Compressible potential flows around round bodies: Janzen–Rayleigh expansion inferences

The subsonic, compressible, potential flow around a hypersphere can be derived using the Janzen–Rayleigh expansion (JRE) of the flow potential in even powers of the incident Mach number ${\mathcal {M}}_\infty$ . JREs were carried out with terms polynomial in the inverse radius $r^{-1}$ to high orders in two dimensions, but were limited to order ${\mathcal {M}}_\infty ^{4}$ in three dimensions. We derive general JRE formulae for arbitrary order, adiabatic index and dimension. We find that powers of $\ln (r)$ can creep into the expansion, and are essential in the three-dimensional (3-D) sphere beyond order ${\mathcal {M}}_\infty ^{4}$ . Such terms are apparently absent in the 2-D disk, as we verify up to order ${\mathcal {M}}_\infty ^{100}$ , although they do appear in other dimensions (e.g. at order ${\mathcal {M}}_\infty ^{2}$ in four dimensions). An exploration of various 2-D and 3-D bodies suggests a topological connection, with logarithmic terms emerging when the flow is simply connected. Our results have additional physical implications. They are used to improve the hodograph-based approximation for the flow in front of a sphere. The symmetry-axis velocity profiles of axisymmetric flows around different prolate spheroids are approximately related to each other by a simple, Mach-independent scaling.

A Study of Yielding and Plasticity of Rapid Prototyped ABS

In this article, the yielding and plastic flow of a rapid-prototyped ABS compound was investigated for various plane stress states. The experimental procedures consisted of multiaxial tests performed on an Arcan device on specimens manufactured through photopolymerization. Numerical analyses were employed in order to determine the yield points for each stress state configuration. The results were used for the calibration of the Hosford yield criterion and flow potential. Numerical analyses performed on identical specimen models and test configurations yielded results that are in accordance with the experimental data.

Effect of electro-kinetic processes on filtration of fluids and gas in porous medium

The paper reviews the fluid and gas flow in the porous medium considering electro-kinetic phenomena – electro-phoresis and electro-osmosis, as well as the charges associated with them. These phenomena are due to the double electric layer on the border of division of disperse system phases. Electro-kinetic phenomena are follows: electro-phoresis, electro-osmosis, flow potential (Quincke effect) and sedimentation potential (Dorn effect). The formulas for the motion of fluid and gas in porous medium considering the properties of porous medium and saturating them fluids, as well as the interaction between them, which is described with electro-kinematic phenomena, have been obtained. Obtained formulas have been evaluated via the results of laboratory researches.

Акустоэлектрический преобразователь на основе электрокинетического явления потенциал течения

A mathematical model of an acoustoelectric transducer based on the use of the electrokinetic phenomenon of the flow potential is proposed. It is shown theoretically that the flow potential increases in proportion to the strength of the constant electric pumping field, which is confirmed experimentally. The described converter has variable sensitivity. Rather large values of the sensitivity of an electrokinetic microphone have been obtained experimentally. The results of the work can be used in the design of acoustoelectric transducers.

Computational Analysis of Co-Flow Potential Core Degradation of a Chevron Nozzle

In this paper, the characteristics of co-flowing jet in circular and chevron nozzle was studied. Three-dimensional chevron nozzle was designed with the saw tooth pattern to reduce the exhaust noise and infrared signature. Co-flow analysis of the nozzles was carried out using ANSYS CFX software. The jet performance of chevron nozzle was compared with that of a circular nozzle. The potential core decay length of co-flow circular and chevron nozzle was studied at two different Mach number of 0.6 and 1. The results shown that the potential core decay reduced for co-flow chevron nozzle along axial and radial directions.