[en] We revisit a classic demonstration for surface tension in soap films and introduce a more striking variation of it. The demonstration shows how the film, pulling uniformly and normally on a loose string, transforms it into a circular arc under tension. The relationship between the surface tension and the string tension is analysed and presented in a useful graphical form. (letters and comments)

[en] A Skeleton Table and simple interpolation equation for the surface tension of light water was developed by the Working Group III of the International Association for the Properties of Steam and is recommended as an International Standard. The Skeleton Table is based on all known measurements of the surface tension and individual data were weighted corresponding to the accuracy of the measurements. The form of the interpolation equation is based on a physical concept. It represents an extension of van der Waals-equation, where the exponent conforms to the 'Scaling Laws'. In addition for application purposes simple relations for the Laplace-coefficient and for the density difference between the liquid and gaseous phases of light water are given. The same form of interpolation equation for the surface tension can be used for heavy water, for which the coefficients are given. However, this equation is based only on a single set of data. (orig.)

[en] Highlights: • Development of a unified criterion for breakup considering all forces acting on the droplet. • Proposing a new breakup map using the liquid Capillary number. • Proposing an effective We number which includes the effects of Re number and density ratio. • Model validation against several experimental and numerical data for droplet breakup. - Abstract: The determination of the critical We_g number separating the different breakup regimes has been extensively studied in several experimental and numerical works, while empirical and semi-analytical approaches have been proposed to relate the critical We_g number with the Oh_l number. Nevertheless, under certain conditions, the Re_g number and the density ratio ε may become important. The present work provides a simple but reliable enough methodology to determine the critical We_g number as a function of the aforementioned parameters in an effort to fill this gap in knowledge. It considers the main forces acting on the droplet (aerodynamic, surface tension and viscous) and provides a general criterion for breakup to occur but also for the transition among the different breakup regimes. In this light, the present work proposes the introduction of a new set of parameters named as We_g,eff and Ca_l monitored in a new breakup plane. This plane provides a direct relation between gas inertia and liquid viscosity forces, while the secondary effects of Re_g number and density ratio have been embedded inside the effective We_g number (We_g,eff)

[en] Published in summary form only

[en] We discuss the influence of several definitions of the dividing surface on the size dependence of surface tension and surface stress. Among others we apply the original definition of GIBBS for the 'surface of tension' (SOT) and the 'equimolecular dividing surface' (EMDS). We show that from physical reasons the surface tension must only include curvature terms up to the quadratic term. The considerations are illustrated for microclusters of simple geometric configurations. (orig.)

[en] We present an exact relation among the kinetic, potential and surface tension energies of a solitary wave in deep water in all dimensions. We deduce its non-existence in the absence of the effects of surface tension, provided that gravity acts in a direction opposite to what is physically realistic. (fast track communication)

[en] This work proposes a multi-scale simulation method that can simulate filling during the micro-injection molding process. The multiscale simulation is comprised of two steps. In the first step, the macro-scale flow is analyzed using the conventional method. In the second step, the micro-scale simulation is conducted taking the slip and surface tension into consideration to investigate the filling of microcavity. Moreover, a conservative level set method is employed to accurately track the flow front. First, numerical tests have been done for circular micro-channels. The results show that slip and surface tension play important roles in the micro-regime. Second, to verify the multi-scale method, filling of a thin plate with micro-channel patterns has been simulated. The results show that the proposed multi-scale method is promising for micro-injection molding simulations

[en] Sintering diagrams remove the ambiguity in criterion for determining the sintering mechanisms, unlike the classical exponent method. However, data on a large number of material properties are required for constructing the diagrams. One such property on which data for several materials are difficult to come by in the literature is the surface energy. Effort has, therefore, been made to evaluate it by correlating surface energy with available surface diffusion data. In the work presented here, it is found that the surface energy is directly proportional to the logarithm of the surface diffusivity. This is based on phenomenological considerations and hence is not affected by atomistics of the diffusion process. The proportionality holds for a single system with variation in temperature. The data available in the literature are found to obey this relationship. (author)

[en] Through-wafer electrical interconnection is a critical technology for advanced packaging. In this paper, a novel capillary-effect-based solder pump has been proposed and analyzed, which could produce interconnects through and between silicon dies. The principle of this pump is to use the surface tension of a molten solder, introduced in the form of balls, to drive sufficient material into a deep reactive-ion etched hole to form a through-wafer conductive path. The solder pump structure uses unwettable through-wafer holes of different diameters together with wettable metallization on two dies to provide the pressure differential and flow path. Using multiple feed holes and a single via hole complete through-wafer interconnects are demonstrated

[en] The sessile-drop method is used to measure the surface tension and density of liquid indium and uranium under high vacuum. Measurements are made over the temperature range 156-500C for In and at the melting point for U. Surface oxides are efficiently removed with a glow discharge system. Drop profiles are captured by photograph and processed using nonlinear regression to yield the surface tension and density. In this regression procedure, normal distances from calculated profiles to data points are minimized. For indium, the density and surface tension measurements yield ρ_mp=7.05x10³ kg/m³, dρ/dT=-0.776 kg/m³·C, and γ_mp=0.568 N/m, dγ/dT=-9.45x10^-5 N/m·C. The results for uranium at the melting point are ρ_mp=17.47x10³ kg/m³ and γ_mp=1.653 N/m