User Guide: Wind Analysis using LBM (Lattice Bolzmann Method) Solver
The LBM solver has the ability to deal with many CAD types and is generally more robust than many solvers in terms of cleanliness of the geometry, where open geometry, poor faces and small faces don’t really matter. That said in the odd occasion you have issues or error, if you inspect the geometry and don’t find anything fundamentally wrong, an STL can normally be uploaded which may mitigate any issues you are experiencing.
The geometry can be uploaded in the same way as you would normally upload a geometry to the SimScale platform, simply click the plus sign next to geometry in the item tree in the left hand panel.
From here the user can upload a geometry from their local machine or import from OnShape directly.
Creating a simulation
To create a simulation using the LBM (Lattice Boltzmann) method, the user simply needs to create a new simulation selecting the Incompressible LBM simulation type. First, select the plus in the item tree next to simulations and select the Incompressible LBM simulation type.
This simulation can then be re-named appropriately, and the turbulence model selected. More about the selection of unsteady turbulence models available in this simulation type can be read in the documentation.
To define how air is entering and exiting the ‘domain’ or the ‘fluid region’, we need to define boundary conditions. This consists of an inlet face, and outlet face and other faces, usually a combination of no-slip walls or slip walls for non-interfering boundaries. The first task in this process is to define the size of the fluid domain, and this is done in the geometry section.
Geometry primitives can be added to be used later as mesh refinements or export regions, however there will always be a geometry primitive called ‘External Fluid Domain’ which can be edited to control the size of the fluid region.
The next step in the process is to go to the boundary condition section and setup the velocity inlet, pressure outlet and other conditions.