Construction of reliable dynamic models of nanostructures is an important task for design procedures of different nanoresonator devices. Such theoretical models allow as to perform different numerical experiments, which is the key point in the development of advanced nanodevices. This paper presents a new nanoresonator model based on the axial vibration of the elastic multi-nanorod system. It is assumed that the system of multiple nanorods is embedded in an elastic medium. The governing equations of motion of a coupled multi-nanorod system are derived using the Hamilton’s principle, the nonlocal elastic constitutive relation, and Bishop’s rod theory, where effects of inertia of the lateral motion and the shear stiffness are considered. Exact closed form solutions for natural frequencies are obtained for one and multiple nanorod systems with different boundary conditions. Then, results for natural frequencies obtained by the finite difference method are compared with the results obtained analytically. Effects of nonlocal parameter, different rod theories, number of nanorods and stiffness coefficient of an elastic medium on natural frequencies are examined through several numerical examples.

This paper deals with an analysis of a two-dimensional viscous fluid flow between the two parallel plates inclined with respect to the horizontal plane, where the lower plate is heated and the upper one is cooled. The temperature difference between the plates is gradually increased during a certain time period after which it is temporarily constant. The temperature distribution on the lower plate is not constant in x-direction, there is a longitudinal sinusoidal temperature variation imposed on the mean temperature. We have investigated the wave number and amplitude influence of this variation on the subcritical stability and the onset of the Rayleigh-Bénard convective cells, by direct numerical simulation of 2D Navier-Stokes and energy equation.

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The goal of this paper is to establish the optimal operating regime of the observed perforated plate air/water heat exchanger in a wide range of parameters. The experimental investigation was carried out in a package of three perforated plates which were placed in the experimental chamber and heated by hot water. A fan with the variable air volume flow was connected to the experimental chamber, so the air flow rates varied from 100 to 300 m 3 /h, while the water flow varied from 0.03 to 0.06 m 3 /h. The thermocouples were attached to the surface of the middle perforated plate in the package along its upwind and downwind sides, as well as at the inlet and outlet of the chamber and between the perforated plates. During each experiment, the readings of thermocouples were recorded alongside with the air and water volume flow and temperatures of water at the inlet and outlet of the chamber. In order to predict the performance of the observed perforated plate heat exchanger, NTU-Effectiveness analysis was performed on the basis of the experiment results and analytical relations. Experimental results showed that the effectiveness of the perforated plate heat exchanger can be calculated the same as for the concentric tube counter flow. At the end of the paper, the optimal operating point in the range of varied parameters was determined.

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