This study investigates the flow and heat transfer characteristics of copper (Cu) and silver (Ag) nanofluids over a permeable, moving flat plate embedded in a porous medium under the influence of a uniform magnetic field. Key effects such as thermal radiation, viscous dissipation, nanoparticle volume fraction, and suction/injection are incorporated into the model. The governing partial differential equations are reduced to ordinary differential equations using similarity transformations and solved numerically via the Runge-Kutta fourth-order method with a shooting technique. Results reveal that Ag-water nanofluid exhibits a higher temperature profile, whereas Cu-water shows greater skin friction and heat transfer rates. Velocity decreases with increasing magnetic field strength, porosity, volume fraction, and suction/injection parameters. Thermal boundary layer thickness increases with magnetic and porosity parameters but decreases with stronger suction. The Nusselt number increases with nanoparticle concentration, and temperature rises with higher viscous dissipation but decreases with thermal radiation.

The modern battlefield requires highly accurate missiles, which has led to the modification of unguided missiles into guided versions. This paper presents the process of adapting an unguided missile with a range of 40 km into a guided version using a canard control system. A key aspect of the upgrade was the development of a control system that allows the trajectory to be corrected after crossing the apex of the flight path, particularly during the descent phase. This paper discusses the design details and application of a two-channel control system (pitch and yaw) in which the control signals are synchronized with the speed of the projectile. Mathematical modelling and numerical simulations have shown that, with appropriate control parameters, a zero mean control force can be achieved, leading to trajectory stabilization and minimized aiming errors. The proposed solution provides a basis for further research and dynamic field tests and can contribute to the development of precision guidance technology for surface-to-surface missiles.

The paper describes the model of an oscillator with damping, whose vibrations are forced by a random series of impulses. The mathematical model of the inverse problem used to calculate the distributions can only be applied when the values of the random impulses are known. If impulse values cannot be estimated based on the vibration signal, machine learning algorithms and feature engineering should be used to determine their distribution. In the discussed paper, unsupervised machine learning (specifically, the agglomerative hierarchical clustering) is employed to evaluate the applicability of the algorithms to the problem of recognizing the magnitudes of random impulses and characterizing their distributions.

This paper presents a numerical investigation of unsteady, two-dimensional magnetohydrodynamic (MHD) mixed convection flow and heat transfer over a permeable stretching cylinder embedded in a porous medium. The governing conservation equations of mass, momentum, and energy are formulated by incorporating the effects of viscous dissipation, temperature-dependent thermal conductivity, Joule heating, thermal radiation, and a uniform transverse magnetic field (with negligible induced effects). Additionally, slip velocity and variable surface heat flux are also considered to enhance the model’s applicability to engineering systems. Through appropriate similarity transformations, the governing partial differential equations are reduced to a set of nonlinear ordinary differential equations, which are solved using MATLAB’s bvp4c scheme. The influence of key dimensionless parameters on velocity and temperature distributions, skin friction coefficient, and Nusselt number is thoroughly examined. Comparative analysis between the stretching cylinder and the flat sheet configurations reveals that the cylinder’s curvature significantly thickens the momentum and thermal boundary layers, while enhancing the surface shear stress and heat transfer rate. These findings offer useful implications for the design of thermal systems involving curved geometries, such as cylindrical heat exchangers and pipes.

The paper presents a new fully parametric geometrical model of a ventricular assist device (VAD) together with an example of a comprehensive automated workflow integrating multidisciplinary tools for geometrical design, fluid dynamic assessment, and automated shape optimisation. Advanced geometrical constructions are applied to develop a new fully parametric CAD (Computer Aided Design) model that generates a stable, watertight geometry of an axial blood pump in both non-uniform B-spline representation and node-to-node triangular mesh. The presented example of a fully integrated simulation workflow that combines open-source software tools within a user-friendly environment, demonstrates its efficiency while benefiting from the fully parametric, easily adjustable VAD model. The proposed geometrical modelling and numerical simulation approach offers a seamless, ready-to-use test case for computer aided design, analysis and optimisation of VADs. The shown results demonstrate the essential advantages of the parametric modelling approach, showcasing its potential application in performance improvements of an axial blood pump through shape optimisation. Overall, the paper highlights the viability of automated, multidisciplinary design workflows in biomedical engineering.

One of the methods of analyzing a heat exchanger consists in determining the heat transfer rates and outlet temperatures of the fluids for known mass flows, inlet temperatures, and exchanger type and size. This requires calculating the exchanger performance for known transfer surface area but unknown outlet temperatures. The concept of the heat transfer effectiveness (HTE) can be applied to determine the heat transfer rate of the specified heat exchanger without knowing the outlet temperatures of the fluids. This article presents the results of calculations of the HTE parameter for a cross-flow heat exchanger with staggered tube banks. The analysis takes into account six different models of convection heat transfer over the tube banks. In this scenario, the impact of the applied convection model on the value of HTE for the considered heat exchanger was examined. For the considered calculation cases, the value of the HTE parameter is in the range from 0.3 to 0.48 and it decreases with the increase of the flow rate of both air and the flue gases. It has been shown that the results of all four models are very similar, while the other two models bring about either an increase or a decrease of the values of the parameter investigated. It was found that for the analyzed heat exchanger a simplified criterion for the convection heat transfer over tube banks can be used to determine the effectiveness of the heat transfer with the Reynolds number being the only parameter.

This study presents an analytical model of a clamped circular sandwich plate with a functionally graded core, developed within the framework of an individual nonlinear shear deformation theory. The mathematical formulation is an original contribution, providing a unified representation of various structural configurations -- including three-layer-like, five-layer-like, homogeneous single-layer, and intermediate forms -- through a single continuous function. The variation of Young's modulus across the core is controlled by three parameters, enabling flexible modeling of material gradation. The governing equations are derived using Hamilton's principle and are solved analytically through an approximate solution method. The proposed model allows investigation of the effects of material property variation and the core-to-plate thickness ratio on the fundamental natural frequency, as well as on the shear effect coefficient and plate mass, yielding general conclusions supported by a coherent theoretical framework.

This research examines the aerodynamic performance of wavy (corrugated) airfoils, focusing on the effects of two angles of attack: the airfoil’s and the tail’s (β). Simulations used the W1011 airfoil at a Reynolds number of 200 000, with airfoil angles of 0o, 2o, 5o, and 8o, and tail angles of 0o, 10o, 20o, 30o, and 40o. Results were validated against experimental data from Williamson’s lab. Findings show a notable lift coefficient increase, especially at higher flap angles. At β = 40o and 0o airfoil angle, lift was nearly three times greater than other cases. While drag also increased, it was less significant, indicating better aerodynamic efficiency. The lift-to-drag ratio improved notably at lower attack angles but declined slightly at higher angles due to turbulence and low-pressure zones. Overall, wavy airfoils with larger tail angles provide aerodynamic advantages, especially at low angles of attack, enhancing lift and fuel efficiency in aviation and marine contexts.