Mohammad Vaghef - Assistant Professor, Department of Civil Engineering, Persian Gulf University, Iran
Hamed Dashtpeyma - Under graduate student, Department of Civil Engineering, Persian Gulf University, Iran
Arash Adib - Assistant Professor, Department of Civil Engineering, Shahid Chamran University, Ahvaz, Iran
Javad Roohian - Under graduate student, Department of Mechanic Engineering, Persian Gulf University, Iran

Bridges are one of the most important structures that their stability threatens by instability of their piers.The bridge collapse has been associated with scouring action of the flow around its piers. This complex phenomenon resulting from turbulent and vortex flow around piers. For proper design of piers, scouring effect must be mentioned for stability of them. and scouring cannot be investigated before studying of flow pattern . This paper is to report numerical analysis of flow pattern around square piers in rigid bed flowing water. Numerical analysis is based on software simulation with new generation of Ansys-CFX (12th Edition). But initial modeling will be performed with another software. Important variation and factor that this investigation based on them are Froude number of flow. At the end generated data from software simulation will be compared with laboratory researches. The locations of vortex systems and patterns of trailing wake-vortex systems will be found.

Bridge piers, Flow pattern, Vortex flow