While it seems that we are still a long way away from the cloaking devices seen in Star Trek, electromagnetic cloaking using metamaterials is now possible, at least in the laboratory. Not to be outdone, fluid flow and heat transfer have also recently joined the cloaking party.

For Submarines Stealth is Everything

Fluid Cloaking

Reducing the wake signature of submarines continues to be of great interest to the military in their quest for the perfect run-silent run-deep stealth vehicle. To neutralize the wake around a submarine researchers are proposing a large array of small jets that can suck and blow water as needed to counter the disturbance of the water due to the submarine's movement. For such a fluid cloak to work it would require a sophisticated control system that could monitor the flow field around the submarine and then in real-time direct the correct response of the water jets. I see a big role for CFD, first in evaluating whether it's possible to neutralize a wake. If it is, then CFD has more to do in determining the rules for the control system upfront or, more interestingly, in real-time as the submarine moves.

Heat Cloaking

Inspired by the recent advances in electromagnetic cloaking, French researchers have proposed an analogous cloaking theory for heat. Their idea is that using layers of materials configured with specific thermal diffusivity it is feasible to deflect heat around objects. They also propose that the technique can be used to concentrate heat where required. How did they develop this theory? With numerical heat transfer simulations.

The Future's Bright

Clearly Star Trek has blazed the trail on what might be possible in the future and now with the aid of numerical simulations the pace of advancement is quickening as more people get to play with ideas in virtual sandboxes.

Notes

• Fluid cloaking sources: New Scientist and Popular Science
• Heat cloaking sources: BBC and The Register
• Heat cloaking paper: Sebastien Guenneau, Claude Amra, and Denis Veynante, Transformation thermodynamics: cloaking and concentrating heat flux, Optics Express, Vol. 20, Issue 7, pp. 8207-8218 (2012)
• Your own virtual sandbox: Fluid flow and heat transfer tutorial for Caedium Professional