Mathematical Study of Nonlinear Mixed Convection Unsteady Flow in a Parallel Plate Inclined Channel in the Proximity of Time Periodic Boundary Conditions: Flow Reversal

This report is executed to examine the task of assimilating parameters on bipartite convection stream structure in a sloped pipeline while certain plate is disorderly warmed. The dictating motivation and energy identifications are ascertained and consequent expressions for thermal reading, liquid movement, fanning friction and stress flatten are acquired. The purpose of non-linear Boussinesq simulation is to escalate liquid movement, inverse stream generation at the channel plates, stress flatten, and fanning factor. In particular, the liquid motion escalates at the channel left portion and depletes at the channel right portion with the progress of time. A particular case of our development shows an excellent compromise with the previous consequences in the literature.

Prototyping and Study of Mesh Turbomachinery Based on the Euler Turbine

This paper presents a scientific development aimed at improving the efficiency of turbomachines through the joint use of rotary-vane and vortex workflows. In the well-known Euler turbine, the rotor flow channels represent a set of curved pipes. The authors propose to consider in more detail the possibilities of using such rotating pipes in the implementation of an ejection (vortex) workflow. A hybrid pump was considered with the conclusion that its workflow can be described using two Euler equations. The results of computer simulation indicate that hybrid turbomachines are promising. The use of additive technology allowed the creation of micromodels of the Euler turbine with various rotor designs. Laboratory hydraulic tests showed that the liquid inlet to the rotor is possible in pulse mode. Laboratory tests of micromodels using compressed air showed that gas (or liquid) motion through curved pipes could be carried out from the rotor periphery to its center and then back, albeit through another curved pipe. The research results demonstrated that the scientific and technical potential of the Euler turbine is not yet fully unlocked, and research in this direction should continue. The study results are applicable in various industries including the energyeconomy, robotics, aviation, and water transport industries.

Entropy generation in MHD free convection of nanoliquid within a square open chamber with a solid body

Purpose The study aims to investigate magnetohydrodynamics thermal convection energy transference and entropy production in an open chamber saturated with ferrofluid having an isothermal solid block. Design/methodology/approach Analysis of thermal convection phenomenon was performed for an open chamber saturated with a nanofluid having an isothermal solid unit placed inside the cavity with various aspect ratios. The left border temperature is kept at Tc. An external cooled nanofluid of fixed temperature Tc penetrates into the domain from the right open border. The nanofluid circulation is Newtonian, incompressible, and laminar. The uniform magnetic field of strength B at the tilted angle of γ is applied. The finite volume technique is used to work out the non-linear equations of liquid motion and energy transport. For Rayleigh number (Ra=1e+7), numerical simulations were executed for varying the solid volume fractions of the nanofluid (ϕ = 0.01–0.04), the aspect ratios of a solid body (As = 0.25–4), the Hartmann number (Ha = 0–100), the magnetic influence inclination angle (γ = 0–π/2) and the non-dimensional temperature drop (Ω = 0.001–0.1) on the liquid motion, heat transference and entropy production. Findings Numerical outcomes are demonstrated by using isolines of temperature and stream function, profiles of mean Nusselt number and entropy generations. The results indicate that the entropy generation rate and mean Nu can be decreased with an increase in Ha. The inner solid block of As = 0.25 reflects the maximum heat transfer rate in comparison with other considered blocks. The addition of nano-sized particles results in a growth of energy transport and mean entropy generations. Originality/value An efficient computational technique has been developed to solve natural convection problem for an open chamber. The originality of this research is to scrutinize the convective transport and entropy production in an open domain with inner body. The outcomes would benefit scientists and engineers to become familiar with the investigation of convective energy transference and entropy generation in open chambers with inner bodies, and the way to predict the energy transference strength in the advanced engineering systems.

The influence of the structure of laminar flows on the characteristics of equipment

The new method of visual diagnostics of liquid motion processes in physical models showed a high degree of the flow structure organization. Visual pictures made it possible to develop a hydraulic experiment to reveal the dimensions of the transverse structure in the form of layers and zones of flow separation from the channel walls. Visual diagnostics is the basis for comprehensive equipment design. Visual studies of the flow structure provide information for improving equipment by changing the geometry of the flow paths. Hydraulic studies show the change in the resistance of the equipment channels. Based on the results of visual and hydraulic studies, the wave character of the distribution of the pulsation velocity components was revealed. The regularities of the velocity distribution allow predicting the minimum or maximum values of the resistances of the flow paths of the equipment.

