The paper involves results of numerical modeling in ANSYS of the behavior of gas flows emanating from composite nozzles (consisting of two concentrically placed hollow cylinders with different shares of the peripheral annular part; the same gas (oxygen) is supplied through the inner and outer parts). The study was conducted for different designs of composite nozzles: with 25%, 50%, and 75% peripheral fractions of the nozzle with the same outer nozzle diameter and equal total cross-sectional area. The results were compared with the results of numerical modeling of blowing through a cylindrical nozzle and a Laval nozzle with similar equivalent nozzle diameters. It was found that the peripheral part of the composite-type flow is more responsible for the characteristics of the gas jet formed and its axial velocity parameters. Accordingly, at a peripheral fraction of 25%, a flow is formed with characteristics close to the flow that is formed by a Laval nozzle. When the peripheral fraction is increased to 50% and 75%, a more complex multi-node structure of interacting flows is formed. It is reflected and confirmed by the shadow imaging method and by interaction with a liquid bath using the air–water model.

Adaptive time-stepping strategies for efficient simulation of internal combustion flows and coupled heat processes in hollow cylinders

Due to the increasing importance of engineering plastics in diverse engineering fields, demand for these materials has grown alongside technological progress, driving the development of tailored properties for specific applications. This study evaluates the wear behavior of three polymer groups manufactured using additive manufacturing (Material Extrusion, MEX): polylactic acid and carbon fiber-reinforced polylactic acid, both fabricated by the deposition technique and reinforcement with epoxy resin. High-precision three-dimensional models were fabricated for each composite polymer to improve accuracy and performance. Samples were prepared as hollow cylinders with deposition thicknesses defined by diameter reduction ratios (wt.%) of 10%, 20%, and 40%, aiming to investigate the effect of epoxy reinforcement on wear behavior.Both wt.% and applied load during testing were considered as key factors influencing composite performance. Wear properties were assessed using a pin-on-disc device, following a systematic approach to examine the relationship between these parameters and the tribological behavior of the materials. Data analysis was conducted with MINITAB 19, employing the Taguchi method for experimental design and evaluation. Results demonstrated that the adopted design methodology enhanced adhesive wear resistance in all composites. Furthermore, the wt.% had a greater influence on wear performance than the applied load within the scope of this study.

To determine the influence of soil-structure interface behavior on the bearing capacity and deformations of geotechnical structures, suitable testing methods capable of simulating in situ conditions are required. This article introduces a novel test method for soil-structure interface tests. A hollow cylinder triaxial device is modified to conduct interface tests with four independent control variables. This enables investigations of the influence of different anisotropic stress states on the contact shear behavior of granular material. First test results on Karlsruhe fine sand are presented with a variation of the lateral normal stresses acting on the plane orthogonal to the shear (i.e., contact) plane. These tests are conducted in two modes: in mode A long samples (do = h) are used whereas in mode B short samples (2(do − di ) = 1/ h) are used. The results of the test series in mode A show that the failure occurs either in the soil (on the plane with the highest ratio of the shear and normal component of the stress vector τ /σ N) or on the contact plane (where the shear strength is reduced). The failure in the test series with mode B is restricted to the horizontal plane due to sample geometry. The findings will be utilized in the future to test and develop various modeling methods for soil-structure interfaces.

The direct simple shear (DSS) test carried out under constant volume (CV) conditions forms one of the primary laboratory techniques to characterise soils and tailings. The use of CV conditions to simulate undrained shearing is supported by historical evidence on the testing of a saturated clay and sands, with this evidence being incorporated into current guidelines and state of practice procedures. However, some recent comparisons of the results of undrained hollow cylinder simple shear (HCSS) and CV DSS tests on predominately silt gold tailings adopting state of practice test procedures (i.e. inundation of the sample after loose moist tamping) showed much less post-peak strength loss in the gold tailings than the undrained HCSS tests. The current study investigated this discrepancy further by carrying out DSS tests under high back pressures, undrained simple shear tests with flexible membrane and constant cell pressure and DSS tests after flushing with carbon dioxide and with use of a small back pressure. In all cases, the undrained tests or DSS tests with greater effort put towards saturation exhibited greater post-peak strength loss more consistent with the HCSS and the critical state line. The importance of these results on the estimation of tailings brittleness in engineering practice was outlined.

Torsional fracture of solid and hollow cylinders

Random Field for Modeling Uncertainties in Hollow Cylinders: Applications to Fluctuations in Drilling Boreholes

Effects of apertures on the multiphase flow characteristics of vertical water entry of hollow cylinders

Transient axially symmetric guided wave propagating in nematic liquid crystal elastomer hollow cylinders

This study investigated the hydrodynamic performance of a system consisting of a rigid, bottom-mounted, surface-piercing cylinder coaxially surrounded by a partially immersed coaxial compound cylindrical breakwater to optimize its configuration to improve the response to capillary–gravity waves. The compound breakwater consists of two impermeable, thick-walled cylinders of the same radius placed vertically in the water column and connected by an intermediate porous hollow cylinder of the same radius. The analysis is done using linear wave theory. Velocity potentials in each fluid region are derived using the eigenfunction expansion method, and unknown coefficients are obtained by applying appropriate matching conditions at the interfaces. Hydrodynamic quantities such as wave forces, free surface elevations, added mass, and damping coefficients for surge and pitch motions are evaluated. It is observed that the draft of the porous hollow cylinder and thick cylinder of the compound breakwater, along with the porous parameter, has a significant influence on all evaluated hydrodynamic parameters.

