Wind Loads

ReFRESCO has been used for the calculation of wind loads on ships super-structures already since 2009. Several Verification & Validation studies have been done for different types of ships and offshore platforms with increasing level of detail. The limits of steady approaches and of geometrical detail possible to capture accurately are now know. Not only […]

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Propulsion

Propulsion of a ship deals with the final balance between resistance (friction, pressure and free-surface), propulsion forces and its inherent interaction. And often so-called Energy Saving Devices (or ESDs) are also present increasing (hopefully) the efficiency of this complex system. With ReFRESCO it is possible to analyze the complete propulsion of any system, using different fidelity […]

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Renewables

ReFRESCO has been validated for the performance  of offshore wind and current turbines. The efficiency calculated by ReFRESCO is in good agreement with measurements. Extensive studies have been performed on for instance the Southampton current turbine, Tocardo current turbine, NREL 5MW wind turbine and MARIN Stock Wind Turbine (MSWT). Furthermore, ReFRESCO is capable of calculating […]

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Submarines

Several studies have been done with ReFRESCO on submarines, mainly for manoeuvring performance studies, but also for resistance&propulsion analysis, design optimization and effect of free-surface. Several V&V (Verification & Validation) studies have been done within the community and together with other partners in NATO and other working groups comparative workshops. Submarines such as DARPA SUBOFF, BB1, BB2, […]

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Moonpools

“Moonpools” are open water-filled pools occurring in several vessels which exhibit very complex dynamic behaviour. And due to its size their dynamics can also effect the ship/platform behaviour where it exists. It is therefore an important and also complex problem to tackle in CFD: viscous-effects, low to high Reynolds number, moving structures, free-surface effects, wave […]

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Waves & Impacts

Wave generation and absorption (non-reflecting) are important issues in a CFD code tailored for Maritime applications. And also its effect on the structure loads, rapid structure impacts and structure motions is of paramount importance in the Seakeeping, Offshore and Renewable Energy world. Due to its developments in numerical schemes for free-surface, wave generation, wave absorption, […]

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Manoeuvring

Manoeuvring of free-surface or underwater vessels has always been a favourite topic within ReFRESCO application. And while the full unsteady full-scale appended and propelled-ship complex manoeuver in a sea-state (current and waves) is still a very expensive exercise with CFD (but possible …), CFD/ReFRESCO can already help in two ways: 1) by calculation of static or […]

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BioMimetics

Bio-mimetics is becoming important in the current world, where the hip on the usage of drones has made possible several technology pushes, by trying to mimic elements of the nature (insects, birds, fishes) into technology. Some members of ReFRESCO community are active in this area, and some applications have been made in order to demonstrate ReFRESCO techniques, its […]

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Fluid-Structure Interaction (FSI)

Hydro-structural problems can be approached with CFD in two manners: 1) as one-way coupling, where the hydrodynamic loads calculated with CFD are just used as input for structural (FEM) solvers; 2) as two-way coupling where the structure deformations are applied back to the geometries/grids in the CFD solver, and where an iterative procedure is used […]

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Scales-Resolving Simulations

Reynolds-Averaged Navier-Stokes (RANS) and Large-Eddy Simulation (LES) are two distinct mathematical formulations for the prediction of turbulent flows. While LES resolves part of the turbulent scales, RANS models the influence of the entire turbulent field on the mean flow, computing only average (time or ensemble) quantities. This results into a substantial reduction of computational demands […]

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Anti-Roll Tanks

The roll motion of ships operating in a seaway often limits operations. These limits could be due to the maximum acceleration, green water, capsize risk or just comfort, for example. Therefore, additional roll damping is often desired to improve the operability of ships. Several devices can be used to decrease roll motion, such as bilge keels, active stabiliser fins and U-shaped or free-surface anti-roll […]

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Propellers and Cavitation

Propellers and cavitation were two flow problems that ReFRESCO was suppose to tackle since the beginning of its development. Therefore, there are several CFD features, geometry and grid-generation tricks to perform accurate and fast calculation for these type of applications in ReFRESCO. Also, several papers on Verification and Validation exercises on wetted and cavitating flow on […]

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Current Loads

  When designing offshore platforms or ship offloading units, one of the aspects to have into account is the loads due to the currents. The calculation of the loads on any object for any heading angle was one of the first research and commercial applications of ReFRESCO. Due to the experience gained with the several […]

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Free-Moving Objects

Most of the problems in the maritime world involve objects (ships, submarines, offshore platforms, renewable energy systems) which move freely due to the hydro and aerodynamic loads they are subject, and their structural properties. While solving the fluid (Navier-Stokes) equations permit to compute these loads, solving the structural equations (or equations-of-motion or rigid-body dynamic equations) […]

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Ship Wave Pattern

In these pictures (and video in the slider) one can see the steady wave pattern calculated around two ships. The calculations are done using a two-phase URANS approach, where both water and air phases are solved and a water volume-fraction transport equations is solved. This is usually called a surface-capturing technique (or sometimes erroneously also called […]

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