Pumping Fluid by a Ratchet (image) American Institute of Physics Share Print E-Mail Caption When a fluid is squeezed and expanded repeatedly between two sawtooth-like boundaries, a net flow is generated to the right. Credit B. Thiria & J. Zhang Usage Restrictions This image may be used only with appropriate caption and credit. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.