International Journal of Scientific Engineering and Technology (ISSN : 2277-1581) Volume No.3 Issue No.7, pp : 938-942 1 July 2014 IJSET@2014 Page 938 The Effect of length of a T Shape Spur Dike on Flow Patterns in 90 o Bend Channel with Support Structure 1 Mohamad Vaghefi, 2 Arash Ahmadi, 3 Behroz Faraji, 4 Mitra Javan, 5 Afshin Eghbalzadeh 1 Department of Civil Engineering, Persian Gulf University, Bushehr, Iran 2,3,4,5 Water Civil Engineering , Razi University, Kermanshah, Iran Vaghefi@pgu.ac.ir Abstract— Spur dike is kind of protection structure. In this paper, flow patterns around T shape spur dike and a support structure evaluated by variation of the length of T shape spur dike. After that, some of the hydraulic parameters such the power of secondary flow obtained from each simulation output. Keywords—T shape spur dike, support structure I. Introduction Spur dike is one of the common structures in hydraulic science that was protecting river morphology. Due to complex situation in bend channel especially around spur dike, a lots of investigation done to analyzed flow pattern in meandering rivers. Flow passed through meandering channels and spur dike is obviously a three-dimensional nature, so it is required a three dimensional hydrodynamic model to accurately simulate flow in meandering channels. Mesbahi (1992), Ghodsian and Mosavi (2004), Fazli et al (2007) and Forghani et al (2008) investigated on scour around spur dike in curved channel, experimentally. Dey and Barbhuiya (2006) studied the condition of flow patterns around vertical wall abutment. Vaghefi .et.al (2009 and 2012) used T-shaped spur dike located at section 75° in a bend worked on many parameters such as length and position of to a lesser extent to scour. Masjedi (2010) .et.al worked on T shape spur dike, which located in 45 and 60 degrees in outer bank of 180 o bend. The number of numerical studies regarding the flow pattern around the spur dike in a curved channel is not enough. Soliman (1998) determine morphology of Nile channel around groyne by two-dimensional method. Giri et.al in (2004) determine flow pattern around spur dike in meandering channel with numerical and experimental model. Olsen .et.al (2009) used a numerical to analyze flow pattern in meanderings channel, and main purpose of their study was about effects of the bed surface roughness on flow characteristics. Because of the a few studies, which related on support structure in bend channel, so in this paper the effect of support structure accompanied the variation of length of T shape spur dike on hydraulic parameters evaluated by numerical method? II. Material and Methodology According to the most of the numerical method, Flow-3D software has used momentum and continuity equation. Equation (1) shows continuity relation, which is relinquishing compressibility of fluid and Cartesian coordinate (x, y, z) directions. Momentum formulas show from equations 2 up to 4. ρ soR R ) z (wA z ) y (vA y x uA x t ρ F V (1) fx Gx x p z u z wA y u y vA x u x uA F V t u 1 1 (2) fy Gy y p z u z wA y u y vA x u x uA F V t v 1 1 (3) fz Gz z p z u z wA y u y vA x u x uA F V t w 1 1 (4) Here (u, v, w) are velocity components in (x, y, z) directions, and (Ax, Ay, Az) are fractional areas open to flow in the subscript directions, (Gx, Gy, Gz) are gravitational force in the subscript directions. F is part of fluid volume that is including to one and zero .one utilize when cell combine with fluid and zero use in vacant condition. By equation five, the amount of the F obtained which is a show as below. 0 . 0 ) ( ) ( ) ( 1 z FwA z u y FvA y x FuA x F V t F (5) In this model, from figure 1, four computational mesh blocks used to simulate all of the models. Two mesh block Fig. 1. view of computational mesh blocks Experimental data, which used in numerical model, carried out at the Hydraulic Laboratory of Tarbiat Modares University, Tehran [11]. The main channel consisted of 7.1m long upstream and 5.2m long downstream straight reaches. A 90° bend channel located between two straight reaches. The channel included rectangular cross section with 0.6m in width, 0.7m in height and 2.5m radius of bend to the centerline. The bed and sides of channel were made of glass that supported by a metal frame. Channel has 0.001 slope and ratio between radius and channel wide equaled to four. III. Results and Tables Accuracy of the numerical result is the most important parameter of each simulation Therefor the numerical and the experimental data for model with single T shape spur dike have compared in this paper. Figure 2 Mean velocity profiles at 50- degree cross section. It can take that the difference of the both