Use the Simulation Settings to define how the wind tunnel flow runs. The Simulation Resolution controls the speed and accuracy of the wind tunnel flow. The Units settings control the model size and displayed dimensions.
Simulation Resolution
The wind tunnel is transparently divided into a grid made up of small pieces called "voxels." The calculation works by solving the flow equations on each voxel and then assembling them to form the overall solution. Flow Design transparently performs this operation by automatically determining the voxel sizes based on the model and the wind tunnel.
In some models, it may be necessary to use a smaller voxel size to better capture the flow around complex geometric features. This is an example of a grid that uses voxels that are too large for the geometry to produce good results:
Notice that very few details of the model are captured in the flow. The voxels are so large around the car that you can see them in the results!
When smaller voxels are used, the results are much clearer:
In this case the flow is not artificially affected by the simulation resolution, and voxel shapes are not visible around the car model. The result is a much sharper flow distribution.
To change the resolution of the grid, click Simulation from the Ribbon, and adjust the Simulation Resolution value.
- To use a lower-resolution grid (with larger voxels), drag the slider toward Low (Faster). This causes the solution to run faster, but creates a solution that may be less accurate.
- To use a higher-resolution grid (with smaller voxels), drag the slider toward High (Slower). This causes the solution to run slower, but creates a solution that may be more accurate. If your geometry has small features, it is a good idea to use a higher-resolution grid to accurately capture the flow around such features. Note that if you specify a resolution that exceeds the RAM resources of your computer, Flow Simulation automatically reduces the resolution to a value that can be safely run.
When comparing results from multiple wind tunnel flows, it is important that you use the same Simulation Resolution. Different values can produce different results values, making it difficult to accurately compare designs.
Units
To rescale the wind tunnel and model size, change the Model Dimensions. For example, if the wind tunnel is 1 m long, and you change the Model Dimension to mm, the wind tunnel becomes 1 mm long. Because the length dimensions in the Information section are given in either meters or inches, the length of the wind tunnel is reported either as 0.001 m or 0.039 inches, respectively.
To change the units displayed in the legend and Information section, change the Display units. This value does not change the dimensions or physical size of the wind tunnel and model.
- Select Metric to view dimension values in meters and velocity in m/s.
- Select English to view dimension values in inches and wind velocity in ft/s.