Experimental and Numerical Investigation of Self-Burial Mechanism of Pipeline with Spoiler under Steady Flow Conditions

Abstract

Herein, hydraulic model experiments and numerical simulations were performed to understand the self-burial mechanism of subsea pipelines with spoilers under steady flow conditions. First, scour characteristics and self-burial functions according to the spoiler length-to-pipe diameter ratio (S/D) were investigated through hydraulic experiments. Further, the Navier-Stokes solver was verified. The experimental values of the velocity at the bottom of the pipeline with a spoiler and the pressure on the sand foundation where the pipeline rested were represented with the degree of conformity. Scour characteristics of a sand foundation were investigated from the numerical analysis results of the velocity and vorticity surrounding the pipelines with spoilers. The compilation of results from the hydraulic experiment and numerical analysis showed that the projected area increased when a spoiler was attached to the subsea pipes. This consequently increased the velocity of fluid leaving the top and bottom of the pipe, and high vorticity was formed within and above the sand foundation. This aggravated scouring at the pipe base and increased the top and bottom asymmetry of the dynamic pressure field, which developed a downward force on the pipeline. These two primary effects acting simultaneously under steady flow conditions explained the self-burial of pipelines with a spoiler attachment.

Numerical Study of Local Scour around a Submarine Pipeline with a Spoiler Using a Symmetry Boundary Condition

“…The corresponding results shown in Figure 9 confirm again that a spoiler with a larger length leads to a deeper scour depth beneath the pipeline. This observation is consistent with the results given by Lee et al [18], who found that a longer spoiler leads to a deeper scour depth with L/D = 0, 0.3 and 0.5, respectively. Based on the present numerical results, a quadratic polynomial function relationship is found between the scour depth and the spoiler length as follows: Figure 8 shows the numerical results of the local scour profile around the pipeline without and with a spoiler at t = 3000 s. It can be seen that although the scour profile does not change much for a pipeline with and without a spoiler, the scour range and the scour depth increase with the increase of the spoiler length.…”

“…The corresponding results shown in Figure 9 confirm again that a spoiler with a larger length leads to a deeper scour depth beneath the pipeline. This observation is consistent with the results given by Lee et al [18], who found that a longer spoiler leads to a deeper scour depth with L/D = 0, 0.3 and 0.5, respectively. Based on the present numerical results, a quadratic polynomial function relationship is found between the scour depth and the spoiler length as follows:…”

“…To identify the detailed relationship, Figure 9 shows the dependen of the non-dimensional scour depth (S/D) on the non-dimensional spoiler length (L/ The corresponding results shown in Figure 9 confirm again that a spoiler with a lar length leads to a deeper scour depth beneath the pipeline. This observation is consist with the results given by Lee et al [18], who found that a longer spoiler leads to a dee scour depth with L/D = 0, 0. From the above discussion, it confirms that the spoiler length has a significant effect on the scour depth.…”

“…The experimental results revealed that the scour depth beneath a submarine pipeline is dependent on the spoiler length. Both experimental and numerical studies were carried out to investigate the self-burial mechanism of a pipeline with a spoiler in a steady current in [18]. It is found that this is mainly due to the fact that the projected area is increased by the spoiler.…”

Effects of Wave Breaking over Submerged Horizontal Plate on Solitary Wave Control

“…그 밖에 경계요소법 (Cho et al, 2013)과 유한차분법 (Kweon et al, 2014) 을 이용하여 SHP의 수리성능을 분석하기도 하였다. (Hayatdavoodi et al, 2017;You et al, 2019;Xu et al, 2019 (Lee et al, 2016b;Lee et al, 2018;Lee et al, 2019b;Lee et al, 2019c) 에서 여러 검증을 통해 확인된 바 있다.…”