Outer Acoustic Streaming Flow Driven by Asymmetric Acoustic Resonances

While boundary-driven acoustic streaming resulting from the interaction of sound, fluids and walls in symmetric acoustic resonances have been intensively studied in the literature, the acoustic streaming fields driven by asymmetric acoustic resonances remain largely unexplored. Here, we present a theoretical and numerical analysis of outer acoustic streaming flows generated over a fluid–solid interface above which a symmetric or asymmetric acoustic standing wave is established. The asymmetric standing wave is defined by a shift of acoustic pressure in its magnitude, i.e., S0, and the resulting outer acoustic streaming is analyzed using the limiting velocity method. We show that, in symmetric acoustic resonances (S0 = 0), on a slip-velocity boundary, the limiting velocities always drive fluids from the acoustic pressure node towards adjacent antinodes. In confined geometry where a slip-velocity condition is applied to two parallel walls, the characteristics of the obtained outer acoustic streaming replicates that of Rayleigh streaming. In an asymmetric standing wave where S0 ≠ 0, however, it is found that the resulting limiting velocity node (i.e., the dividing point of limiting velocities) on the slip-velocity boundary locates at a different position to acoustic pressure node and, more importantly, is shown to be independent of S0, enabling spatial separation of acoustic radiation force and acoustic streaming flows. The results show the richness of boundary-driven acoustic streaming pattern variations that arise in standing wave fields and have potentials in many microfluidics applications such as acoustic streaming flow control and particle manipulation.

Ordinary Versus Novel Particle With the Example of Their Spontaneous Transition

The bicubic equation of particle limiting velocity formalism yields three solutions c1, c2 and c3, (primary, secondary and tertiary) limiting velocities in terms of the congruent parameter  which is defined in terms of m, v, and E, respectively being particle mass, velocity and energy. The bicubic equation discriminant D is given in terms of the congruent parameter z(m). When one has z2(m) ≤ 1 with the discriminant satisfying D ≤ 0 then we are talking about limiting velocities of ordinary particles. Good examples are the relativistic particles such as electron, neutrino,etc., with luminal limiting velocity c3 = c and calculated superluminal c2, and imaginary superluminal c1, all corresponding to the real particle energy. On the specific level, the situations like these, we discuss in the muon neutrino velocities with the OPERA detector and the electron velocities from the 2010 Grab Nebula Flare. The z(m) = 1 value separates the ordinary particles from novel particles, associated with D ⪰ 0 and z2 ⪰ 1 with new novel particle limiting velocity solutions c1, c2 and c3 which depend, in addition to z(m), also on the congruent angle α(m), nonlinearly related to z(m). These solutions are discussed on the newly defined sterile neutrino which here is modeled as an ordinary particle with z2 ⪯ 1 spontaneously transiting via z(m) = 1 into the modeled novel sterile neutrino with z2 ⪰ 1. All ordinary and novel particles limiting velocities carry real particle energies; the ordinary particle limiting velocity solutions being in quadratic forms, while the novel particle limiting velocity solutions being respectively, in quadratic complex form, linear complex form, and just congruent angle α complex quadratic form.

Polarization Domain Dynamics of Barium Titanate Ultrathin Films Using Piezoresponse Force Microscopy.

Piezoresponse force microscopy is used to study the velocity of the polarization domain wall in ultrathin ferroelectric barium titanate films grown on strontium titanate substrates by molecular beam epitaxy. The electric field due to the cone of the atomic force microscope tip is proposed as the dominant electric field of the tip in thin films for domain expansion at lateral distances greater than about one tip diameter away from the tip. The velocity of the domain wall under the applied electric field by the tip in barium titanate for thin films (less than 40 nm) followed an expanding process given by Merz’s law. The material constants in a fit of the data to Merz’s law for very thin films are reported as about 4.2 KV/cm for activation field, Ea, and 0.05 nm/s for limiting velocity, v∞. These material constants showed a dependence on the level of strain in the films but no fundamental dependence on thickness.

