| Analysis of flow around a circular cylinder has been is one of many theories,experimental study and numerical simulation of the object, but because of the complexity of cylindrical three- dimensional flow around so far on the flow of physical understanding of the nature of the phenomenon is still incomplete, particularly for flow around cylindrical flow around cylindrical Pier scour and State relations, has not yet formed system theory research. This article uses flow numerical simulation of 3D fluid dynamics software, study on flow field characteristics of flow around a cylindrical Pier and Pier scour characteristics,exploring the relationship between flow and scour around a cylinder, with a view to provide theoretical basis for the study on flow around cylindrical Pier and scouring and new research ideas.The author used Flow-3D to study the simulation of flow around a single cylindrical pier and variation of scour, obtained flow pattern and riverbed scour features around cylindrical pier. Results show that, ①cylindrical Pier second dimension flow field distribution features for near on both sides sink edge wall of effect, flow velocity reduce,Pier before because pier on flow of barrier role makes flow velocity reduces close to 0, Pier after, as process of increased, flow field became ride comfort and stability; ② increase the initial velocity range around the flow near the bridge pier concentrated flow around before the pier, the pier after the wake influence expanded; ③the initial velocity of 37 cm/s,maximum of two-dimensional planar velocity of 42.3cm/s, the other two under the initial velocity of two-dimensional velocity distribution also has the same rules, including the maximum velocity of 34.4cm/s, respectively 22.2cm/s, the three dimensional velocity components in the longitudinal velocity is one of the biggest, the other two velocity component in the direction of small but mainly affect the migration direction of the flow velocity.This paper simulated the flow around pier under different piers arrangement, and analyzed the flow pattern, velocity distribution and scouring terrain. The results showed:①when the piers were linear and uniform arranged to 2 rows of 10 and its axis had different angles with flow direction, it was bound to affect each other mutually. The results showed that the pier near upstream affected the pier’s flow structure that near the downstream. The maximum scour depth position located in the front row Pier 2when arranged 60°, the scour depth was 7.66 cm when t=4s, and the scour depth was 11.27 cm when t=6s. Scour depth increases with the increase of time until finally reached sedimentation equilibrium. ②when the piers were arranged at 60°, the 1st~5thcylinders’ flow rate have a significant symmetry,and scouring range is smallest in front of the middle 3rd pier. However, when the piers were arranged at 30° or 60°, flow rate value before the 1st pier was significantly higher than the other 4 piers, and it trend to gradually decreasing. It showed that the piers’ oblique dispersion reduced its resistance to water when diagonal layout. The row of piers near the left bank were more serious scoured when arranged at 0 °, the scour is more serious than others on the 1st and the 5th pier when arranged at30 °, and the scouring range is greater on the 1st and the 5th pier when arranged at60 °. In general, through the experimental study, this paper simulated the flow around of piers by using Flow 3D software, compared the results with the actual test, combined two kinds of numerical methods of simulation and actual experimental research successfully, and finally analysis the water’s distribution characteristics and the scour deformation of riverbed. The results can also provide a reference for future similar research. |
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