In this work, periodic vortex shedding at both sides of a circular cylinder is aimed to be suppressed using a concentrically located perforated cylinder under laminar flow conditions at Re=200. A code is developed in Comsol Multiphysics, 5.3a and validated using the outcomes of Ansys, Fluent and previous studies in the open literature, which exhibit a good agreement. The porosity, β, and is varied within 0.5≤β≤0.9, and the gap ratio, D/d is varied within 1.5≤D/d≤3.5 to determine the optimum parameters. The results of the present numerical investigation are evaluated using instantaneous and time-averaged vorticity, streamwise and transverse components of the velocity and pressure. The drag, C_D and lift, C_L coefficients are calculated. Strouhal number, St from the pointwise spectral analysis of the streamwise velocity component is plotted for various cases. It is observed that porosity βhas a dominant effect rather than the gap ratio on the flow past a solid cylinder. The low-velocity and low-pressure regions are getting large in the transverse direction as the porosity increases. The separated layers from solid and perforated cylinders merge for low gap ratios. However, individual movement of these layers is evident for larger gap ratios with low porosity,β values. A perfect suppression of the periodicity of vortex shedding is obtained for the cases of D/d=3.5 with β=0.5,0.6 and D/d=3 with β=0.5.

Induced-charge electro-osmosis around multiple gold-coated stainless steel rods under various AC electric fields is investigated using the techniques of microparticle image velocimetry and numerical simulation. In this study, the results of interactions between induced electric double layers of two identical conductive cylinders on surrounding fluid are presented. The induced-charge electro-osmosis flow around multiple rods in touch and with one cylinder diameter gap reveals quadrupolar flow structures with four vortices. The induced-charge electro-osmotic flow structure and velocity magnitude also depend on the cylinder geometry and orientation. It is seen that four small vortices develop in the close region of cylinder surface for multiple rods with gap, while the other four large vortices are surrounding them. The distributions of vorticity patterns also strongly depend on cylinder orientation in the close region of cylinder surface.

This paper presents the findings of laboratory model testing of arched bridge constrictions in a rectangular open-channel flume whose bed slope was fixed at zero. Four different types of arched bridge models, namely single-opening semi-circular arch, multiple-opening semi-circular arch, single-opening elliptic arch, and multiple-opening elliptic arch, were used in the testing program. The normal crossing (φ  = 0) and five different skew angles (φ  = 10°, 20°, 30°, 40°, and 50°) were tested for each type of arched bridge model. Recently, a major coverage of backwater field data obtained from the medieval arched bridge constrictions was published by the Hydraulic Research Wallingford in the UK (Brown, P.M., 1985. Hydraulics of bridge waterways: Interium report. Wallingford, UK: Hydraulic Research Wallingford, Report SR 60; Brown, P.M., 1987. Afflux at arch bridges: second interium report. Wallingford, UK: Hydraulic Research Wallingford, Report SR 115; Brown, P.M., 1988. Afflux at arch bridges. Wallingford, UK: Hydraulic Research Wallingford, Report SR 182). These data were also used in the analysis. The main aim of this study is to develop a suitable model for estimating backwater through arched bridge constrictions with normal and skewed crossings using both experimental and field data. Therefore, different artificial intelligence approaches, namely multi-layer perceptron (MLP), radial basis neural network (RBNN), generalized regression neural network (GRNN), and multi-linear and multi-nonlinear regression models, MLR and MNLR, respectively were used. The comparison between these developed models and one of the most commonly used traditional methods (Biery, P.F. and Delleur, J.W., 1962 Biery, P. F. and Delleur, J. W. 1962. Hydraulics of single span arch bridge constrictions. ASCE Journal of the Hydraulics Division, 88: 75–108. [Google Scholar] . Hydraulics of single span arch bridge constrictions. ASCE Journal of the Hydraulics Division, 88, 75–108) has been made. The test results showed that the MLP model gave highly accurate results than those of Biery and Delleur, MLR, MNLR, and GRNN and gave similar results with the RBNN model when applied to both field and experimental data.