International Research Fellowship Program: Flow Focusing in Volcanic and Hydrothermal Systems: Experiments and Theory

国际研究奖学金计划使美国科学家和工程师能够在国外进行9到24个月的研究。该计划的奖项提供了联合研究的机会，并利用国外独特或互补的设施、专业知识和实验条件。该奖项将支持Richard F.Katz博士与英国剑桥大学Grae M.Worster博士合作的为期24个月的研究奖学金。他们的项目涉及专注于火山和热液系统的流动。火山和海底热液喷口喷发的流体对地球上的生命既是毁灭性的，也是至关重要的。它们的存在需要热流体在冷层中传输，而热量损失很小。这种传输可以通过将流体从广泛的扩散源区域局部流动到聚焦流动通道来实现。理解火山和海底热液喷口的一个重要问题是这种定位是如何发生的。PI和宿主假设了一种聚焦机制，在这种机制中，缓慢上升的流体冷却和沉淀局部降低了渗透率，将水流重新引导到狭窄的通道中。在这些通道中，流体运动迅速，从而避免冷却和沉淀。为了验证这一假设，他们提出了一系列物理实验和数值模拟。预计流体局部化的过程是一个反应性--动态不稳定性，一旦理解，就可以用简单的理论和既定的数学工具来表征。研究热液喷口的物理学将有助于我们理解这个反应系统可能是如何孕育了地球上生命的出现。预测在其他行星上存在这样的热液系统，将是寻找地球以外生命的有趣线索。

0602101KatzThe International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four-month research fellowship by Dr. Richard F. Katz to work with Dr. Grae M. Worster at Cambridge University in the United Kingdom.Their project involves flow focusing in volcanic and hydrothermal systems. Volcanoes and sea-floor hydrothermal vents erupt fluids with effects that are both devastating and critical for life on Earth. Their existence requires the transport of a hot fluid across a cold layer with very little loss of heat. This transport may be achieved by localizing fluid flow from a broad, diffuse source region to focused flow channels. An important question in understanding volcanoes and sea-floor hydrothermal vents is how this localization occurs. The PI and host hypothesize a mechanism of focusing in which cooling and precipitation by slowly rising fluid locally reduces permeability, redirecting flow into narrow channels. In these channels fluid moves rapidly and hence avoids cooling and precipitation. To test this hypothesis they propose a set of physical experiments and numerical simulations. It is expected that the process of fluid localization is a reactive--dynamic instability that, once understood, can be characterized with simple theory and established mathematical tools. Investigating the physics of hydrothermal vents will help us to understand how this reactive system may have hosted the emergence of life on this planet. The predicted existence of such hydrothermal systems on other planets would be an intriguing lead into the search for life beyond Earth.