محمد واقفی

Marine Pipelines are among the most important offshore industry sections and many researchers are currently discussing the challenges that the structure is confronted with. Submarine pipes, when installed in the sea environment, are affected by a combination of steady currents and fluctuating and tidal currents. In this regard, one of the most standard and common methods is using a numerical model to simulate the passing current on pipes in a smaller scale. In the present study, a numerical simulator software of fluid flow called FLOW3D was utilized to analyze the fluid flow passing on the pipe’s surface. In this research, the model of fluid movement is numerically simulated along a marine pipeline under the influence of wave and current. The intended wave is a regular wave. The dominant equations are discretized using the finite volume method (FVM), and finally the equation system is solved. In the present study, turbulence model was investigated on the flow pattern around the pipeline and the results showed that the LES turbulence model offers more suitable results. It also studies the effect of Reynolds number, as well as the effect of period and wave height in the Flow Separation phenomenon around the pipeline under the influence of current and wave. Finally, the effect of Reynolds number and fitting distance in the Flow Separation phenomenon around the piggyback pipelines into the fitting arrangement were discussed. Moreover, the results showed that with the addition of a minor tube adhering to the main pipe, the symmetric shape of the Flow Separation at the bottom of the single pipe was eliminated and the length of the separation region would be reduced by 60 percent, as well as by increasing the installation distance to a certain limit, the length of the separation region increases for the main pipe and decreases for the sub pipe, but after passing the limit, the pattern of separation in the region of the wake flow becomes symmetrical and the effect of the tw