FINE^TM/Marine, dedicated to marine applications, is the latest CFD product from NUMECA International. It offers high accuracy flow simulation results on arbitrary and complex geometries, leading to shorter design cycles. FINE^TM/Marine is developed in collaboration with Ecole Centrale de Nantes, Centre National de la Recherche Scientifique (CNRS), and NUMECA International. The synergy results in a product consisting of:

• Full-hexahedral automated unstructured mesh generator HEXPRESS^TM;
• Incompressible RANS solver ISIS-CFD;
• Flow visualization and analysis tool CFView^TM.

 

All is well integrated in a common graphical user interface.

 

	Mesh on Uilenspiegel: nozzle, V-brackets, and shaft details (courtesy IHC HOLLAND DREDGERS BV).

 

HEXPRESS^TM is an unstructured, non-conformal highly automated mesh generator. By making most of the grid generation steps completely automatic, HEXPRESS^TM reduces the meshing process to hours/days compared to days/weeks for common mesh generators. This makes it possible to perform RANS computations for industrial configurations on a daily basis.

HEXPRESS^TM captures the viscous layers with a body-fitted grid while maintaining the flexibility of an unstructured grid and the accuracy of an hexahedral element. The inflation technique ensures a smooth transition from the viscous layers to the outer mesh.

The ability to fully script and parametrize the mesh generation (python) enables the user to automate the mesh generation (in batch or interface) in a CFD cycle.  

 

The accuracy of the ISIS-CFD RANS solver is obtained using advanced features in turbulence modeling (i.e. nonlinear model and rotation correction, high and low Reynolds models, etc.), free-surface capturing methods with specific compressive discretization schemes for the concentration transport equation. This leads to a sharp capturing of the density discontinuity between air and water.

The solver also incorporates a mesh deformation algorithm for unstructured grids. Furthermore, the solver can handle the free movement of the solid bodies with 6 degrees of freedom. The unique adaptive grid refinement method (refinement - de-refinement, parallel, unsteady and with load balancing) opens a wide range of opportunities: capturing the free surface in time without the need of a fine mesh in the complete domain. Also, other refinement sensors such as pressure gradient and vorticity exist to locally refine the mesh.

Body motions are set-up in a straight way in the interface, including some predefined motions such as PMM Sway and Yaw, sinusoidal, gyration, and user-defined. A propeller is currently simulated with an actuator disk theory, but a full sliding grid capability is on the way. Don't hesitate to contact us for more information about the current status. Mooring simulations, wall roughness, advanced time stepping laws, wave generators (1st to 3rd order) are amongst the other features of FINE^TM/Marine.

 

A comparison between experimental results and those obtained with FINE^TM/Marine are done for a rowing wave. The figure to the right clarifies the problem.

The clip below shows the result obtained with FINE^TM/Marine for a single rowing stroke.

 

FINE^TM/Marine shows an excellent agreement for this test case: both the qualitative and quantitative trend are very accurately described. This shows the superiority of the package when dealing with complicated problems.

 

 The performance of the ISIS-CFD  is demonstrated in a computation at model and full scale for a fully appended hull configuration including free-surface, ducted propeller, brackets and rudder. The agreement between the blind computations and the full scale experiments is very satisfactory. CFD tools may be used with confidence for the design of complex ship hulls in full scale conditions. The scale effects on free-surface and of the structure of the viscous stern flow are not negligible and depend strongly on the stern geometries.

 

 

 

 

"For the last 8 years, we have been using 3 different CFD codes. FINE^TM/Marine is the first code that gave us confidence in the use of CFD tools, with results never differing much from experimental values.

Meshing with HEXPRESS^TM, although not without problems in the case of really complex bodies (e.g. superstructures), is a pleasurable experience - much more advanced than common meshing tools."

Dr. Piet Van Oossanen, Van Oossanen & Associates b.v., the Netherlands

 

"We regularly evaluate and exercise various CFD tools in research applications involving marine hydrodynamics. For problems requiring high degree of numerical accuracy, such as modeling of high-performance racing yacht hydrodynamics or simulation of flows around various marine vehicles for example, employing FINE^TM/Marine in such investigations has consistently yielded solutions that correctly capture the relevant physics and corresponding hydrodynamic loads."

Dr. Len Imas, Davidson Laboratory, Stevens Institute, US