modeled using a linearized potential equation. The plate is simply supported along the channel and extends indefinitely; its vibrations are also assumed to be linear. The resulting system of partial differential equations are simplified assuming a travelling wave mode along the plate. The problem is reduced to a single integro-differential equation and solved analytically to obtain an algebraic eigenvalue equation relating travelling wavespeed to wavelength and the velocity of fluid flow. It is found that, for the case of a composite plate within a duct, placing the strengthening fibers perpendicular to flow direction increases the minimum velocity at which the unstable oscillations will occur in most cases.

With the increase of the capacity of a fully air-cooled hydro-generator, the electromagnetic and thermal designs of such machine face more and more pressure. To ensure the reliability of a large hydro-generator, the thermal issue in rotor should be emphasized. In this paper, the temperature distribution in exciting windings and the fluid flowing between rotor poles are highlighted and investigated. Taking a 250 MW fully air-cooled large hydro-generator as an example, a three-dimensional solid–fluid heat transfer coupling model of the fluid and temperature was established, which includes half-axial rotors, two poles in circumferential direction, and the yoke with four radial ventilation ducts. Via investigating on the loss distribution and the heat transfer condition in the rotor, the fluid and temperature fields of half-axial rotors are calculated by using the conjugated heat transfer method. The obtained results are verified by the measured values. The influences of the velocity and temperature of fluid on its effectiveness of cooling excitation windings, and the relationship between the fluid flow velocity and the heat transferred from outer surface of rotor windings are investigated as well. Similarly, the variations of fluid temperature distribution, the flowing velocity, and the heat transfer coefficient distribution in rotors with two or three ventilation ducts are investigated. The effects of the corresponding velocity and temperature of fluid on temperature distribution within both the windward and leeward side excitation windings are also studied.

Discrete fractures are pre-existed in rock masses, which have been proved influencing the mechanical behaviours of rock masses. Modeling the network of discrete fractures is a crucial aspect in studying fluid flow within fractured rock masses. A three-dimensional rough discrete fracture network (RDFN3D) model, developed using the three-dimensional fractal Weierstrass-Mandelbrot relationship and compared with the discrete fracture network (DFN3D) model, was discussed in terms of its influence on both 2D and 3D structural models. The methodology for modeling RDFN3D based on MATLAB code was described. The impact of fracture roughness on seepage characteristics was analyzed and compared for both RDFN3D and DFN3D models. Results indicate that rough structures have a significant effect on the seepage behavior in rock masses. Differences between flow velocities of DFN3D and RDFN3D models increase with increasing pressure gradient and fracture width. Fluid flow velocity in rough structures is lower than that in DFN3D models, which becomes increasingly evident with growing flow pressure and joint aperture.

In order to effectively prevent fire accidents and improve fire management capability, this paper describes the independent designs and builds of an experimental low-cost particle image velocimetry platform for a propane jet combustion flame using traditional mutual correlation theory. The particle image velocimetry (PIV) algorithm is written based on MATLAB software, allowing it to realise image preprocessing, multi-level grid window deformation inter-correlation calculations, and other functions. Fluid flow velocity and vorticity are used as entry points to study the flame combustion mechanism. The air flow field and vorticity above the propane jet flame are analysed. The results show that, from the level of fluid flow velocity, the maximum fluid flow velocity in the test area does not exceed 0.23 m/s, and the maximum transverse fluid flow velocity is close to 0.15 m/s. Additionally, the longitudinal fluid flow velocity is opposite the upper and lower portions of the longitudinal flow velocity, and there is a swirling phenomenon in the propane flame jet. From the vorticity level, the closer to the centre of the jet in the vortex plane, the faster the air flow speed, and simultaneously, in the upper and lower parts of the vortex, the air flow travels in the opposite direction and is of equal size. The particle image velocimetry platform that was independently designed in this study can efficiently characterise the dynamic flow field and the flow characteristics of complex combustion chambers, simultaneously ensuring high efficiency and reducing research costs. It provides a measurement method and experimental basis for the development of fire extinguishing equipment and numerical simulation, while also helping us to carry out a series of subsequent studies on fire extinguishing mechanisms.

To comprehensively understand the influence of the contact area on the flow characteristics of rough single fractures, a rough fracture surface is initially constructed using a spatial frequency domain approach. Subsequently, rough single fractures with varying contact ratios are derived by translating and displacing the fracture surface. The Navier- Stokes equation and Mass-conservation equation are solved by utilizing the laminar flow module integrated within the COMSOL software. The simulation results show that the nonlinear correlation between fluid flow velocity and pressure gradient can be described by using Forchheimer equation. Under the same flow velocity, a higher contact rate will exacerbate the nonlinear characteristics of fluid flow. In contrast to non-contact fractures, the streamlines within contact fractures exhibit increased tortuosity, accompanied by an elongation of flow pathways. Furthermore, with an expanding contact area, the complexity of the streamline pattern amplifies. The overall pressure field distinctly exhibits non-uniform characteristics, with larger pressure gradient observed within localized contact regions, consequently facilitating an increase in flow velocity.

