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Showing 2 results for M. V. Samani
Volume 15, Issue 6 (11-2013)
Abstract
Advection-diffusion equation and its related analytical solutions have gained wide applications in different areas. Compared with numerical solutions, the analytical solutions benefit from some advantages. As such, many analytical solutions have been presented for the advection-diffusion equation. The difference between these solutions is mainly in the type of boundary conditions, e.g. time patterns of the sources. Almost all the existing analytical solutions to this equation involve simple boundary conditions. Most practical problems, however, involve complex boundary conditions where it is very difficult and sometimes impossible to find the corresponding analytical solutions. In this research, first, an analytical solution of advection-diffusion equation was initially derived for a point source with a linear pulse time pattern involving constant-parameters condition (constant velocity and diffusion coefficient). Hence, using the superposition principle, the derived solution can be extended for an arbitrary time pattern involving several point sources. The given analytical solution was verified using four hypothetical test problems for a stream. Three of these test problems have analytical solutions given by previous researchers while the last one involves a complicated case of several point sources, which can only be numerically solved. The results show that the proposed analytical solution can provide an accurate estimation of the concentration; hence it is suitable for other such applications, as verifying the transport codes. Moreover, it can be applied in applications that involve optimization process where estimation of the solution in a finite number of points (e.g. as an objective function) is required. The limitations of the proposed solution are that it is valid only for constant-parameters condition, and is not computationally efficient for problems involving either a high temporal or a high spatial resolution.
Volume 23, Issue 3 (5-2021)
Abstract
This experiment was conducted in order to determine the hydrodynamic performance of a Triangular Winged Bandal-Like (TWBL) structure, which is a combination of the Bandal-Like (BL) structure and Triangular Vane (TV). For the purposes of this study, the JFE ALEC magnetic velocity meter was used to measure the three components of flow velocity under non-submerged hydraulic conditions at a Froude number of 0.24. The three considered cases for this measurement were the non-structured case and the BL and TWBLs. The results showed that the flow deviation occurred through the impermeable upper part of both structures towards the middle of the channel. At downstream of both structures, bubbling flows were caused by the collision of upward flows with the near-surface flow, causing disturbances in the latter. Both the BL and the TWBL structure reduced the secondary flow strength along the bend within the structure range. Compared to the BL structure, the TWBL structure reduced the secondary flow strength by about 20%, which indicates the weaker inclination of the secondary flow toward the outer bank in the TWBL structure. The relative maximum shear stress in the TWBL structure is on average 17% lower than that of the BL structure.