Effect of Mesh Number on Accuracy of Semi Submersible Motion Prediction

Abyn, Hassan; Maimun, Adi; Islam, Mohammad Rafiqul; Magee, Allan; Jaswar, Jaswar; Bodaghi, Behnam; Pauzi, Mohamad; Siow, C. L.

doi:10.11113/jt.v66.2486

Cited by 6 publications

(6 citation statements)

References 6 publications

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“…The number of panels is 824 for each structure. [18] showed that by increasing mesh numbers almost two times, calculation time increases about five times and by increasing panel number in four times it reaches up to twenty times.…”

Section: Resultsmentioning

confidence: 99%

Experimental Study of Motions of Two Floating Offshore Structures in Waves

Abyn

Islam

Maimun³

et al. 2016

brod

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SummaryDrilling is carried out in deeper to deeper waters around the globe to meet growing demands for oil and natural gas, and a number of multi body structures are deployed in various oil fields in the world. Investigation of hydrodynamic interaction of offshore structures is therefore worthwhile. Hydrodynamic interaction between floating offshore structures affects motion and relative motion especially during loading and offloading operations. Hydrodynamic interactions may lead to large motions of floating bodies that would cause damage to moorings and offloading systems and may collide with each other. This research work discusses experimental results of hydrodynamic interaction in surge, heave and pitch motion, relative motion and relative distance between a Tension Leg Platform (TLP) and semi-submersible (Tender Assisted Drilling) in regular waves. The experiment is conducted without tendon because of the depth limitation of the Towing Tank. However, in order to consider the contribution of mooring in linear direction, appropriate stiffness of horizontal springs have been used. The experiment was conducted for a full scale wave height of 3.77 m to 12.49 m for a separation distance of 21.7 m.From the analyses of the experimental and numerical results, it can be concluded that nonlinearity of the wave has an important effect on increasing the motion especially in the natural frequency region. Finally, a number of recommendations have been made for further study.

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Section: Resultsmentioning

confidence: 99%

Experimental Study of Motions of Two Floating Offshore Structures in Waves

Abyn

Islam

Maimun³

et al. 2016

brod

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“…Increasing mesh number does not affect the accuracy of the calculated results except in the range of natural frequencies. Abyn et al (2014) [18] showed that by increasing mesh numbers almost two times, calculation time increases about five times and by increasing panel number in four times it reaches up to twenty times. Fig.…”

Section: Resultsmentioning

confidence: 99%

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2016

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Drilling is carried out in deeper to deeper waters around the globe to meet growing demands for oil and natural gas, and a number of multi body structures are deployed in various oil fields in the world. Investigation of hydrodynamic interaction of offshore structures is therefore worthwhile. Hydrodynamic interaction between floating offshore structures affects motion and relative motion especially during loading and offloading operations. Hydrodynamic interactions may lead to large motions of floating bodies that would cause damage to moorings and offloading systems and may collide with each other. This research work discusses experimental results of hydrodynamic interaction in surge, heave and pitch motion, relative motion and relative distance between a Tension Leg Platform (TLP) and semi-submersible (Tender Assisted Drilling) in regular waves. The experiment is conducted without tendon because of the depth limitation of the Towing Tank. However, in order to consider the contribution of mooring in linear direction, appropriate stiffness of horizontal springs have been used. The experiment was conducted for a full scale wave height of 3.77 m to 12.49 m for a separation distance of 21.7 m. From the analyses of the experimental and numerical results, it can be concluded that nonlinearity of the wave has an important effect on increasing the motion especially in the natural frequency region. Finally, a number of recommendations have been made for further study.

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“…A model test related to interaction between semi-submersible and TLP was carried out by Hassan Abyn et al [12]. In continuing Hassan Abyn et al also tried to simulate the motion of a semi-submersible by using HydroSTAR and then analysed the effect of meshing number to the accuracy of execution result and execution time [13]. Besides, C. L. Siow et al also make a comparison on the motion of a semisubmersible when it alone to interaction condition by using previous experimental result [14].…”

Section: 20 Literature Reviewsmentioning

confidence: 99%

“…Where the M is structure mass, 𝐴 33 is heave added mass, 𝐵 33 is linear damping from diffraction potential theory, 𝑏 𝑣 is the viscous damping defined at Equation (13), c is the heave restoring force, and F is the wave force contributed to heave motion.…”

Section: Viscous Dampingmentioning

confidence: 99%

“…Besides that, the structure heave decay experiment data, such as damping ratio, natural frequency is needed to provide to the programming manually. Based on the data, heave viscous damping can be obtained by using the Equation (13). In this numerical approach, the heave viscous damping is treated as an independent term which is calculated separately from the diffraction potential theory.…”

Section: Programming Flow Chartmentioning

confidence: 99%

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Prediction of Semi-Submersible’s Motion Response by Using Diffraction Potential Theory and Heave Viscous Damping Correction

Siow

Koto²,

Abby

et al. 2014

Jurnal Teknologi

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This paper proposes a three dimensional diffraction potential theory with heave viscous damping correction to predict motion response of multiple hulls semi-submersible structure. The heave viscous damping correction was applied in this paper to avoid the execution return an infinity value for heave motion when the heave motion is dominated by damping term. On previous stage, this method was shown it capability to apply on single hull structure. However, some modification is required to able the single hull diffraction potential theory applied to multiple hull structure. Upon this stage, the modification was made into the meshing system in purposes to able the numerical coding calculate the response of semi-submersible structure. This paper also presented the comparison between the result calculate by diffraction potential theory, commercial software-Hydrostar and experiment result in the selected semi-submersible model. In the comparison, it is obtained that the tendency between the numerical results and the experimental result is agreed between each other.

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Effect of Mesh Number on Accuracy of Semi Submersible Motion Prediction

Cited by 6 publications

References 6 publications

Experimental Study of Motions of Two Floating Offshore Structures in Waves

Experimental Study of Motions of Two Floating Offshore Structures in Waves

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Prediction of Semi-Submersible’s Motion Response by Using Diffraction Potential Theory and Heave Viscous Damping Correction

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