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The influence of an electric discharge in a supersonic gas flow modeled by a heat source with a specified intensity and configuration on the development of a turbulent boundary layer ahead of a flat step is numerically studied. If the discharge power is sufficiently large, it is demonstrated that heat transfer to the wall does not affect the position of separation, which arises due to a non-zero shear stress on the body surface and is caused by the development of a reverse flow in the core of the boundary layer.

In this work, an exact analysis on the effects of heat generation and nanoparticle volume concentration on an unsteady free convective flow of a nanofluid past an impulsively started infinite vertical plate is presented. Nanofluids containing nanoparticles of aluminum oxide, copper, titanium oxide, and silver with a nanoparticle volume concentration range smaller than or equal to 0.04 are considered. The governing dimensionless partial differential equations are solved by using the Laplace transform technique. The effects of heat generation and nanoparticle volume concentration on the velocity and temperature profiles are represented graphically. The expressions for the skin friction coefficient and Nusselt number are derived. The effect of heat transfer is found to be more pronounced in a silver-water nanofluid than in the other nanofluids. Comparisons with other published results are found to be in excellent agreement.

This study presents a numerical investigation and prediction of the flow field in three-dimensional submerged hydraulic jumps. The volume of fluid (VOF) method is used to simulate the free surface. The turbulent structure is simulated by using different turbulence models, such as the standard κ-ε model, RNG κ-ε model, realizable κ-ε model, and Reynolds-stress model (RSM) closure schemes. The capabilities of the turbulence models are investigated with the standard wall functions and enhanced wall treatment methods. A comparison between the numerical and experimental results shows that the numerical model is adequate for predicting the flow pattern and free surface of submerged hydraulic jumps. The RNG κ-ε turbulence model with the enhanced wall treatment method ensures the highest accuracy in the water surface simulation. Near the channel bed of a fully developed region, the RSM model with the enhanced wall treatment method shows better agreement with the experimental longitudinal velocity than the other turbulence models. The standard κ-ε model predicts the longitudinal velocity more accurately than the RNG and realizable κ-ε models.

Reactive solute transfer in a boundary-layer stagnation-point flow over a shrinking sheet with a uniform diffusive mass flux is investigated. The first-order chemical reaction is considered. By similarity transformations, the governing partial differential equations are converted into self-similar nonlinear ordinary differential equations. Then the transformed equations are solved numerically by using the shooting method. Dual solutions for the solute distribution are found. The study shows that the concentration at the point increases with increasing velocity ratio parameter for the first solution and decreases for the second solution. Due to an increase in the Schmidt number and reaction rate parameter, the concentration and concentration boundary layer thickness decrease in the presence of the mass flux.

The aim of this research is to investigate the heat transfer characteristics of a top heat mode closed-looped oscillating heat pipe with check valves (THMCLOHP/CV). Ethanol is used as a working fluid with filling ratios of 30, 50, and 80% of the total volume of the tube. The THMCLOHP/CV is made of a copper tube with an inside diameter of 2.03 mm. The angle of inclination is 90 ^oC from the horizontal axis with 40 turns, two check valves, and an evaporator length of 50, 100, and 150 mm. The operating temperatures are 44 and 55 ^oC. It is found that the thermal resistance decreases significantly as the working temperature is increased. Thus, the evaporator length affects the thermal resistance of the THMCLOHP/CV. The presence of the THMCLOHP/CV is clearly demonstrated to contribute to thermal performance improvement.

This paper presents the results of experimental studies of acoustic emission occurring in rock-salt samples due to their local and volumetric heating under static mechanical loading preceding heating or occurring simultaneously with it. Thermoacoustic emission (TAE) parameters in rock salt depending on its structural heterogeneity were determined. Patterns of change in the TAE activity in test samples of the geomaterial under volumetric heating and subsequent cooling for different values of mechanical preloading were established. The established patterns can be used to predict the fracture of solid rock salt from results of measurement of s TAE in an extracted core.

The present paper addresses application of the general shear deformation theory for the thermoelastic analysis of a functionally graded cylindrical shell subjected to inner and outer loads. The shear deformation theory and the energy method are employed for this purpose. This method presents the final relations by using a set of second-order differential equations in terms of the integral of material properties over the shell thickness. The obtained formulation can be solved for two well-known functionalities.

This work is focused on an experimental study of E26-2 pipeline steel tearing by mode III. The crack propagation length is obtained as a function of the applied force magnitude for specimens of different thicknesses and widths. The critical stress intensity factor and the essential work needed for crack propagation are determined by the energy balance method. It is demonstrated that these variables depend on the pipeline thickness and specimen geometry.

The problem of the stress state of a piecewise-homogeneous elastic body with a semi-infinite crack at an interface, in which near the vertex inserted a thin rigid pointed inclusion of finite length. The crack faces are loaded by predetermined stresses, and at infinity, the body is stretched by predetermined normal stresses acting along the crack. The inclusion is acted upon by external forces that have predetermined main vector and moment. The problem reduces to the matrix Riemann boundary-value problem with a piecewise constant coefficient. The solution of this problem is constructed in explicit form using the Gauss hypergeometric function. The angle of rotation of the inclusion, complex potentials, and stress intensity factors near the ends of the inclusion are obtained.

Plastic structure formation in AD1 aluminum has been studied experimentally and theoretically using a physical phenomenological model of cyclic and nearly cyclic plastic deformation with large strain intensities accumulated in one and several cycles. Based on the results obtained, the proposed model of the process was verified, the concept of severe plastic deformation was refined, its role in structure formation was investigated, and the existence of a limit of grain refinement during deformation processing of metals was shown.