KINETICS OF ELECTRORHEOLOGICAL FLUID SPREADING OVER A HORIZONTAL SURFACE

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2711-2717
Author(s):  
V. I. BAYKOV ◽  
E. V. KOROBKO

A Physical and Mathematical model of the process of fluid drop spreading is suggested which quantitatively describes all the stages of spreading kinetics on the basic of a unified approach. It has been established that gravitational forces exert a pronounced influence on the process of fluid drop spreading over a horizontal solid surface.

2020 ◽  
Vol 146 ◽  
pp. 03004
Author(s):  
Douglas Ruth

The most influential parameter on the behavior of two-component flow in porous media is “wettability”. When wettability is being characterized, the most frequently used parameter is the “contact angle”. When a fluid-drop is placed on a solid surface, in the presence of a second, surrounding fluid, the fluid-fluid surface contacts the solid-surface at an angle that is typically measured through the fluid-drop. If this angle is less than 90°, the fluid in the drop is said to “wet” the surface. If this angle is greater than 90°, the surrounding fluid is said to “wet” the surface. This definition is universally accepted and appears to be scientifically justifiable, at least for a static situation where the solid surface is horizontal. Recently, this concept has been extended to characterize wettability in non-static situations using high-resolution, two-dimensional digital images of multi-component systems. Using simple thought experiments and published experimental results, many of them decades old, it will be demonstrated that contact angles are not primary parameters – their values depend on many other parameters. Using these arguments, it will be demonstrated that contact angles are not the cause of wettability behavior but the effect of wettability behavior and other parameters. The result of this is that the contact angle cannot be used as a primary indicator of wettability except in very restricted situations. Furthermore, it will be demonstrated that even for the simple case of a capillary interface in a vertical tube, attempting to use simply a two-dimensional image to determine the contact angle can result in a wide range of measured values. This observation is consistent with some published experimental results. It follows that contact angles measured in two-dimensions cannot be trusted to provide accurate values and these values should not be used to characterize the wettability of the system.


1998 ◽  
Vol 208 (1) ◽  
pp. 226-240 ◽  
Author(s):  
Chun Yang ◽  
Tadeusz Dabros ◽  
Dongqing Li ◽  
Jan Czarnecki ◽  
Jacob H. Masliyah

2003 ◽  
Vol 67A (2) ◽  
pp. 582-590 ◽  
Author(s):  
Sergei L. Vasin ◽  
Igor A. Titushkin ◽  
Viktor I. Sevastianov

Author(s):  
Л.Ф. Сафиуллина

В статье рассмотрен вопрос идентифицируемости математической модели кинетики химической реакции. В процессе решения обратной задачи по оценке параметров модели, характеризующих процесс, нередко возникает вопрос неединственности решения. На примере конкретной реакции продемонстрирована необходимость проводить анализ идентифицируемости модели перед проведением численных расчетов по определению параметров модели химической реакции. The identifiability of the mathematical model of the kinetics of a chemical reaction is investigated in the article. In the process of solving the inverse problem of estimating the parameters of the model, the question arises of the non-uniqueness of the solution. On the example of a specific reaction, the need to analyze the identifiability of the model before carrying out numerical calculations to determine the parameters of the reaction model was demonstrated.


2018 ◽  
Vol 78 (9) ◽  
pp. 1916-1924 ◽  
Author(s):  
Lucie Pokorna-Krayzelova ◽  
Dana Vejmelková ◽  
Lara Selan ◽  
Pavel Jenicek ◽  
Eveline I. P. Volcke ◽  
...  

Abstract Hydrogen sulfide is a toxic and usually undesirable by-product of the anaerobic treatment of sulfate-containing wastewater. It can be removed through microaeration, a simple and cost-effective method involving the application of oxygen-limiting conditions (i.e., dissolved oxygen below 0.1 mg L−1). However, the exact transformation pathways of sulfide under microaerobic conditions are still unclear. In this paper, batch experiments were performed to study biochemical and chemical sulfide oxidation under microaerobic conditions. The biochemical experiments were conducted using a strain of Sulfuricurvum kujiense. Under microaerobic conditions, the biochemical sulfide oxidation rate (in mg S L−1 d−1) was approximately 2.5 times faster than the chemical sulfide oxidation rate. Elemental sulfur was the major end-product of both biochemical and chemical sulfide oxidation. During biochemical sulfide oxidation elemental sulfur was in the form of white flakes, while during chemical sulfide oxidation elemental sulfur created a white suspension. Moreover, a mathematical model describing biochemical and chemical sulfide oxidation was developed and calibrated by the experimental results.


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