Numerical investigating of the effect of lateral channel junction position on flow pattern at river bend

Rivers have direct pathway rarely and run in a sinus curve pattern usually. Joining lateral channel to main channel at a bend location changes the conventional flow pattern at river bend completely. Recent flow pattern not only is affected by centrifugal force and stream and spin wise pressure gradient but also by momentum of lateral channel flow. Exact recognizing of this phenomenon needs extended studies. Therefore in this study using SSIIM1 model the effect of three position of straight lateral channel that is connected to a U bend at 45, 90 and 135 degree from the start of bend with a 90 degree confluence angle on flow velocity, variation of water surface elevation, shear stress distribution and helical flow strength was considered. The result indicated by increasing the junction position from 45 to 135 degree of the bend start, stream wise flow velocity near the outer wall of bend increases maximum %56 while near the inner wall of bend decreases %8. Also maximum difference between the upstream and downstream flow depth around confluence area at 45 degree position was showed that was equal to %6.15 of tailwater depth. For position of 135 degree of the bend start this difference was about %5.4 of tailwater depth. Additionally the result indicated shear stress at confluence area increases %8 when the position of junction angle change from 45 to 135 from start of bend.