Muse Tofa | STP AMPTA Yogyakarta (original) (raw)
Address: Yogyakarta, Indonesia
less
Uploads
Papers by Muse Tofa
Volume 2: CFD and VIV, 2014
ABSTRACT
Jurnal Teknologi, 2014
Floating structures play an important role for exploring the oil and gas from the sea. In loading... more Floating structures play an important role for exploring the oil and gas from the sea. In loading and offloading, motion responses of offshore floating structures are affected through hydrodynamic interaction. Large motions between floating bodies would cause the damage of moorings, offloading system and may colloid to each other. This research studies on hydrodynamic interaction between Tension Leg Platform (TLP) and Semi-Submersible (Tender Assisted Drilling (TAD)) in regular and irregular waves with scenario as follows: fixed TLP and 6-DOF floating semi-submersible and 6-DOF both TLP and semi-submersible. Under these conditions, hydrodynamics coefficients, mooring and connectors forces, motions and relative motions of TLP and Semi-Submersible will be simulated numerically by using 3D source distribution method. As the scope is big, this paper only presents model experiment of floating TLP and semi-submersible in the regular wave. The experiment is carried out in the UTM Towing Tank.
Jurnal Teknologi, 2014
Study of vibrations due to vortex shedding (VIV) in the wake of a cylinder that is exposed to cur... more Study of vibrations due to vortex shedding (VIV) in the wake of a cylinder that is exposed to current or oscillatory flow is very important, especially for marine risers which are used to extract oil and gas from the sea bed. The phenomenon of vortex induced vibration (VIV) has been one of the major concerns for hydrodynamic researchers due to its potential ability to cause severe fatigue damage. The hydrodynamics of VIV is very complex and still not fully understood. In this paper, some results (amplitude over diameter, lift and drag coefficients) of high Reynolds VIV experiments that are performed in UTM towing tank with an in-house test set-up are presented. A circular cylinder of 114 mm in diameter and 3 min length was towed at constant speed through the basin at Reynolds numbers up to 1.1x10 5 . Model tests with a stationary cylinder and tests with a freely vibrating cylinder were carried out to investigate the influence of VIV on drag coefficient. Later these results are compared with results obtained through 3D numerical simulation, LES is used to solve turbulence flow. It was found that CFD results showed similar trends with experimental results. Results of this paper can be very important to design riser system and future endeavor to perform similar kind of experiments. Successful numerical study of the VIV can also be fruitful for designing efficient VIV suppression devices.
Jurnal Teknologi, 2014
The height static stability of a wing can be a main concern for conceptual design of wing-in-grou... more The height static stability of a wing can be a main concern for conceptual design of wing-in-ground effect (WIG) crafts. In this research, the stability of a rectangular and compound wing was computationally predicted in ground effect. A realizable k-ε turbulent model was used for simulation the flow filed over the wing surfaces. First, the drag coefficient and lift to drag ratio of numerical simulation were validated by experimental data of the rectangular wing. Next, the stability of the compound wing respect to different ground clearances will be determined and compared with rectangular wing. This study illustrated a deep understanding of static stability of present compound wing in ground effect, which eventually can be a guideline for researchers and designers of WIG craft.
Volume 2: CFD and VIV, 2014
ABSTRACT
Jurnal Teknologi, 2014
Floating structures play an important role for exploring the oil and gas from the sea. In loading... more Floating structures play an important role for exploring the oil and gas from the sea. In loading and offloading, motion responses of offshore floating structures are affected through hydrodynamic interaction. Large motions between floating bodies would cause the damage of moorings, offloading system and may colloid to each other. This research studies on hydrodynamic interaction between Tension Leg Platform (TLP) and Semi-Submersible (Tender Assisted Drilling (TAD)) in regular and irregular waves with scenario as follows: fixed TLP and 6-DOF floating semi-submersible and 6-DOF both TLP and semi-submersible. Under these conditions, hydrodynamics coefficients, mooring and connectors forces, motions and relative motions of TLP and Semi-Submersible will be simulated numerically by using 3D source distribution method. As the scope is big, this paper only presents model experiment of floating TLP and semi-submersible in the regular wave. The experiment is carried out in the UTM Towing Tank.
Jurnal Teknologi, 2014
Study of vibrations due to vortex shedding (VIV) in the wake of a cylinder that is exposed to cur... more Study of vibrations due to vortex shedding (VIV) in the wake of a cylinder that is exposed to current or oscillatory flow is very important, especially for marine risers which are used to extract oil and gas from the sea bed. The phenomenon of vortex induced vibration (VIV) has been one of the major concerns for hydrodynamic researchers due to its potential ability to cause severe fatigue damage. The hydrodynamics of VIV is very complex and still not fully understood. In this paper, some results (amplitude over diameter, lift and drag coefficients) of high Reynolds VIV experiments that are performed in UTM towing tank with an in-house test set-up are presented. A circular cylinder of 114 mm in diameter and 3 min length was towed at constant speed through the basin at Reynolds numbers up to 1.1x10 5 . Model tests with a stationary cylinder and tests with a freely vibrating cylinder were carried out to investigate the influence of VIV on drag coefficient. Later these results are compared with results obtained through 3D numerical simulation, LES is used to solve turbulence flow. It was found that CFD results showed similar trends with experimental results. Results of this paper can be very important to design riser system and future endeavor to perform similar kind of experiments. Successful numerical study of the VIV can also be fruitful for designing efficient VIV suppression devices.
Jurnal Teknologi, 2014
The height static stability of a wing can be a main concern for conceptual design of wing-in-grou... more The height static stability of a wing can be a main concern for conceptual design of wing-in-ground effect (WIG) crafts. In this research, the stability of a rectangular and compound wing was computationally predicted in ground effect. A realizable k-ε turbulent model was used for simulation the flow filed over the wing surfaces. First, the drag coefficient and lift to drag ratio of numerical simulation were validated by experimental data of the rectangular wing. Next, the stability of the compound wing respect to different ground clearances will be determined and compared with rectangular wing. This study illustrated a deep understanding of static stability of present compound wing in ground effect, which eventually can be a guideline for researchers and designers of WIG craft.