From the Labs: Information Technology

More-Realistic Fluid Animations
A new approach helps computer-animated fluids flow more naturally

Source: “Stable, Circulation-Preserving, Simplicial Fluids”
Mathieu Desbrun et al.
ACM Transactions on Graphics 26(1)

Results: Researchers at the California Institute of Technology have developed a new geometric approach to simulating fluid flow that’s more realistic.

Why it matters: Numerical approaches commonly used in computer animation and in aerodynamics simulations contain inaccuracies that can cause graphically depicted liquids to appear to flow unnaturally. For instance, when used to model whirlpools, these equations predict an exaggerated decrease in energy, so animations of swirling water slow down for no apparent reason. Animators need to spend time correcting these errors by hand. A numerical treatment that better respects liquids’ actual behavior could save animation studios time and money.

Methods: The researchers used a new type of mathematics called discrete differential geometry to calculate the flux of a flowing liquid, a property that determines the velocity and position of the liquid at any time. The researchers say that because their equations use flux, rather than just fluid velocity, they more accurately capture the behavior of swirling liquids.

Next steps: The new approach should yield simulations that better predict the flow of fluids–say, water or air turbulence around planes or boats. Eventually, the approach could be incorporated into software for movie studios, but that will require more research on how to modify the equations to simulate a wider range of natural phenomena.

Source: “Nano/CMOS Architectures Using a Field-Programmable Nanowire Interconnect”
Gregory S. Snider and R. Stanley Williams
Nanotechnology 18: 035204

Results: Hewlett-Packard Labs researchers R. Stanley Williams and Greg Snider have redesigned the chips known as field-programmable gate arrays to make room for eight times as many transistors, without shrinking the transistors themselves.

Why it matters: As electronic devices, such as transistors, grow smaller, engineers can pack them closer together, producing faster and more powerful computer chips. In the next decade, however, the standard techniques for shrinking transistors will run up against fundamental physical limits, so engineers are looking for new ways to increase the density of chip circuitry.

Methods: In today’s chips, some of the silicon real estate is taken up by aluminum-wire interconnects that supply power and instructions to the transistors. To make room for more transistors, the HP researchers designed a chip whose wires are on top of instead of in between the transistors. They used what they called a “crossbar structure,” a sort of nanoscale wire mesh developed at HP. Each junction in the mesh acts as a switch that controls the flow of electrons to and from the transistor beneath it.

Next steps: The researchers are developing a laboratory prototype that uses the design, and Williams expects it to be complete by the end of the year. By 2010, he says, the technology should be ready for manufacturing.