A model was developed for the analysis of steady and unsteady bubble generation frequencies in a microfluidic flow-focusing device. In both cases, the generation frequency depends on the downstream influence of bubbles created by the flow-focusing device, which provides a source of feedback. For steady-state generation of bubbles, this feedback explains the relationships among frequency, gas pr...

for preventing groundwater and soil from heavy metal contamination and/or to decrease contamination, and to clean up the former disposal sites from these metals, one must be beforehand able to predict the movement of these pollutants in soils. in this research in order to describe cadmium [cd (ii)] transport in soils, we incorporated an equilibrium-kinetic two-site model into the convection-dis...

Negative surges are caused by a sudden change in flow resulting from a decrease in water depth. New experiments were conducted in a horizontal channel (L = 12 m, W = 0.5 m) to record the unsteady water depth and turbulence in negative surges. The data were collected using video imagery, acoustic displacement meters and acoustic Doppler velocimetry (ADV). The experimental setup was designed to r...

In an open channel, a sudden drop in free-surface elevation is associated with the development of a negative wave. While some simple analytical solution is widely described in textbooks, little research was conducted to date on the unsteady turbulence properties beneath negative waves. A series of new physical experiments were conducted in a rectangular channel. The unsteady free-surface profil...

Direct pore scale simulations of two-fluid flow on digital rock images provide a promising tool to understand the role surface wetting phenomena and transport in geologic reservoirs. We present computational protocols that mimic conventional special core analysis laboratory (SCAL) experiments, which are implemented within open source LBPM software package. Protocols described simulate unsteady ...

the system dynamics technique is an object-oriented approach that studies and manages complex feedback systems. its merits include the friendly and easy development and improvement of a model. it is also used as a decision tool for engineering problems. in this paper, the system dynamics technique was used to simulate the performance of a subsurface drainage system in an unsteady state. the mod...