Nanoscale Heat Transfer Due to Near Field Radiation and Nanofluidic Flows
Final rept. 1 Apr 2012-31 Mar 2015
CALIFORNIA UNIV IRVINE DEPT OF PHYSICS AND ASTRONOMY
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We have developed techniques for making individual nano-pipes with diameters in the range 20-500 nm and lengths of 20 microns. The nanopipes are fabricated by etching single ion tracks in either polymer or mica sheets. We have developed and calibrated mass spectroscopic methods to measure the flow of gases and liquids through the nanopipe over a wide range of temperature. We have identified transitions from laminar to turbulent flow, and from ballistic to hydrodynamic flow in the smallest pipes ever investigated. Because of the vacuum conditions at the low pressure end of our nanopipes, liquid flows through the pipe would spontaneously form a liquidvapor interface either inside the pie or near the exit. We developed a model which describes the details of this process this type of complex flow in evaporative refrigerators and in evaporation from porous media. All of our measurements can be accounted for assuming a slip length of zero, i.e. we see no anomalous flow in the nano regime. To further explore the role of slip, we have investigated the flow of superfluid helium 4. In superfluid, the flow velocities can exceed 10msec , and in distinct contrast to classical flows, the flow rate is essentially independent of pressure.