Backward erosion piping is an internal erosion mechanism, which if unmitigated may lead to the failure of a flood protection. The flow regime inside the pipe constitutes a knowledge gap in the field. It is expected that the change in regime is dependent on the boundary conditions and the geometry of the pipe. Whether laminar or turbulent flow is assumed in the pipe varies between the available modelling approaches. Experimental research at small scales indicates a dominant presence of laminar flow inside the pipe, but since turbulence is a scale dependent phenomenon, it is not clear if laminar flow is also dominating for larger scales. The present research aimed to investigate if the laminar flow assumption holds at larger scales than the ones tested in the lab. This work is done from a purely numerical stand point.