ABSTRACT In order to investigate the dynamic shear characteristics of rubber sand under cyclic loading, a series of cyclic torsional shear tests was conducted using a hollow cylinder torsional shear apparatus. The effects of four cyclic vertical stress ratios (CVSRs = 0.15, 0.25, 0.35, and 0.45) and four cyclic torsional stress ratios ( η = 0, 1/6, 1/3, and 1/2) on the strength and volumetric deformation characteristics of rubber sand were analyzed. Based on the tests, a three‐dimensional undrained discrete element model of a hollow cylinder torsional shear test was developed to further examine the evolution of particle motion, porosity, coordination number, and fabric anisotropy during the shearing process. The results show that with increasing cyclic vertical and torsional stress ratios, horizontal reconstruction of shear bands becomes more pronounced, and axial strain accumulates more rapidly. When CVSR and η are relatively small, the shear modulus decreases gradually with their increase, and the damping ratio remains relatively stable. At the mesoscopic level, the contact network exhibits a decrease in coordination number, a rapid increase in porosity, and an accelerated decay of normal contact force. When CVSR and η are relatively large, the particle skeleton undergoes rapid liquefaction and reorganization, with the shear modulus and damping ratio decreasing sharply. At this stage, the number of normal contacts is reduced to a minimum, and the normal contact force almost completely disappears.

Abstract Thermoelastic stresses in a single-phase, finite-width slab or hollow cylinder with a constant-velocity growing or receding boundary were derived under time dependent arbitrary thermal load. The analysis began by solving the conduction equation for a homogeneous, single-phase, finite-width slab subjected to a unit step temperature change with a growing or receding boundary in the Laplace domain. A series approximation was then employed for the inverse transformation to the time domain. The slab solution was extended to a cylindrical geometry via conformal mapping, with convection allowed at the fixed boundaries (the opposite face of the slab or the outer radius of the cylinder). Generalization to arbitrary temperature histories was accomplished using Duhamel's principle and Laplace convolution theorem. Integral elasticity equations were used to relate the transient temperature fields to the resulting thermoelastic stresses. Comparisons with finite element simulations showed excellent agreement, particularly for low to moderate growth/recession velocities. Due to the changing thickness, neither thermal nor stress fields attain steady state conditions, especially when the growth or recession is higher. In such instances, the thermal- and stress-states tend to become linear with time, reflecting the constant velocity of growth/recession. The developed solutions are applicable to determine thermal stresses during machining, wear, erosion, corrosion, and/or additive manufacturing, especially for lower temperature solid-state methods such as cold-spray.

Abstract In certain shale formations, time-dependent deformation causes the annulus between the borehole and casing to close naturally, offering the potential for a self-sealing barrier without annulus cement in petroleum well. In this study, the mechanical behavior of Pierre II shale is investigated as a candidate material for such shale barriers. Laboratory tests are combined with numerical modeling to evaluate the long-term performance of the annular seal. A downscaled shale barrier experiment is conducted at drained condition using a hollow cylinder shale specimen and a central casing, subjected to externally applied isotropic stress under controlled pore pressure. Strain gauges attached to the casing allowed continuous monitoring of stress evolution after contact of the borehole with the casing. To characterize the time-dependent behavior of the shale, stress relaxation tests are performed on companion specimens at zero volumetric strain. A constitutive model incorporating both viscoelastic (Burgers-type) and viscoplastic (Bingham-type) components is implemented in a finite difference simulation, which can be calibrated using laboratory data. The simulation for the shale barrier experiment with the calibrated parameters captures the main trend of the casing stress evolution. Due to the axisymmetric assumption of the model, the non-uniform stress response measured in the experiment cannot be explained. Nevertheless, the simulation provides insights into the continuing reduction in annulus permeability driven by increasing mean stress over a long period after casing contact. The study demonstrates a viable workflow for predicting the mechanical response of the shale barrier and supports the use of casing stress measurements to track barrier development. The integrated experimental-modeling approach is promising for assessing the feasibility of natural shale barriers in field applications.

