Viscous Water Flow Research Articles

Strawberry fruit skins are far more permeable to osmotic water uptake than to transpirational water loss

Water movements through the fruit skin play critical roles in many disorders of strawberry (Fragaria × ananassa Duch.) such as water soaking, cracking and shriveling. The objective was to identify the mechanisms of fruit water loss (dry skin, transpiration) and water uptake (wet skin, osmosis). Fruits were held above dried silica gel or incubated in deionized water. Water movements were quantified gravimetrically. Transpiration and osmotic uptake increased linearly with time. Abrading the thin cuticle (0.62 g m-2) increased rates of transpiration 2.6–fold, the rates of osmotic uptake 7.9-fold. The osmotic potential of the expressed juice was nearly the same for green and for white fruit but decreased in red fruit stages. Fruit turgor was low throughout development, except for green fruit. There was no relationship between the rates of water movement and fruit osmotic potential. The skin permeance for transpiration and for osmotic uptake were both high (relative to other fruit species) but were two orders of magnitude greater for osmotic uptake than for transpiration. Incubating fruit in isotonic solutions of osmolytes of different sizes resulted in increases in fruit mass that depended on the osmolyte. The rate of osmotic uptake decreased asymptotically as molecular size of the osmolyte increased. When transpiration and osmotic uptake experiments were conducted sequentially on the same fruit, the rates of transpiration were higher for fruit previously incubated in water. Fluorescence microscopy revealed considerable microcracking in a fruit previously incubated in water. Our findings indicate that the high permeance for osmotic uptake is accounted for by an extremely thin cuticle and by viscous water flow through microcracks and along polar pathways.

안정적이고 이방성한 빙결 모델링을위한 암시적 비압축성 유체와 얼음 입자간의 상호작용 기법

In this paper, we propose a new method to stable simulation the directional ice shape by coupling of freezing solver and viscous water flow. The proposed ice modeling framework considers viscous fluid flow in the direction of ice growth, which is important in freezing simulation. The water simulation solution uses the method of applying a new viscous technique to the IISPH(Implicit incompressible SPH) simulation, and the ice direction and the glaze effect use the proposed anisotropic freezing solution. The condition in which water particles change state to ice particles is calculated as a function of humidity and new energy with water flow. Humidity approximates a virtual water film on the surface of the object, and fluid flow is incorporated into our anisotropic freezing solution to guide the growth direction of ice. As a result, the results of the glaze and directional freezing simulations are shown stably according to the flow direction of viscous water.

Ultrafast viscous water flow through nanostrand-channelled graphene oxide membranes

Pressure-driven ultrafiltration membranes are important in separation applications. Advanced filtration membranes with high permeance and enhanced rejection must be developed to meet rising worldwide demand. Here we report nanostrand-channelled graphene oxide ultrafiltration membranes with a network of nanochannels with a narrow size distribution (3-5 nm) and superior separation performance. This permeance offers a 10-fold enhancement without sacrificing the rejection rate compared with that of graphene oxide membranes, and is more than 100 times higher than that of commercial ultrafiltration membranes with similar rejection. The flow enhancement is attributed to the porous structure and significantly reduced channel length. An abnormal pressure-dependent separation behaviour is also reported, where the elastic deformation of nanochannels offers tunable permeation and rejection. The water flow through these hydrophilic graphene oxide nanochannels is identified as viscous. This nanostrand-channelling approach is also extendable to other laminate membranes, providing potential for accelerating separation and water-purification processes.

パルスドプラ法による嚥下機能検査法（第一報）

In this study we suggest that the velocity of water entering the cervical esophagus can be used as an index of pharyngeal swallowing function. In this article, the basic in vitro principles of water and viscous water flow velocity evaluation using ultrasonic methods are introduced. Water flow involving small gas bubbles passing through a silicon tube could be monitored in the B-mode images and the flow velocity could be measured by Doppler shift spectra produced by a medical ultrasound imaging (GE YOKOGAWA LOGIQ500 and linear convex probe 739L). By an in vitro experiment, we confirmed that the maximum water flow velocity (Vmax) obtained from Doppler shift spectra and actually measured water flow velocity showed a high correlation. The maximum velocity of viscous water flow measured from Doppler shift spectra and actually measured viscous water flow velocity also showed a high correlation.We measured Doppler spectra of water flow speed through the cervical esophagus of five subjects (two male, 41-50 y. o; three females, 28-42 y. o) without dysphasia 10 times and examined the coefficient of variation of Vmax. Values of the coefficient variation of Vmax were 3.4, 3.8, 8.8, 12.7, 15.5% (median 8.8%). It seemed that Vmax could be used as an index of the speed of water flow during swallowing. We suggest that the Doppler spectra of water flow speed through the cervical esophagus in swallowing analysis may be useful for assessing pharyngeal swallowing function, and that it may be useful in the diagnosis of pharyngeal swallowing disorders.