Hydrodynamics CFD simulation, Coupled with FEA for FSI Analysis of Marine and offshore structures
Hydrodynamics is a common application of CFD and a main core of Esimlab expertise. CFD allows the steady-state and transient hydrodynamics of hydrofoils, submersible vehicles, propellers, impellers, marine structures and marine plant to be computed with extremely high levels of accuracy. System properties such as mass flow rates and pressure drops and fluid dynamic forces such as lift, drag and pitching moment can be readily calculated in addition to the wake effects. This data can be used directly for design purposes or as in input to a detailed stress analysis.
Hydrodynamics simulation and optimization is one of the Esimlab’s core expertise. Deep knowledge and experienece combining with advanced CFD and FEA software enable us to handle any problem with any level of complexity in very short time. We Use CFD tools such as Numeca Fine/Marine, Ansys Fluent, Siemens Star-ccm+ and FEA Tools such as Abaqus, Nastran and LS-DYNA with combination of very experineced engineers to help our customers in:
Real World Simulation with Couple using of CFD and FEA
Using cutting edge solver technology, Esimlab’s customers have been able to tackle some of the most demanding problems that the marine industry has to offer, allowing us to predict how designs will react in operation, before budget is committed to the construction of expensive prototypes. Esimlab’s Engineering team provides analyses ranging from: ship keeping, slamming and sloshing; wave and wind loading on offshore and underwater structures; oil and pollutant dispersions to cavitation control and propulsion system optimization.
Esimlab hydrodynamics Simulation Service include:
CFD and FEA based Offshore and marine engineering for fixed structures
Using FEA and CFD software for innovation, flexibility and efficiency in marine and offshore structural engineering for oil and gas production structures and fixed offshore wind turbine support structures, Esimlab engineers can gives you the optimal basis for critical engineering decisions during the entire lifecycle of your asset, be it a topside, jacket, jack-up, or offshore wind turbine support structure. We Use CFD tools such as Numeca Fine/Marine , Ansys Fluent, Siemens Star-ccm+ and FEA Tools such as Abaqus, Nastran and LS-DYNA with combination of very experineced engineers to help our customers in:
- Concept modelling for design optimization in offshore structural engineering
- Non-linear soil-pile structure and Fluid-structure interaction analysis with Coupling of best in class FEA and CFD softwares
- Static and dynamic structural analysis incorporating environmental load calculation (wind, waves, current: Hydrodynamics and Aerodynamics effects)
- Wide range of analyses within offshore and marine structural engineering: load-out, transportation, launching, installation, in-place analysis, code checking, fatigue, earthquake, progressive collapse, accidents, explosions
- Buckling analysis
Assessing wave impact loads on ships and offshore structures and superstructures
Wave impacts are among the most extreme loads occurring on ships and offshore structures. Even if extreme loads are taken into account for design rules, understanding non-linear impacts and computing water on deck or on superstructures remains a major design issue. Bow shapes and design, deck layout including deflectors must also be taken into account to protect equipment and ensure the safety of the crew. Transient behavior of strcuctre investigated by using combination of FEA and CFD tools including Hydrodynamics and Aerodynamics effects.
FEA-CFD based floating and gravity-based structures design including Hydrodynamics and Aerodynamics effects
In modern industrial product design, multi-physics simulations are carried out to capture the interaction between different physical phenomena. A Fluid Structure Interaction (FSI) analysis describes the response of a physical structure to the fluid flow. For this, the dynamics of both the fluid and the structure must be modeled. More advanced applications of multi-physics analyses can involve thermo-fluid-dynamics to be coupled with electromagnetism and acoustics.
Using numerical methods it is possible to understand and predict fluid-structure phenomena. This multi-physics simulation requires the coupling of two or more simulation tools such as CFD, FEM, electromagnetic or acoustic solvers.
An FSI analysis can involve:
1-way FSI: pressure and temperature distributions calculated via CFD are transferred to a structural model as load conditions. The structural deformation does not affect the flow field
2-way FSI: a transient analysis that couples CFD and FEM. At each time-step, loads are transferred from CFD to FEM and deformations are transferred back from FEM to CFD in an iterative process
Esimlab engineering team with use the market-leading software for hydrostatic, hydrodynamic and strength analyses of ships and floating offshore structures to help customers working with floating structure design and modification efficiently produce high quality hydrodynamic analyses to give an accurate prediction of resulting deformations and stresses.
- Coupled FEA-CFD based simulation of floating structures, including barges, FPSOs, semi-submersibles, TLPs, spar buoys and gravity-based structures.
- Radiation/diffraction BEM Based software combined with FEM (finite element method)
- Floating wind turbine Simulation and analysis.
