Home – Home – Jornals – Journal of Applied Mechanics and Technical Physics 2025 number 6

This paper investigates a line-drive waterflood pattern with two injection wells, between which a hydraulic fracture spontaneously propagates. Using a simplified model implemented in the RN-KIM hydrodynamic simulator, we consider a scenario where propped fractures from the two injectors connect to form a single dominant spontaneous hydraulic fracture. We model the propagation of a spontaneous fracture between two wells with existing propped fractures and analyze how the difference in wellhead injection pressures affects the injection rate in each well. The results demonstrate that an injection pressure difference between adjacent wells can cause a severalfold decrease in the injection rate or even a complete well shut-in. This occurs when the well with the higher bottomhole pressure “dominates” the flow within the high-conductivity fracture. Furthermore, we analyze the impact of the operating conditions of adjacent injectors and the geomechanical properties of the reservoir on the injection rate.

We analyze unsteady characteristics of the flow resulting from the interaction between a longitudinal vortex-generated by jet injection from a wall-and a turbulent boundary layer. Velocity fields are measured using particle image velocimetry. Our data analysis includes the assessment of turbulence anisotropy and characteristic length scales of turbulent structures, as well as proper orthogonal decomposition. The results reveal mutual interaction between the turbulent boundary layer and the longitudinal vortex, which depends on the vortex intensity. It is demonstrated that the jet vortex generator significantly alters not only the mean flow but also the unsteady characteristics of the turbulent boundary layer.

This paper presents a numerical investigation of the stress-strain state in a non-spherical shell subjected to pulsed loading. We examine the influence of the height-to-radius ratio of elliptical heads on the maximum stress values within explosion chamber shells. The dependence of the stress-strain state at the shell pole on the head height is also analyzed. It is demonstrated that employing elliptical heads with an optimal height-to-radius ratio mitigates stress concentration.

We derive a particular solution for a macroscopic model of a two-velocity, two-temperature mixture of gas and suspended particles. The solution to the system of partial differential equations takes the form of a monochromatic sound wave. The mixture is modeled within the interpenetrating continuum approach, incorporating relaxation terms that account for momentum and thermal energy exchange between the carrier and dispersed phases. The particular solution is constructed via the Fourier method and can serve as a verification test for numerical models of gas-particle flows. For arbitrary velocity and thermal relaxation times, the solution is obtained by numerically calculating the complex roots of a sixth-degree polynomial dispersion relation. In the case of infinitely small relaxation times (a state of relaxation equilibrium pertinent to modeling ultra-dispersed mixtures), the reference solution reduces to a traveling wave propagating at the effective speed of sound in the gas-dust medium. We demonstrate the sensitivity of this effective sound speed to the parameters governing the heat transfer processes. The code used to generate the particular solution for arbitrary input parameters is publicly available.

We investigate the electrophoresis of a dielectric particle possessing a hydrophobic surface and high surface conductivity through a combination of numerical simulations and analytical methods. Our results show that, under a moderate electric field and high surface charge density, the particle velocity increases, with the contribution from surface conductivity significantly exceeding that of the slip length. An analytical expression for the electrophoretic mobility of a hydrophobic particle is derived. This formula consists of three terms: (1) the linear term from the classical Helmholtz-Smoluchowski relation; (2) a term accounting for the hydrophobic surface effect; (3) a term representing the contribution of surface conductivity induced by the high surface charge density. Results are presented for both small and large slip lengths, corresponding to micro- and nanoparticles, respectively. A comparison between the numerical and analytical solutions demonstrates excellent agreement between the two approaches.

We present an experimental investigation of the transport of water-dissolved rhodamine B fluorescent dye within a porous medium subjected to oscillatory flow. The porous medium consists of a rectangular cell packed with cylinders oriented perpendicular to the cell plane. The applied measurement technique enables simultaneous determination of the rhodamine B mass transfer rate and acquisition of both the instantaneous and time-averaged secondary flow velocity fields in the inter-cylinder space. The results demonstrate that the effective diffusion coefficient attributable to secondary flow scales linearly with the Peclet number, which is defined using the characteristic velocity of the secondary flow. At low dimensionless oscillation frequencies, a universal relationship is observed between the effective diffusion coefficient and the Peclet number. At moderate dimensionless oscillation frequencies, however, the proportionality constant between these parameters increases with rising oscillation frequency.

We investigate the effects of the Reynolds number, static pressure, and flow temperature on the evolution of vortex structures in the turbulent wake of a circular Teflon cylinder. Velocity fields are measured using particle image velocimetry (PIV) in a hydrodynamic facility for Reynolds numbers in a range of 1.75 · 105 ÷ 2.84 · 105. The hydraulic drag coefficient of the cylinder, together with time-averaged wake characteristics, indicates an earlier onset of the drag crisis, similar to that observed for rough, non-hydrophobic surfaces. It is shown that a reduction in the freestream pressure leads to both an increase in the wake size and the hydraulic drag. Furthermore, an increase in the flow temperature leads to a decrease of the hydraulic drag of the cylinder, despite larger wake dimensions. This reduction is attributed to a possible decrease in Reynolds stresses on the cylinder surface and the associated frictional drag component.

We experimentally investigate the perforation of wire mesh screens by an aluminum projectile over a range of impact angles. The study focuses on the fragmentation mechanism driven by the penetration of mesh wires into the projectile material. A series of hypervelocity impact tests on thin mesh screens reveal the following: as shockwave-induced fragmentation diminishes and the impact angle increases, the projectile undergoes fragmentation primarily via the wire penetration mechanism. We assess the performance of a mesh screen as a protective layer at various impact angles, comparing its effectiveness to that of a solid bumper shield. Additionally, the ballistic characteristics of the resulting fragment cloud are determined.