Background: To compare the clinical and functional scores of arthroscopic debridement and repair (conversion to full thickness) surgeries in patients with bursal-side partial-thickness rotator cuff tears (BPTRCT). Materials and Methods: A single-center retrospective study was conducted to compare the arthroscopic debride-ment and arthroscopic repair for BPTRCT performed between March 2017 and September 2021. Arthroscopic debridement patients were grouped as Group 1 and the repair group as Group 2. A total of 98 patients with an average age of 57.5 years (range 29-83 years), including 41 male and 57 female patients, met the inclusion criteria. VAS (Visual Analogue Scale) and UCLA (University of California Los Angeles) shoulder scores applied in the preopera-tive period and in the 12th month of the postoperative clinical follow-ups were evaluated. In addition to the pre-operative and postoperative comparison of both scores, their improvement of these scores was also compared. Results: The mean age of the repair group and the debridement group was 64.4 ±11.02 and 52.6 ±11.24, respective-ly. No significant difference between the two groups was observed in terms of demographic characteristics (p˃0.05). The mean operation time was 91.46 ±16.44 min in the repair group and 49.82 ±13.46 min in the debridement group. The VAS score dramatically improved, from preoperative 5.10±1.23 to postoperative 3.68±1.33 points in the deb-ridement group and from preoperative 5.17±1.35 to postoperative 3.58±1.16 points in the repair group. The two groups had no statistically significant difference in postoperative VAS scores (p=0.991). Preoperative and postopera-tive VAS score improvement was also compared between the groups, however, there was also no statistically signifi-cant difference in terms of VAS score changes (p=0.132). The UCLA scores also dramatically improved, from pre-operative 17.14±4.19 to postoperative 24.57±5.04 points in the debridement group and from preoperative 17.46±5.05 to postoperative 25.48±5.61 points in the repair group. No statistically significant difference was ob-served between the two groups in terms of postoperative UCLA scores (p=0.361). In the postoperative first-year follow-up, no re-tears were observed either in the debridement or in the repair group. Conclusions: Both arthroscopic debridement and arthroscopic repair surgeries provide clinically comparable suc-cessful results and high satisfaction for patients with bursal-side rotator cuff tears. No statistically significant differ-ence was observed between these two methods. Easier early postoperative rehabilitation seems to be the main advantage of the debridement method.

Traumatic triangular fibrocartilage complex (TFCC) injuries require multidisciplinary approach and plan. Trauma to TFCC can lead to instability of the distal radioulnar joint (DRUJ). Injury to TFCC is classified as a stable type that does not cause unstable lesions for DRUJ or unstable type that can cause instability of DRUJ. According to the location and severity of the injury, arthroscopic debridement or arthroscopic repair may be considered. In the ulnar side avulsion of TFCC, which could cause DRUJ instability, arthroscopic examination should be performed to identify an accurate location of the damaged structures, followed by arthroscopic debridement and repair. In the event of TFCC and DRUJ injuries with ulnar positive variance, arthroscopic TFCC repair or ulnar shortening osteotomy after arthroscopic debridement could be considered to solve the instability and ulnar side pain. However, if peripheral TFCC tear with ulnar impaction syndrome and DRUJ instability, it combined operation of ulnar shortening osteotomy and TFCC foveal fixation could be considered. An accurate classification of TFCC and DRUJ injuries is necessary. It is important to resolve and prevent recurrence of ulnar wrist pain caused by instability.

Submarine channel initiation is the process that involved turbulence fluid flow and sculpting submarine channels. The fundamental factor that affects this process is fluid flow velocity and grain-size deposit that the fluid itself carry. This study presents a realistic computational fluid dynamic simulation to simulate the process of submarine channel initiation in a time-dependent equation. This study uses a standard slope model but with the novel approach of adjusted parameters of the actual condition of the submarine channel initiation such as depth hydrostatic pressure, fluid density, and fluid velocity. The result of the simulation showed the correlation between fluid flow velocity and deposited grain-size distribution, which resulting bigger grain size are deposited along with higher fluid flow velocity at the highest activity of 14 m/s and smaller grain size are deposited at lower fluid flow velocity at the lowest activity of 0 m/s among the geometry of the submarine fan.

Dynamic behaviour of fluid-transporting axially functionally graded non-uniform Rayleigh pipes lying on variable two-parameter elastic foundation

The purposes of this research are to find out how the simulation of flow velocity, mass flow rate and pressure that occur in each variation of Reynold numbers on the triangle pipe arrangement of solid work software. By using test and simulation analysis methods, using a number of tools and materials so that they can be simulated and simultaneously analyze the resulting design. The tools and materials used in the simulation and analysis process in this design are (1) computers with specifications of the Intel (R) Xeon (R) CPU E3-1246 v3 @ 3.50Ghz 3.50 GHz (2) a solid work keel device for analyzing pressure. This fluid mass flow rate is influenced by the velocity of fluid flow and the temperature at this fluid can influence fluid density and specific gravity. This fluid speed can affect the pressure that hits the pipe. In the simulation results, there is a significant pressure change due to the speed that changes over the sidelines of the same pipeline. This change raises the loss of friction in the arrangement of the pipe pipeline due to the pressure factor that hit the pipe. The pressure that occurs is influenced by the velocity of fluid flow, fluid mass flow rate and cross-sectional area on the triangle pipe arrangement.