Study on the Behavior of Helmholtz Resonance in Different Size Bottles

The resonance is the specific response of system which is capable to vibrate with certain frequency to an external force acting with the same frequency. When air is blown across the open mouth of different bottles then air vibrate in a neck at resonant frequency. In this study we consider 5-5 bottles of different five types bottles having different of length of neck, radius of port, cross-sectional area of port and same volume (250ml). Resonance in different bottles was studied to determine how the volume of air cavity of different bottle affects the resonance. From calculated and experimental data, we found that the Helmholtz resonance frequency decreases with increase in volume and vice versa in each case of different bottles. From graph we also found that the calculated and experimental model are about 100% and 99% variability of the response data around its mean. The practical range for these different bottles is from about 256 to 512 Hz. This is about an octave plus a musical fifth near the middle of the musical instrument, so most simple musical tunes can be produced with such bottles.

Multiplicity of scision neutrons from density functional scission dynamics

The time evolution of the nuclear density of the fissioning system 240Pu during the scission process is obtained from the time-dependent superfluid local-density approximation (TDSLDA) to the density functional theory. A nuclear energy density functional based on the Skyrme force Skm* is used. The duration of the scission process Δt as well as the neck radius (rmin) of the ‘just-before scission’ configuration and the minimum separation (dmin) of the inner surfaces of the fragments in the ’immediately-after scission’ configuration were extracted in order to calculate the multiplicity of the scission neutrons (Vsc) using a phenomenological dynamical scission model (DSM). We find that Vsc=1.347, i.e. half of the prompt fission neutrons measured in the reaction 239Pu(nth; f) are released at scission. After scission, the fragments are left excited and with some extra deformation energy (mainly the heavy one). In this way we can account for the evaporation of the other half and for the emission of γ rays.

Influence of the surface viscous stress on the pinch-off of free surfaces loaded with nearly-inviscid surfactants

We analyze the breakup of a pendant water droplet loaded with SDS. The free surface minimum radius measured in the experiments is compared with that obtained from a numerical solution of the Navier–Stokes equations for different values of the shear and dilatational surface viscosities. This comparison shows the small but measurable effect of the surface viscous stresses for sufficiently small spatiotemporal distances from the breakup point, and allows to establish upper bounds for the values of the shear and dilatational viscosities. We study numerically the distribution of Marangoni and viscous stresses over the free surface as a function of the time to the pinching, and describe how surface viscous stresses grow in the pinching region as the free surface approaches its breakup. When Marangoni and surface viscous stresses are taken into account, the surfactant is not swept away from the thread neck in the time interval analyzed. Surface viscous stresses eventually balance the driving capillary pressure in the pinching region for small enough values of the time to pinching. Based on this result, we propose a scaling law to account for the effect of the surface viscosities on the last stage of temporal evolution of the neck radius.

Dynamics of Growth and Breakup of an Evaporating Pendant Drop

The growth and pinch-off dynamics of an evaporating pendant drop have been studied through direct numerical simulations. A coupled level-set and volume-of-fluid method is utilized to perform the simulations in an axisymmetric coordinate system. The dynamics of an evaporating pendant drop depends on the combined effects of buoyancy, capillary force, and the evaporation rate at the interface. The volumetric growth-rate of the drop decreases with the increase in degree of superheat of the surrounding medium, thereby enhances the pinch-off time. However, the departure diameter decreases with an increase in superheat. Limiting length and neck radius are not significantly affected due to the variation in degree of superheat. The heat transfer characteristics at different stages during the growth of a pendant drop have been analyzed for various values of superheat.

Time-Invariant Deformation of Blood During Necking on an Electrowetting Digital Microfluidic Platform

Recent developments in electrowetting-on-dielectric (EWOD) technology have expanded the possibilities for testing methods and investigation of blood. This work evaluated the development of necking geometry of whole blood on an EWOD-based digital microfluidic (DMF) platform. This was achieved by performing tensile tests on whole blood on an EWOD-based device, thereby inducing necking. A time-invariant method was used to evaluate the deformation of the tested dilutions, using minimum neck width and neck radius as two characteristic parameters of the necking geometry. Experiments were performed on blood diluted with phosphate-buffered saline (PBS) at dilutions of 1:20 and 1:10 by volume. Parameter measurements were obtained by recording microscope video of on-chip tensile tests and extracting the necking profile. Neck radius and neck width are obtained from the extracted necking profile and evaluated to compare results. Results from tensile tests on blood at different dilutions showed an exponential decrease in neck radius as neck width decreases. A four-parameter exponential model was fit to the collected data, showing that the 1:20 dilution had a higher neck radius to neck width ratio than the 1:10 dilution over a neck width interval of 0.3 mm to 1.7 mm, suggesting a viscosity effect on the necking geometry. The results demonstrate that the concentration of blood influences the necking profile when deformed under tension that is applied by electrowetting forces.

