Seyed Ahmad Reza Saeidi Hosseini

Wastewaters are commonly discharged into the seas and oceans through multiport diffusers. Accurate prediction of the complex interactions of multiport diffusers with the receiving water bodies is significant for the optimal design of outfall systems and has yet to be fully illuminated. In the current study, the mixing and dilution characteristics of multiple inclined dense jets are studied using a three-dimensional numerical simulation. The Launder, Reece, and Rodi (LRR) turbulence model is employed to perform the simulations, and the predictions are compared against available experimental data. The results indicate that the LRR turbulence model is a promising tool for the study of inclined dense jets discharged from multiport diffusers, and it can provide more accurate predictions of the mixing behavior than standard and re-normalization group (RNG) k-ε turbulence models. The model is further employed to evaluate and compare the dispersion capabilities of multiport diffusers with uniform and non-uniform jet orientation to the horizontal, as a novel idea. The comparisons demonstrate the middle discharge may have a longer trajectory (7% and 5% increase in terminal rise height and impact point distance, respectively) and therefore a higher dilution rate (14% increase in impact dilution) when its adjacent jets are disposed with a different angle, compared to that of uniform discharges. The outcomes may be favorable for outfall systems applications involving dilution.

This study examines how various travel/built environmental and individual/household characteristics influence the walking durations of males and females in the city of Rasht, Iran, using data from the 2007 Rasht Household Travel Survey (RHTS). Accelerated hazard (AH) modelling, as a new approach in walking-related studies, was used to predict walking durations. The survival curve analysis showed that the ideal walking time was five minutes, but walking up to ten minutes was also acceptable. The AH models indicated that the walking duration of males and females varied under different conditions and contexts. For example, female workers were likely to walk longer trips relative to non-workers; however, this was the opposite among males. Household characteristics such as car ownership were found with greater negative effect on walking duration of males than females. Furthermore, zones with higher land use mix and higher connectivity led to shorter walking duration in both models.