MINIMUM LAP TIME CALCULATION USING MATLAB

Formula Student car, to participate in different Formula Student events. Though the car was designed and all designed systems and components were validated using Static Simulation, but it was not known how would car perform on the actual track. By using different dynamic simulation methods and MATLAB programming, team has tried to understand the vehicle behaviour on track. One of the methods used by the team was, to calculate the limiting velocity for each curve on the track and to calculate the time required by the car to complete one Endurance lap of Formula Bharat 2020. This was achieved by making a mathematical model and using concepts of vehicle Dynamics. In the study different cases of the track are also discussed and how does the car behave at different portion of the track is clearly explained in the study. This helps the driver to handle the car properly. As with this information driver would be able to know how his car would behave at different corners of the track.

Complex Limiting Velocity Expressions as Likely Characteristics of Dark Matter Particles

Many astrophysical and cosmological observations suggest that the matter in the universe is mostly of the dark matter type whose behavior goes beyond the Standard Model description. Hence it is justifiable to take a drastically different approach to the dark matter particles which is here done through the bicubic equation of limiting particle velocity formalism. The bicubic equation discriminant $D$ in this undertaking satisfy $D\succeq 0 $ determined by the congruent parameter $z$ satisfying $z^{2}\succeq 1$, where formally $z(m)=3\sqrt{3}mv^{2}/2E$, \ with $m$, $v$, and $E$ being respectively, particle mass, velocity and energy. Also nonlinearly related to the the particle congruent parameter $z$ is the particle congruent angle $% \alpha $ . These two dimensionless\ parameters $z$ \ and $\alpha $ simplify expressions in the bicubic equation limiting particle velocity formalism when evaluating the three particle limiting velocities, $c_{1},$ $c_{2}$\ and $c_{3},$ (primary, obscure and normal) in terms of the ordinary particle velocity, $v$. Corresponding to these limiting velocities \ one then deduces, with equal values, dark matter particle energies $E\left(c_{1}\right) $, $E\left( c_{2}\right) $ and $E\left( c_{3}\right) $. The exemplary values of the congruent parameters are in these regions, $1\preceq z\prec 3\sqrt{3}$ $/2$ and $\pi /2\succeq \alpha \succeq \pi /3$ . Already within these ranges of congruent parameters, the bicubic formalism yields for squares of particle limiting velocities that $c_{1}^{2}$ and $c_{2}^{2}$ are complex conjugate to each other, $c_{1}^{2\ast }=c_{2}^{2}$ ,and that $% c_{3\text{ }}^{2}$is real. The imaginary portions of $c_{1}^{2}$ and $% c_{2}^{2}$ do not change the realities of numerically equal to each other dark matter energies $E\left( c_{i}\right) ,i=1,2,3.$ In fact, real $E\left(c_{1,2}\right) $ energies can be equally evaluated with $c_{1,2}^{2}$ or $% \func{Re}$ $c_{1,2}^{2}$ or even with $\func{Im}c_{1,2}^{2}$ so that in new notation, $E\left( _{1,2}^{2}\right) =E\left( \func{Re}c_{1,2}^{2}\right) =E\left( \func{Im}c_{1,2}^{2}\right) $ $=E\left( c_{3}^{2}\right) $ all with the same real values. However, in these notations, the real particle momenta are $\overrightarrow{p}\left( (\func{Re}c_{1,2}^{2}\right) $ and $\\overrightarrow{p}\left( (c_{3}^{2}\right) $, defined with respective energies and, while in similar forms , numerically are different from each other.

Numerical Simulation of Boundary-Driven Acoustic Streaming in Microfluidic Channels with Circular Cross-Sections

While acoustic streaming patterns in microfluidic channels with rectangular cross-sections have been widely shown in the literature, boundary-driven streaming fields in non-rectangular channels have not been well studied. In this paper, a two-dimensional numerical model was developed to simulate the boundary-driven streaming fields on cross-sections of cylindrical fluid channels. Firstly, the linear acoustic pressure fields at the resonant frequencies were solved from the Helmholtz equation. Subsequently, the outer boundary-driven streaming fields in the bulk of fluid were modelled while using Nyborg’s limiting velocity method, of which the limiting velocity equations were extended to be applicable for cylindrical surfaces in this work. In particular, acoustic streaming fields in the primary (1, 0) mode were presented. The results are expected to be valuable to the study of basic physical aspects of microparticle acoustophoresis in microfluidic channels with circular cross-sections and the design of acoustofluidic devices for micromanipulation.