Macromolecular relaxation, strain, and extensibility determine elastocapillary thinning and extensional viscosity of polymer solutions

Delayed capillary break-up of viscoelastic filaments presents scientific and technical challenges relevant for drop formation, dispensing, and adhesion in industrial and biological applications. The flow kinematics are primarily dictated by the viscoelastic stresses contributed by the polymers that are stretched and oriented in a strong extensional flow field resulting from the streamwise gradients created by the capillarity-driven squeeze flow. After an initial inertiocapillary (IC) or viscocapillary (VC) regime, where elastic effects seem to play no role, the interplay of capillarity and viscoelasticity can lead to an elastocapillary (EC) response characterized by exponentially-slow thinning of neck radius (extensional relaxation time is determined from the delay constant). Less frequently, a terminal visco-elastocapillary (TVEC) response with linear decay in radius can be observed and used for measuring terminal, steady extensional viscosity. However, both IC/VC–EC and EC–TVEC transitions are inaccessible in devices that create stretched necks by applying a step strain to a liquid bridge (e.g., capillary breakup extensional rheometer). In this study, we use dripping-onto-substrate rheometry to obtain radius evolution data for unentangled polymer solutions. We deduce that the plots of transient extensional viscosity vs. Hencky strain (scaled by the respective values at the EC–TVEC transition) emulate the functional form of the birefringence–macromolecular strain relationship based on Peterlin’s theory. We quantify the duration and strain between the IC/VC–EC and the EC–TVEC transitions using measures we term elastocapillary span and elastocapillary strain increment and find both measures show values directly correlated with the corresponding variation in extensional relaxation time.

Exact calculation of axisymmetric capillary bridge properties between two unequal-sized spherical particles

A calculation method for the meridional profile of axisymmetric bridges between two spheres of different size is introduced in this manuscript. From geometrical data of the capillary bridge, such as the neck radius and boundary conditions (filling and contact angle), the shape of the capillary bridge is calculated analytically as a solution of the Young–Laplace equation. Its free surfaces, of constant mean curvature, may be classified into portions of nodoid, unduloid, and other limit cases. Moreover, other properties of the liquid bridge can be computed analytically, such as the associated capillary force exerted on the solid surfaces, liquid volume, mean curvature, and free surface area.

The SmCo5 Intermetallic Compound Sintering

The SmCo5has three sintering stages using spheres (0.6 – 1.0 mm diameter) at temperatures between 1030 and 1200 °C. During the first stage the neck radius increases as X2~ t for less than 1200 °C temperature, the exponent is 3 at 1200 °C. Interdiffusion is sintering mechanism for exponent of 2. Sm diffuses from inside to the surface, where it is oxidized and oxides fills the neck between the spheres. Co diffuses through the oxides. At 1200 °C the sintering mechanism is evaporation-condensation of Sm. The activation enthalpy of the first stage is 582 kJmol-1for temperatures above 1130 °C and 210 kJmol-1bellow 1130 °C, respectively. The second stage is characterized by a plateau where the neck growth is arrested. The small pores in the neck and in the sphere surface layer (formed during the first stage) shrink. When these pores disappear a continuous α-Co layer forms and the third stage starts. It is essential growth of the neck formed by dense Co layer. The law of sintering is X4~ t. The activation enthalpy (276 kJmol-1at temperatures above 1130 °C) closes the activation enthalpy of Co self-diffusion. This (together with the exponent of 4) suggests that the Co layer plays a role similar to that of a liquid film. Making slight changes in the chemical composition of the alloys and substituting an argon atmosphere to vacuum have no influence or stages and sintering mechanisms.

Plethora of transitions during breakup of liquid filaments

Thinning and breakup of liquid filaments are central to dripping of leaky faucets, inkjet drop formation, and raindrop fragmentation. As the filament radius decreases, curvature and capillary pressure, both inversely proportional to radius, increase and fluid is expelled with increasing velocity from the neck. As the neck radius vanishes, the governing equations become singular and the filament breaks. In slightly viscous liquids, thinning initially occurs in an inertial regime where inertial and capillary forces balance. By contrast, in highly viscous liquids, initial thinning occurs in a viscous regime where viscous and capillary forces balance. As the filament thins, viscous forces in the former case and inertial forces in the latter become important, and theory shows that the filament approaches breakup in the final inertial–viscous regime where all three forces balance. However, previous simulations and experiments reveal that transition from an initial to the final regime either occurs at a value of filament radius well below that predicted by theory or is not observed. Here, we perform new simulations and experiments, and show that a thinning filament unexpectedly passes through a number of intermediate transient regimes, thereby delaying onset of the inertial–viscous regime. The new findings have practical implications regarding formation of undesirable satellite droplets and also raise the question as to whether similar dynamical transitions arise in other free-surface flows such as coalescence that also exhibit singularities.