- Hydrodynamic motion analysis in frequency and time domain
- Inclusion of mooring and risers in design and optimization of motion characteristics
- Intact and damaged stability analysis
- Static and dynamic structural analysis in frequency and time domains
- Ultimate Limit State (ULS) Code checks for beams and stiffened plate/shell
- Fatigue analysis for different component of floating structure
Transient resistance, propulsion, sea-keeping and maneuvering simulation including FSI and hydrodynamics effect
CFD analysis can optimize ship hull design, sail shape and propeller blades. Analysis predicts water free surface around the ship hull which helps to accomplish optimal hull shape with low hydrodynamic drag. CFD provides information to optimize sail shape and location for efficient and stable ship. CFD analysis can optimize propeller blade design for energy efficient ship and avoid cavitation on the blades.
Wave-making resistance is a form of drag that affects surface watercraft, such as boats and ships, and reflects the energy required to push the water out of the way of the hull. This energy goes into creating the wave. For small displacement hulls, such as sailboats or rowboats, wave-making resistance is the major source of the marine vessel drag. CFD analysis is used to lower ship hydrolic drag by optimizing ship body shape.
A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the airfoil-shaped blade, and a fluid is accelerated behind the blade. Optimization of propeller blade shape will require CFD analysis.
Marine propulsion system designers rely on the combination of CFD and FEA software for fatigue, strength and vibration analysis. Proper propulsion system/components analyses during the design phase help avoid delays in delivery and damage problems in operation, thereby reducing expensive off-hire. Professional and reliable software is essential for the design of a robust system.
Esimlab has vast experience in the modelling of hydrodynamics using CFD simulation in a wide range of applications. The experienced CFD staff can offer an accurate and detailed analysis of the flow and be able to identify viable areas of improvement for implementation and design.This Simulation can be used to model:
- Hydrodynamic Interaction between Bodies: shielding effects, Forward speed effects
- Shielding effects of a pier adjacent to a ship, an important aspect in the design of breakwaters and how they affect mooring systems.
- Design and analysis of mooring systems, including intermediate buoys and clump weights
- Motions analysis of FPSOs (Floating production storage and offloading)
- Calculation of shielding effects of ships and barriers
- Multiple body interactions during LNG transfer
- TLP tether analysis
- Dropped object trajectory calculations
- Concept design and analysis of wave and wind energy systems including multiphase condition including hydrodynamic effects
- Simulation of lifting operations between floating vessels
- Discharging landing craft from mother ships
- Transportation of large offshore structures using barges/ships
- Float over analyses
- Motion analysis of spar vessels
- Static and dynamic initial stability including the effects of mooring systems and other physical connections
- Coupled Hydrodynamic CFD Simulation with structural finite element analysis to Simulate Transient strcutural behavior in irregular waves
- Coupled cable dynamics in static and dynamic analysis to modeling of mooring system loading and response in deep waters.
- Dynamic positioning system
- Towing force provided by a tug
- Damping system with unusual characteristics
- Suction force between two ships close together, or between a ship and the sea bed
Ship Stability and Safety analysis including Hydrodynamics and Aerodynamics effects
Numerical investigations carried out on ship intact and damage stability using FEA and CFD. Many intact stability cases dealing with parametric rolling are effectively investigated with numerical simulations. combination of sophisticated FEA and CFD software is used by Esimlab’s engineering team in many numerical investigations to effectively model both ship rolling and also internal flooding on decks:
- Intact stability
- Parametric rolling computations
- Damage stability
- Survival times
- Flooding simulations
- Accident simulation for the stability analysis of ship
Various factors can form operational limits for the use of a vessel and ship oprability. Often these are excessive ship motions or accelerations, which can make human work in certain situations impossible or unsafe. On special vessels such limits can be connected to operation of certain equipment. On an offshore vessel or a research ship a limiting factor can be e.g. water motion in a moon pool. Many of these factors or parameter values can be directly measured in model tests, or the number of occurrences of an undesired event over time (shipping of green water, slamming) can be counted in a model.
Operability limits can also be of more functional nature, e.g. holding a vessel steady against an offshore windmill foundation, or launching and recovering a dinghy safely onboard in seaway. Many issues related to dynamic stability of the vessel in waves, e.g. steerability of high speed marine vehicle in waves or the dynamic stability of a vessel against excessive heeling in extreme sea states:
- ship motions and accelerations Simulation
- shipping of green water analysis
- slamming impacts simulation
- sloshing simulation
- steerability in waves analysis
- DP -capability simulation
CFD Simulation of Fluid Free Surface for Hydrodynamic Analysis
Liquids are everywhere and used for fueling, cooling, heating, oiling, or other purposes in electro-mechanical and hydraulic systems. When in a moving vehicle (whether on or off-road, on sea/rivers, in air or space), they are subject to motion and resonance modes and in specific conditions can even produce extreme loads. Understanding liquid motions in tanks, with or without gravity, defining extreme loads of water, oil, fuel or Liquid Natural Gaz in a containment, is crucial for security issues.
