Monday, April 15, 2013

Wind Energy and Wind Farm CFD simulation show that Converge is not only for Internal Combustion Engines (ICE)

We got some interesting data a little while ago.  It was from CSI, makers of Converge, but it wasn’t of an internal combustion engine (ICE).  We normally associate CSI and Converge with ICE.  Instead it was of a wind farm, you know green energy and windmills.  So we cracked open the data and came up with some nice visualizations of the data using EnSight.

We used texture maps to make the terrain look like rolling grasslands, clip planes to show the velocity in a fixed altitude plane, and if you look carefully you can see the mesh adapting to moving blades as well as to greater or lower variable gradients.  There’s a 2nd viewport showing the pathlines of the flow.

We liked that, but thought we’d go a little deeper and use a more advanced technique.  What if we changed the clip transparency to be nearly invisible for low speed flow and more opaque when things go interesting. This particular animation, the clip plane’s opacity is changed dynamically through the velocity variable so that regions of high velocity are opaque, and regions of low velocity are translucent. The alternative view shows streamlines seeded from the turbine blade.

In this particular visualization, the clip plane in the main view is colored with velocity and the the engineer can inspect the changing grid resolution in response to the flowfield gradients. In the alternative view, inspection of turbulent kinetic engery isosurfaces can help yield information regarding the influence of the various large obstacles in the field (hills, towers, etc) which are generating additional turbulence.
EnSight is useful for looking at this kind of data. We could have gone further and done a keyframe animation fly-through as well, but that would have probably looked like showing off.  (keyframe animated Converge model available here).
We didn’t want to lose the main story here, Converge is not just using its advantages for internal combustion engines anymore.
P.S. – Converge data is almost perfect for EnSight, its CFD, its transient, and Converge’s moving parts and adapting mesh and growing model sizes are no problem for EnSight.  What don’t we like, well its full of polyhedrals and EnSight 10.0 and prior versions convert polyhedrals to other more primitive types which takes more memory and is slower for EnSight. But in EnSight 10.1 coming in late spring early summer we will intro duce native polyhedral element support.  Memory usage and performance are expected to improve.   Want to see more models solved with Converge and post-processed using EnSight, visit the Converge page in our video gallery.
P.P.S – if you make CFD data, for example you have a CFD solver that outputs data in a form EnSight can read and want to send an interesting dataset like CSI did, we’d like that.