The current RWIND Simulation version recommends using the external CFD code OpenFOAM®. In particular, a special, natively compiled OpenFOAM® version from CFD Support called "OpenFOAM® for Windows", version 17.10 is utilised. The source code is based on the OpenFOAM® version distributed via openfoam.org and is included in the installation of the RWIND Simulation program.
The numerical solver is called "RWINDSimulationSolver" and it is related to the SIMPLE family of solvers. It is a steady-state solver for incompressible, turbulent flow, using the SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm.
Since OpenFOAM® is distributed under the GNU GPLv3 licence, the RWINDSimulationSolver is distributed under the same licence and its source code can be found in the RWIND Simulation installation directory, subdirectory "OF\src". For more information about OpenFOAM®, visit the CFD Support website or contact CFD Support directly using [email protected]. Trademark disclaimer: This offering is not approved or endorsed by OpenCFD Limited, producer and distributor of the OpenFOAM software via www.openfoam.com, and owner of the OPENFOAM® and OpenCFD® trade marks.
The result of the calculation is a three-dimensional field of velocity and pressure covering the entire computational domain, i.e. the wind tunnel. Pressure values on the model boundary (exterior surfaces of buildings) are then used to calculate the forces representing the wind load.
The used methods theoretically allow for a very precise simulation of such flow, provided that the computational mesh is sufficiently fine (e.g. tens of millions of mesh cells). However, such calculations are very time-consuming and thus expensive. Furthermore, the preparation of such calculations, i.e. topology clean-up and generation of an optimal mesh, often requires considerable effort and experience. RWIND Simulation has thus been designed to be very easy to use and to get approximate results on relatively coarse meshes in a very short time – typically within several minutes. If greater accuracy is desired, the user can obtain more precise results by increasing the mesh density – the capacity and performance of RWIND Simulation is limited only by the available memory and the number of processors/cores used for the parallel calculation.