CFD Simulation offshore

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Added mass

The entrained water or added mass moving together with a submerged artefact is one of the critical calculations to be done when analyzing offshore lifting and installation operations. We have developed our own validated methodology for accurately calculating the added mass on any geometry, it doesn’t matter how complex it is. This calculation is done with the CFD code for every direction and taking into account aspects like distance to sea bottom or other objects. The results allow you to reduce the uncertainty compared with traditional methods like the added mass coefficients on DNV-RP-C205 or similar guides. The advantages for the operator results on a more accurate operational window for lifting operations

Slamming

Slamming computations can be done on any floating artefact and under any sea state. This type of analysis is important to determine the dynamic loads due to sea waves impact on the ship hull. We have helped solve slamming impact problems on ships, improving hull geometry reducing impacts derived from slamming pressures significantly by defining new hull geometry.

Green water

Water on deck can damage ship’s equipment; this type of analysis is done normally for offshore vessels like FPSO or more conventional ships on heavy weather. This phenomenon can occur on every ship direction but is normally analyzed on the ship’s bow. For carrying out this type os study, we model the ship’s superstructure together with its details and the ship hull with its associated mass and inertia properties. For each irregular or regular sea state we reproduce the ship motions with a typical seakeeping analysis but focusing on the water getting onboard. We can calculate the amount of water embarked as a function of time. Our tools and experience allow us to do these studies very quickly and obtaining very useful information for designing better and safer ships.

Vortex induced motion/vibration

Analysis of the vortex induced vibrations and motions are important in order to evaluate the fluctuating forces on submerged structures derived from these instabilities. This study can be done also coupling the fluid dynamics with a coupled finite element computations for the body, in such a way that the stress and vibration on the structure is evaluated. Based on a solid methodology, we carry out a first analysis identifying the problem, vortex shedding frequency and magnitude of those forces, then, we suggest and implement the required measures for mitigating the problem, like for instance some geometry modification or appendage to the submerged body.

Moonpool analysis & optimization

Moonpool is the name of the hole in the hull fitted to offshore vessels, seismic research for ROV operation or drilling on drill ships. The moonpool can have a significant size and can result on a very important resistance increase, it is therefore necessary to optimize its geometry for minimum resistance. The optimization process takes into account overall size, contour shape on ship bottom interface and water movement inside the moonpool since this is a key contributor to the resistance, this is normally called piston movement and could be in resonance at certain speeds, increasing its resistance significantly.

Thruster interaction simulation

Simulating how the thrusters interact among them and with the hull during DP operations. From this test we extract the thrust deduction coefficient for each thruster and direction, feeding the DP model with more accurate information.

Drag analysis for submerged bodies

Forces and moments on a submerged object like a ROV or a subsea template. This study can include the analysis of the artefact interaction with the sea bottom, due to the change of the pressure field due to the bottom effect, increasing the suction downwards among other phenomena.

Aerodynamic forces and moments

One the key contributing forces on ships during DP operations is the wind forces over the ship hull and superstructures, this effect is analysed for each direction modelling the shape of the superstructure with all its main features like cranes, davits and funnels. This type of analysis is also used to assess the smoke stack trajectory over the ship, and analysis of ventilation intakes and discharge grids.

Current loads

Current is a key contributor on the ship forces and moments during DP operations. It is important to accurate evaluate the performance of the ship under current, this issue is also of key importance for offshore vessels doing crabbing maneuvers.

Scour

Scour analysis is based on the evaluation of the shear of the sea bottom in the vicinity of Gravity base foundation. By means of the CFD analysis, we are able to predict the areas more likely to suffer scour phenomena as well as its intensity, analyzing different geometrical alternatives for scour minimization.

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