We experimentally investigate the distributed receptivity of a laminar swept-wing boundary layer to unsteady freestream vortices with streamwise-aligned vorticity in the presence of spanwise-uniform surface waviness. Experiments were performed on a 25° swept-wing model in a well-controlled disturbance environment. We demonstrate that unsteady longitudinal vortices can very efficiently excite-in a distributed manner along the streamwise direction-unsteady crossflow instability modes at specific combination transverse wavenumbers. This excitation results from the scattering of the vortices by the surface inhomogeneities. The present paper (Part 1 of this study) is devoted to describing the experimental approach and its theoretical background, the mean flow structure, the experimental evidence of the high efficiency of this receptivity mechanism, and the experimental verification and critical role of the streamwise wavenumber resonance. Part 2 of this investigation focuses on the experimental determination of the amplitude and phase of the distributed vortex-roughness receptivity coefficients as functions of disturbance frequency and transverse wavenumber. In Part 2, we also determine the receptivity coefficients responsible for exciting crossflow instability waves on a smooth surface and present a comparative assessment of the relative efficiencies of these two distinct mechanisms.

We present a numerical study of the transmission of a shock-wave pulse from a gas into a porous medium saturated with a bubbly liquid. The process is modeled for one-dimensional planar motion under the assumption of a viscoelastic porous skeleton. We examine the dynamics of a shock pulse propagating within a porous medium saturated with a gas-liquid mixture, considering the cases where the skeletal matrix consists of either sandstone or unconsolidated sand. The analysis focuses on the influence of both the shock pulse parameters and the properties of the gas-liquid mixture on the wave dynamics.

We investigate the generation of disturbances in a supersonic wind-tunnel flow by a two-dimensional surface roughness element located on the test section wall. The study focuses on the case where the roughness height is small relative to the thickness of the on-wall turbulent boundary layer. The investigation combines numerical simulations, which resolve the turbulent boundary layer, and experimental measurements using hot-wire anemometry. We examine the effects of the roughness height and width, as well as the flow Mach number, on the generated flow disturbances. The results show that the presence of the two-dimensional roughness induces a stationary N-wave disturbance in the freestream, accompanied by a region of elevated unsteady fluctuations across a broad spectrum. An increase in roughness height is shown to amplify the disturbance amplitude and enlarge its spatial scale. For small roughness widths, the freestream disturbance maintains an N-wave profile. As the width increases, the disturbance amplitude remains constant, but the N-wave bifurcates into two distinct shock waves. Finally, we compare the spatial scales of the mean-flow disturbance for a fixed roughness geometry at Mach numbers of 2.0 and 2.5.

We present a numerical study of a submerged round jet at a low Reynolds number, subjected to harmonic disturbances from two sources positioned at opposite lateral boundaries near the inlet section. Our results demonstrate that, for a specific combination of control parameters, the flow undergoes bifurcation, splitting into two distinct branches-a phenomenon also observed in various other experimental and computational studies involving different types of acoustic and mechanical disturbances. The time-averaged flow velocity fields are computed. The effect of the disturbance amplitude on the jet behavior is investigated, and a critical amplitude threshold, above which flow splitting occurs, is identified.

We present the results of an experimental investigation into heat transfer within the flow duct of a supersonic wind tunnel during tests with solid-fuel combustion products containing a minor fraction of condensed particles. Static pressure and heat flux density distributions along the duct are measured using an array of 29 heat flux sensors and 25 pressure transducers. The design of the heat flux sensors and the key aspects of their implementation are described. Suitable scaling parameters for non-dimensionalizing the experimental data are proposed. Based on the processed and compiled heat flux and pressure distributions, a conceptual model is developed to describe the flow processes inside the supersonic diffuser channel. The primary factors governing the thermal loads on the diffuser structure are identified.

We develop a continuum-based physical and mathematical model to investigate coating growth in the cold gas dynamic spray (cold spray) process. The model accounts for collisions between feedstock powder particles and the substrate (or deposited coating) surface across a range of impact angles. Simulations of coating deposition onto a substrate with a wavy surface topography, using a nozzle translating at a constant velocity, reveal distinct deposition conditions on the descending and ascending slopes of the substrate. Further simulations incorporating forward and backward nozzle tilt angles relative to the translation direction identify an optimal impact angle that maximizes the resulting coating thickness, corresponding to peak deposition efficiency.

We investigate the process of conveying bulk materials within the channel of a dual-mass tubular vibratory elevator, operating in an inclined (elevating) configuration. Using construction sand as the test medium, we analyze the influence of the oscillation frequency and amplitude of the conveying elements, the channel wall inclination angle, and the bulk fill density on both the maximum achievable lift height and the material transport velocity. Our findings indicate that the operating frequency should be carefully detuned from the resonant frequency of the system to ensure stable performance. The most effective control parameters are identified as the oscillation amplitude of the conveying elements and the inclination angle of the elevator relative to the horizontal. Finally, we propose recommendations for refining the process model and suggest directions for future research.

We present an experimental study of internal wave focusing generated by the horizontal oscillations of a toroidal body in a linearly stratified fluid. The cross section of the body is circular, while the curve connecting the centers of these cross sections is elliptical, defining a torus-like shape. For the case of an axisymmetric oscillating torus, the measured amplitude distribution of internal waves in its vicinity is compared with predictions from linear theory under the thin-body approximation. We show that wave generation by non-axisymmetric radiators leads to a reduction in the wave amplitude within the focal zone, attributable to differences in both the total radiated power and the spatial structure of the focusing region. Finally, we construct isosurfaces of the experimentally measured wave amplitudes in the focusing zone and compare these data with results derived from ray theory.