Submersed superhydrophobic surfaces exhibit great potential for reducing flow resistance in microchannels and drag of submersed bodies. However, the low stability liquid-air interfaces on those limits scope their application, especially under high liquid pressure. In this paper, we first investigate wetting states hydrophobic with one-level structure hydrostatic Different equilibrium based free-energy minimization are formulated, stabilities analyzed as well. Then, by comparison existing...

Particle Image Velocimetry (PIV), pressure, and noise measurements are used to study the effect of modifications tongue impeller geometries on flow structure resulting in a centrifugal pump. It is demonstrated that primary sources associated with interactions nonuniform outflux from (jet/wake phenomenon) tongue. Consequently, significant reduction achieved by increasing gap between up about 20 percent radius. Further increase affects performance adversely minimal impact level. When narrow,...

Maps of pressure distributions computed using PDV data, combined with noise and local measurements, are used for identifying primary sources in a centrifugal pump. In the vicinity impeller minima occur around blade near vortex train generated as result non-uniform outflux from impeller. The everywhere also varies depending on orientation relative to tongue. Noise peaks when difference across tongue is maximum, probably due oscillations, wake impinges tip

This paper describes a series of quantitative flow visualization experiments within the volute centrifugal pump by implementing “Particle Displacement Velocimetry” method (PDV or PIV). Part A focuses on measurement procedures and includes an uncertainty analysis. technique involves illuminating sections field with pulsed laser sheets while seeding water microscopic, neutrally buoyant particles containing imbedded fluorescent dye. By pulsing more than once recording single photograph each...

Velocity distributions determined by using Particle Displacement Velocimetry are used for computing the pressure field within volute of a centrifugal pump. It is shown that blade-tongue interactions and nonuniform outflux from impeller primary contributors to local fluctuations far noise. Consequently, slight increase in space between tongue causes significant changes flow structure reductions resulting The impact as long tongue-impeller gap less than 20 percent radius. also vorticity...

The mass flux at the surface of a drop in an immiscible host liquid is dictated by composition surface. In binary system, this essentially constant time and equals solubility constituent liquid. This situation has been treated classic study Epstein Plesset ( J. Chem. Phys. , vol. 18, 1950, pp. 1505–1509). very different for ternary higher-order systems which, due to mutual interaction constituents, their concentration markedly differs from respective solubilities depends on time. paper...

PDV is used for measuring the velocity within volute of a centrifugal pump at different impeller blade orientations, on and off design conditions. It demonstrated that flow “pulsating” depends location relative to tongue. The leakage also orientation increases with decreasing rate. near dominated by jet/wake phenomenon. Differences in outflux from impeller, resulting changes inflow rate, occur primarily exit. Away tongue distributions vθ mostly agrees assumption ∝ 1/r. Sites prone high...

This letter reports on the tunable wetting behavior of poly(dimethylsiloxane) (PDMS) via combination nanostructuring and plasma treatment. The PDMS is first micro/nanostructured by an integrated casting process. Subsequently, inductively coupled used to modify siloxanes' surface chemistry. Sulfur hexafluoride, fluoroform, as well octafluorocyclobutane were applied treat samples successively. By optimizing treatment parameters, wettability siloxane was observed, i.e., superhydrophilicity...

Diffusive processes exhibit a strong dependence on history effects. For gas bubble at rest in liquid, such effects arise when the concentration of dissolved surface, dictated by Henry's law, depends time. In this paper we consider several situations. An oscillating ambient pressure field causes occurrence rectified diffusion into or out bubble. Unlike previous investigators, who considered opposite limit, study process for conditions length is larger than radius. It found that are important...

A horizontally integrated model for bubble plumes in stratified environments, including inlet conditions, finds that the maximum plume momentum height cannot be identified with neutral buoyancy height, which it is always less than. These results are agreement existing observations.

This paper reports a single-step process to fabricate superhydrophobic micro/nano dual-scale (MNDS) poly(dimethylsiloxane) (PDMS) membrane replicated directly from ultra-low-surface-energy MNDS silicon substrate at high temperature without surfactant coating. surface with ultra-low energy was simply fabricated by an improved deep reactive ion etching (DRIE) process. The huge reduction of and the formation high-density nanostructures (i.e. nanotips) on well-designed microstructures inverted...

The loss of buoyancy because dissolution is mitigated or enhanced by changes in ambient liquid density. A scaling analysis identifies three parameters: rate vs plume rise time, the effect dissolved material on density, and drop bubble velocity velocity.

In this paper, we present the tunable wetting behavior of Poly(dimethylsiloxane) (PDMS) by nanostructuring and plasma treatments, which shows stable superhydrophobicity superhydrophilicity. The PDMS film with high-density nanoporous was prepared replica molding black silicon surface fabricated an improved deep reactive ion etching (DRIE) process. This simple can increase roughness reduce energy PDMS. conventional equipment for micro fabrication (i.e. inductively couple etcher) used to...

Particle Image Velocimetry (PIV), pressure and noise measurements are used to study the effect of modifications tongue impeller geometries on flow structure resulting in a centrifugal pump. It is demonstrated that primary sources associated with interactions non-uniform outflux from (jet/wake phenomenon) tongue. Consequently, significant reduction achieved by increasing gap between up about 20% radius. Further increase affects performance adversely minimal impact level. When narrow,...