NEWPAN

Existing panel methods for the prediction of aerodynamic characteristics have been in widespread use within the aerospace industry for the last 20 years. They remain by far the most practical tool for the analysis of complex 3D configurations at subsonic speeds, with a mass of validated data from a range of applications confirming their accuracy and versatility. Since the introduction of these codes, however, significant advances have been made in solution procedures and computer technology.

The basic formulation of NEWPAN is similar to other well established panel methods. The surface of the vehicle is represented by a set of abutting facets or panels, each carrying a constant source and/or doublet singularity distribution. NEWPAN uses a combined boundary condition formulation to distinguish between two types of components - thin and thick. The thin (two sided) component carries doublet singularities and has a Neumann boundary condition imposed; the thick (single sided) component carries both source and doublet singularities and has a Dirichlet boundary condition imposed.

Each panel may be quadrilateral or triangular, and thick or thin. Hence a hybrid surface grid may be utilised, using a mixture of structured components composed of quadrilateral panels and unstructured components composed of either triangular or quadrilateral panels, or both. The flexibility and ease of generation of unstructured grids makes them ideal for the modelling of complex configurations where a fully structured surface grid would be time consuming to generate. Structured grids are ideal for components such as wings where there is typically high surface curvature in one direction only, and where an optimum panel distribution leads naturally to quadrilateral panels of moderate to high aspect ratio. A hybrid model featuring selective use of structured and unstructured components achieves the best of both worlds.

In common with other panel methods, the core NEWPAN method is restricted to the computation of inviscid, incompressible, irrotational flow. Iterative compressibility corrections extend its applicability to high subsonic Mach numbers. Boundary layer solvers provide viscous prediction and correction. A non-coupled integral boundary layer calculation procedure known as PANBL provides robust and accurate predictions of flow transition and separation. Its use with NEWPAN provides a proven method for aerofoil design where gross flow separation is to be avoided. A strongly coupled quasi-simultaneous viscous-inviscid procedure, capable of predictions up to and beyond Clmax is also available for use in conjunction with NEWPAN.

NEWPAN has been developed using modern, object-oriented programming techniques which benefit both developers and users alike. For instance, NEWPAN has no limit placed upon the maximum problem size; all arrays are dynamically allocated in C++ as opposed to older rival codes written in Fortran.

Panel method solutions to the flow about complex configurations are inherently fast, especially in comparison to volume based methods. NEWPAN is especially fast; it features a novel accelerated block-iterative matrix solver and solutions in parallel on multiprocessor systems. The solution to the complete Formula One car shown here is obtained in about two minutes on a typical single CPU desktop PC.

The speed, accuracy, flexibility and ease of use of NEWPAN allows CFD to become an integral part of the design process. Flow Solutions have always placed strong emphasis on providing engineers with tools for design, above and beyond analysis. For example:

• the use of inverse design (prescribe a pressure distribution/boundary layer development and compute the shape necessary to achieve it) as provided by NEWPAN2D
• the integration of NEWPAN with 3D optimisers (viable even for the optimisation of complex configurations thanks to the extremely rapid execution of NEWPAN);
• the coupling of NEWPAN with finite element structural solvers for the solution of aeroelastic problems (again benefitting from the rapid execution of the NEWPAN solver).

• aerospace: widely used by QinetiQ (formerly DERA, the UK Government agency for aerospace evaluation and research) at several establishments. Extensive validation work has been performed;
• automotive, especially motor racing. NEWPAN has established almost complete dominance as the panel method of choice in Formula One aerodynamic design (often complemented by a Navier Stokes code).
• marine: adopted in a range of applications from military submersibles to yacht racing, in particular the America's Cup. NEWPAN and its derivative PANSAIL provide solutions both above and below the waterline (e.g. hulls, keels and sails).