Novel gradient-dependent approximation framework for wave propagation analysis in ZnO-GaN functionally graded piezoelectric hollow cylinders

Abstract This study explores a simple, low-cost experimental method for determining the rotational inertia constant ( β ) using the rolling motion of everyday objects on an inclined plane. Four objects with distinct geometries—a bouncy ball, battery, ping pong ball, and cardboard core—were analysed by measuring their rolling times over a 0.4 m incline set at a 7.7° angle. The experimental values (β ex) were calculated and compared to their respective theoretical values ( β th ) derived from classical mechanics. The battery (β ex = 0.48) and ping pong ball (β ex = 0.64) closely matched their theoretical predictions (0.5 and 0.67), while the bouncy ball exhibited a large discrepancy (β ex = 0.32) due to energy losses from bouncing. The cardboard core was modelled in two ways: as a thin-walled hollow cylinder ( β th = 1 ) and a thick-walled cylinder ( β th = 0.91 ). The latter provided a better fit to the experimental data, reducing the error from 10.05% to 1.15%, highlighting the importance of realistic modelling. Additionally, a graphical method—plotting t 2 versus 1 sin θ —was applied to the battery and yielded β = 0.515 , in excellent agreement with theory. These results illustrate the potential educational value of combining hands-on experiments with model evaluation and data analysis, offering a practical approach to enhance students’ understanding of rotational dynamics and the limitations of idealised physical models. The experiment is highly replicable in classroom settings, requires only household objects and basic tools, and supports inquiry-based physics learning in resource-limited environments.

Abstract Optical differentiation is crucial for high-speed image processing, but most optical analog spatial differentiators based on metasurfaces are currently limited to a single type of low-order differentiation operation. We present a dielectric metasurface composed of silicon hollow cylinders that leverages electric quadrupole (EQD) and magnetic dipole (MD) resonances to achieve wavelength-tunable 2D multi-order differentiation. Specifically, at 1340 nm (MD-dominant), 1140 nm (hybrid EQD-MD), and 1010 nm (EQD-dominant), the metasurface performs second-, fourth-, and sixth-order differentiation, respectively. The device features a 430-nm bandwidth, a maximum numerical aperture of 0.71, and a maximum transmittance of 96%, enabling high-quality edge extraction for complex images. We believe this to be the first integration of wavelength-division multiplexing and multi-order differentiation in a single-layer metasurface, advancing compact and multifunctional optical computing for applications such as autonomous driving and medical imaging.

A two-way fluid–structure interaction method is used to investigate the cavity evolution, trajectory, and motion characteristics of a hollow cylinder during oblique high-speed water entry. The finite volume method is used to handle the fluid domain, and the finite element method is used to handle the structural domain. Meanwhile, key data from the two computational domains are exchanged during each iteration process to achieve fluid–structure coupling simulation. The results indicate that a jet forms in the middle of the hollow cylinder, which will deflect and eventually collide toward the upstream side of the cavity. Due to the obstruction of the internal jet, the water entry angle of the hollow cylinder changes less than that of a completely sealed hollow cylinder. Compared to the completely sealed hollow cylinder, the completely open hollow cylinder has significantly smaller deformation and strain energy during water entry, resulting in better stability and durability. As the initial velocity increases, the displacement, fluid force, and stress of the completely open hollow cylinder all increase. As the initial water entry angle increases, the stress and strain energy at a specific angle (45°) are smaller than those of a completely sealed hollow cylinder. As the diameter increases, the stress and strain energy experienced by the completely open hollow cylinder gradually increase. As the thickness increases, the force and stress acting on the completely open hollow cylinder increase. As the length increases, the trajectory of the hollow cylinder becomes closer to a straight line.

Turbines are crucial to our energy infrastructure, and ensuring their bearings function with minimal friction while often supporting heavy loads is vital. Vibrations within a bearing can signal the presence of defects, friction or misalignment. However, current detection methods are neither robust nor easy to automate. We propose a more quantitative approach by modelling the elastic waves within bearing raceways. By approximating the raceway as a hollow cylinder, we derive straightforward 4 × 4 systems for its vibrational modes, enabling both forward and inverse problem solving. We also demonstrate how to significantly reduce the number of required sensors by using a simple prior: the known number of rollers and their angular speed. We present numerical examples showcasing the full recovery of contact traction between bearings and the raceway, as well as the detection of elastic emissions.

In seismic signal analysis, separating the P- and S-wave components is a crucial yet challenging task. Different from methods that rely on signal postprocessing, a sensor is developed to directly output the P- and S-wave components of seismic waves by using the inherent symmetry of stress waves. For a hollow piezoelectric circle, P waves generate equivalent electrical potentials in two semicircles, whereas S waves induce opposite potentials in adjacent quadrants. Thus, a sensor designed using a hollow piezoelectric cylinder with four electrodes enables P- and S-wave separation through simple algebraic operations on the output signals. The validity of this concept is first confirmed through finite-element simulation. Then, compression and shear fatigue tests are conducted to test its realistic performance. The numerical and test results indicate that P- and S-wave signal outputs do not interfere with each other and that the sensor accurately reflects the ratio of P to S waves in the case of a composite body wave. In summary, the developed sensor allows simplification of signal processing for separating the P- and S-wave components of a composite wave through sensor structural design by using the intrinsic symmetry of body waves.

Investigation of the Effect of Particle Morphology on the Noncoaxial Behavior of Sands Using a Hollow Cylinder Shear Apparatus