Whether your application involves sea, air or land transport, tank resistance, steady fuel delivery, mass distribution and other design parameters are your concerns.
The primary challenge for numerical simulation is to take into account multiphase flows (free surface without diffusion), compressible flows and fluid/structure coupling when needed.
Esimlab’s engineering team use a virtual Water Channel for free surface simulations. It can be used to analyze the flow around ship hulls and predict their resistance, seakeeping, loads on components, and the downstream wake of both surface and submerged watercraft. The adaptive refinement algorithm can also detect and refine dynamically and automatically the ship wake and the free-surface of the fluid.
We can simulate Rigid Body Dynamics behavior of moving parts, such as boat dynamics with six degrees of freedom. This simulations allow us to studt the effects of the change of the heave on the roll or yaw angle or the effect of an increasing inlet flow on the roll angle of a boat in transient simulation. It is also availble to simulate moving parts with enforced behavior such as those required for boat maneuvers or carrier ships with real rotating propellers or modeled ones.
Esimlab experienced engineering team use CFD software’s multiphase capabilities such as Siemens Star-ccm+, Ansys Fluent and Numeca Fine/Marine for hydrodynamic analysis on the submerged boat region and aerodynamic analysis on the wind exposed region to be performed at the same time. Moreover, co-simulation with FEA structural solvers, such as Abaqus, Ansys and MSC Nastran used to investigate sail deformation.
for studying seakeeping of boat hulls, predicting floating buoys behavior, or measuring the impact of the waves on off-shore structures such as oil platforms or bridge pillars, special purpose CFD and FEA based softwares used to simulate a wide range of sea conditions. also it is possible to simulate a porous volume to model the beach and study wave dissipation on the coast.
Hydrodynamics And HydroAcoustics simulation for AIV (Acoustic Induced Vibration)
AIV (Acoustic Induced Vibration) refers to structural vibration excited by intense pressure fluctuations in a compressible flow stream. Process plants have a number of requirements for abrupt pressure reductions, which invariably generate some amount of acoustic vibration. This is normally accomplished through the use of the following:
- Blow down valves and restriction orifices
- Relief valves
- Pressure reducing valves
- Compressor recycle valves
The pressure reduction process induces turbulent pressure fluctuations in the flowing medium, which in turn excites the downstream pipe wall, causing stresses and potentially fatigue failure. The intensity of vibration tends to increase with mass flow rate, velocity, and pressure loss. AIV failures are known to occur preferentially at non-axisymmetric discontinuities in the downstream piping, such as at small-bore branches and their welded supports.
Esimlab’s engineering team use combination of advanced CFD and FEA toold to predict AIV failures and provide remedial actions. This methodology starts with the identification of processes requiring analysis and concludes with recommendations to reduce dynamic stress levels where the potential for fatigue failures puts your facility at risk.
Special application of Hydrodynamics simulation: Hydroplaning
Hydroplaning takes place when a tire is lifted off the road by a wedge of water getting trapped under the leading edge of the tire as it travels through a puddle of water. The speed at which a tire hydroplanes is a function of the vehicle velocity, water depth, vehicle load, tire pressure, and most importantly the tread pattern depth and design. When the tire is unable to remove sufficient water from its path, water lifts the tire completely off the road, causing the vehicle to lose control.
It is important to gain insights on the interaction of a tire with a film of water in order to diagnose the onset of hydroplaning and minimize the tire’s propensity to hydroplane. A coupled Eulerian-Lagrangian methodology, using a multi-material Finite Element formulation within advanced FEA software, is used to analyze the interaction of a tire with the water film. The effect of various parameters on the onset of hydroplaning are investigated using the methodology.
CFD Optimization of Hull Form Including Hydrodynamics considerations
The hullform of a ship is decisive for its energy consumption and efficiency in that a large part of the overall resistance is determined by form effects and the aft body shape influences the propulsive losses. The shape related aspects are traditionally the domain of a ship model basin. While in the past numerous physical ship models have been created and tested in a towing tank to find the optimal solution, this role has been taken over by CFD, numerical methods which allow analysing the performance of a ship hull before the first model is built. Esimlab Engineering team use advanced CFD and Optimization softwareand methods to compute hull resistance at different stages of a design.