Theoretical Justification of Plant Stems Vibro-Cutting in Dense Environment

The article considers the issue related to the disclosure of the reasons for the abrupt reduction of resistance force factors in case of plants stems vibro-cutting in dense medium through theory-based investigations. The computation scheme of the liquid motion in the vicinity of vibro-blade has been recommended, which enabled to derive differential equation of the motion resulted under the impact of interaction forces between the vibro-blade and environment. It has been proved, that the liquid in the vibro-blade vicinity is subjected to rapid damped oscillation, due to which the environmental resistance forces and the energy consumption rates are reduced in about 20 times against the same indices recorded in case of vibrationless cutting.

FORCED VIBRATIONS OF A INHOMOGENEOUS ORTHOTROPIC CYLINDRICAL SHELL STIFFENED WITH A CROSS-SYSTEM OF RIBS IN LIQUID

In the paper we study forced vibrations of an orthotropic cylindrical shell inhomogeneous in thickness and stiffened with a cross-system of ribs in liquid under the action of inner radial pressure pulsating in time. Based on Hamilton – Ostrogradsky variational principle, we construct a system of equations to determine the displacements of the mid-surface points of an orthotropic cylindrical shell inhomogeneous in thickness and stiffened with a cross-system of ribs under dynamical interaction with liquid. Surface loads acting on the cylindrical shell inhomogeneous in thickness and stiffened with a cross-system of ribs as viewed from liquid are determined from the solutions of liquid motion equations written in potentials. Analytic formulas for finding the displacements of the midsurface points of a liquid-contacting orthotropic cylindrical shell inhomogeneous in thickness and stiffened with a cross-system of ribs, were obtained.

Surface-Tension-Confined Channel with Biomimetic Microstructures for Unidirectional Liquid Spreading

Unidirectional liquid spreading without energy input is of significant interest for the broad applications in diverse fields such as water harvesting, drop transfer, oil–water separation and microfluidic devices. However, the controllability of liquid motion and the simplification of manufacturing process remain challenges. Inspired by the peristome of Nepenthes alata, a surface-tension-confined (STC) channel with biomimetic microcavities was fabricated facilely through UV exposure photolithography and partial plasma treatment. Perfect asymmetric liquid spreading was achieved by combination of microcavities and hydrophobic boundary, and the stability of pinning effect was demonstrated. The influences of structural features of microcavities on both liquid spreading and liquid pinning were investigated and the underlying mechanism was revealed. We also demonstrated the spontaneous unidirectional transport of liquid in 3D space and on tilting slope. In addition, through changing pits arrangement and wettability pattern, complex liquid motion paths and microreactors were realized. This work will open a new way for liquid manipulation and lab-on-chip applications.

Driving mechanism of dragonfly’s wing flapping pattern for liquid circulation inside wing

Flying animals can inspire practical approaches to a more advanced way of flying. Dragonflies demonstrate a special flapping pattern in which their wings perform torsional movement while flapping, which is different from that of birds. This flapping pattern is referred to as nonsynchronous flapping in this article. We present a hypothesis that nonsynchronous flapping provides a driving force for enhancing the haemolymph circulation inside dragonfly wings. To support this hypothesis, a controlled experiment was designed and conducted with living dragonflies. By observing the liquid motion inside the vein within free flapping wings and restricted wings of living dragonflies, this hypothesis was supported. A mathematical model of the flapping wing was built and numerically studied to further support the function of the nonsynchronous flapping pattern in driving the circulation. With these studies, a theoretical explanation for the mechanism of enhancing the haemolymph circulation by nonsynchronous flapping was provided.

Investigation of the Influence of Liquid Motion in a Flow-Based System on an Enzyme Aggregation State with an Atomic Force Microscopy Sensor: The Effect of Glycerol Flow

Atomic force microscopy is employed to study the influence of the motion of a glycerol solution through a coiled (spiral-wound) polymeric communication pipe on the aggregation state of a protein, with the example of a horseradish peroxidase (HRP) enzyme. The measuring cell with the buffered solution of the protein was placed within the experimental setup over the pipe coil, through which glycerol was pumped. It is demonstrated that, in such a system, the flow of a non-aqueous liquid (glycerol) leads to a change in the physicochemical properties of a protein, whose solution was incubated in the measuring cell placed over the coil. Namely, changes in both the adsorbability onto mica and the aggregation state of the model HRP protein were observed. As glycerol-containing liquids are commonly used in biosensor operations, the results reported herein can be useful to the development of biosensor systems, in which polymeric communications are employed in sample delivery and thermal stabilization systems. The data obtained herein can also be of use for the development of specified hydrodynamic models.