Bridges over rivers are often supported by long vertical structures called piers. The flow of water around those piers can erode a riverbed, a process called scouring, and one of the leading causes of a bridge's failure. To understand better how water behaves around shapes of bridge piers, this study used advanced computer simulations. The analysis was carried out by a software package called ANSYS Fluent, to simulate water flow three dimensionally. The software was tested with five different pier shapes, both with single and twin pier configurations. In twin pier configurations, three positions were taken into account: one behind another, side by side, and angled to flow. Those configurations generate more complex water flow compared to a single pier. The study took into account how different speeds and shapes of water affect flow characteristics such as velocity, pressure, turbulence, and forces against a riverbed. It concluded that pier shape, position, and shape affect water motion significantly, as they dictate where erosion tends to be more likely. Those results can help engineers from countries like Bangladesh to construct stronger and longer-lasting bridges, especially as rising transportation demand triggers more infrastructure construction.