Search

In this research, complementary numerical and experimental physical models were conducted to investigate flow parameters around an isolated permeable spur dike using ANSYS FLUENT ver. 16.1 software. The volume of fluid method VOF with the help of CFD technique and the κ − ε turbulence model was used to simulate the complex free-surface flow by applying a geometric reconstruction scheme. Two different mediums with different porosities were used, namely, gravel and glass beads. It was found that, for low flow rate values, there are no significant changes in the water profiles in both longitudinal and lateral directions for both media. Although for high flow rate values, the differences tend to be clearer. Results showed that there is a slight effect of the medium's properties if the dike width is less than 1/3 of width of the channel, in particular with low flow rate values. Good agreement was observed between the computational and the measured results for the water surface profiles. Also, there is an exact match between the lateral velocity distribution of gravels and glass beads. Downstream the dike, the lateral velocity profiles exhibit an S shape curve due to high velocity in the free flow and small flow velocity behind the porous dike. The results show good agreement between the CFD results and the experimental observations of the water surface profiles and velocity distribution according to the statistical analysis using some standard indexes error. [ABSTRACT FROM AUTHOR]

Efforts were made in this search to design a physical and computer model using the CFD techniques to simulate the problem of transporting pollutants through a porous media in unsteady state case. A physical model was built to measure the transmission of a copper nitrate pollutant at an initial concentration of 25 mg/l in a medium consists of (sand + gravel) and study the movement of the pollutant through. Then the results of the pollutant transport through used in the physical model were entered as entry data to the CFD simulated model using COMSOL 5.4. Software. The results of the CFD simulated model showed that the change in the inlet velocity to more than 20% of the initial velocity increases the pollutant concentration and reduces the time wanted to reach the highest value of the pollutant, while reducing the inlet velocity to less than 20% of the initial velocity, cause to decrease the concentration and increase the time to reach the highest pollutant value. When changing the porosity by (30%, -15%) of the initial porosity, it was noticed that increasing the porosity value reduces the pollutant concentration and increases the time required to reach the highest value of the pollutant. while when the porosity decreases to 15% of the initial porosity, the concentration increases the time decreases to reach the highest value of the pollutant at all control points. The adsorption factor has a noticeable effect on the emergence of the pollutant, while the temperature change was almost imperceptible for all degrees. However, the results of laboratory work were compared with the results of the CFD simulated model, which showed a good match between them. [ABSTRACT FROM AUTHOR]

Seepage is a flow that happens through / under hydraulic structures or through the porous media such as in the case of earth dams from upstream to downstream due to difference in the hydraulic head. Study of seepage flow is important for hydraulic engineering. Before the structures being built, the behaviors of the seepage flows must be predicted because the seepage flow causes harmful to hydraulic structures. In this paper, a homogenous earth dam with sand material is proposed and constructed with horizontal bed filter at the Toe of the dam is taken as a case study. Through this Comsol is used to interpret the seepage of flow and contaminants transportation through the dam. The general objective of this paper is thus to present a prediction model aimed at quantifying a selected concentration of contaminants in the reservoir, and then predicted in the body of the dam, and at the exit from the dam. Computation Fluid Dynamics (CFD) Module (Comsol version 4.2) with its sub-programs named (Free and Porous Media Flow and Species Transport through Porous Media) was used in the analysis and study the seepage flow and of the contaminants transportation. This software is based on the finite element techniques that were used for solving the governing equations of flow and transportation of contaminant through porous media. Also, it was used to determine the phreatic line, amount of seepage within the dam, the pressure head, the total head, and the amount of contaminates transported through the dam body. From the comsol software, it is deduced that when the water level is at the maximum height (20m), it needs 12 days and (18) hr, at normal height (15m) it needs 29 days, while at a minimum height (8 m) it needs 81 days to reach the drain zone. [ABSTRACT FROM AUTHOR]