Juan K office’s range of tools enables us to carry out most of the design process in-house
PERFORMANCES DATA BASE
Our office developed 7 different Volvo Ocean Race design and record back all their performances.
This database combined with the actual wind data around the world are major inputs to feed our design process and design tools.
We have 15 years of wind and waves data around the world with a 0,3° of accuracy.
Our VPP can then be more accurate to test hull and rig candidates in any given sailing area.
VELOCITY PREDICTION PROGRAM
The aerodynamic model is embedded inside the VPP and has been fed by the different wind tunnel and aero CFD tests done in the past 10 years thanks to our involvement in the America’s Cup, the Admiral’s Cup 1999 and more recently the Volvo Ocean Race campaigns.
This model simulates the forces and moments of a given sail plan across a wide range of sail trims and wind velocities. Its output is then used by the VPP to quantify the required stability and balance for a given sailing condition.
The VPP [velocity prediction program] is a tool used at the very end of the analysis process where all the forces and moments tested, both aero and hydro, are put together and combined with the yacht’s righting moment to output the performance of a given candidate design across the range of wind speed and angles. We have developed our own VPP software that enables for a full freedom static solution that includes leeway and rudder angles.
The VPP output [usually called “polars”] is then taken to a higher level, a racing model that simulates the performance of a candidate design on a specified race course based on historical wind and current data. Both performance prediction programs have proven remarkably accurate in the Volvo Ocean Race.
COMPUTATIONAL FLUID DYNAMICS
Among the tools developed by our office, CFD modelling has become key in exploring the impact of subtle hull and appendage changes on performance.
Our work on America’s Cup, Volvo 70 and Maxi yachts has enabled to refine these tools considerably.
CFD is done with StarCCM+ from CD Adapco, a RANS/VOF code.
For shape optimization, we are coupling StarCCM+ with HEEDS for FSI structural integration (Fluid Structural Interaction).
Our 512 core cluster is providing under LINUX the large computing capacity required by these codes.
FINITED ELEMENT ANALYSIS
FEA: Finite element analysis is a method of describing the geometrical and mechanical characteristics of the whole yacht, as well as elements of it with the goal to simulate the behaviour of different structural solutions under a prescribed loading condition.
The output takes the form of stress and deformation maps, and the design is amended until both come within our objectives. This is key to obtaining a safe and capable structure at the lowest possible weight.
FEA also clarifies the critical interaction between rig and hull stiffness. A soft rig on a stiff yacht (or a stiff rig on a soft yacht) don’t make for a happy marriage.
Thus, we can supply the spar and rigging manufacturer with a clear objective that fits with the overall character and program of the yacht.
2D AND 3D DRAWINGS
3D modelling is vital for any project that relies on the analysis of different candidate shapes and structural solutions by different methods of simulations such as FEA and CFD.
The quality of the results of such analysis requires a state of the art modelling software. We use Pro/Engineer and CATIA as a central 3D tool that serves as the origin of all geometrical inputs for the FEA and CFD analysis. Furthermore, MAAT is used for the design of hull shapes and hydrostatic and stability calculations.
In-house software called CONDOR has been developed to perform a very accurate weight and centre of gravity estimation based on variable parameters such as hull shape, canting angle, rig configuration, weight, etc.
From this very 3D accurate model, will be extracted all the 2D deliverables needed for the boat yard to build the yacht.
As described in our Design Spiral process, it is very common that each drawings gets to be revised at least 3 times.