Studies on gravitational spreading currents
Creators: name: Chen, Jing-Chang
Publisher: name: California Institute of Technology
Year: 1980

description: The objective of this investigation is to examine the buoyancy-driven gravitational spreading currents, especially as applied to ocean disposal of wastewater and the accidental release of hazardous fluids, such as liquefied natural gas.

A series of asymptotic solutions are used to describe the displacement of a gravitationally driven spreading front during an inertial phase of motion and the subsequent viscous phase.  Solutions are derived by a force scale analysis and a self-similar technique for flows in stagnant, homogeneous, or linearly density-stratified environments.  The self-similar solutions for inertial-buoyancy currents are found using an analogy to the well-known shallow-water wave propagation equations and also to those applicable to a blast wave in gasdynamics.  For the viscous-buoyancy currents the analogy is to the viscous long wave approximation to a nonlinear diffusive wave, or thermal wave propagation.  Other similarity solutions describing the initial stage of motion of the flow formed by the collapse of a finite volume fluid are developed by analogy to the expansion of a gas cloud into a vacuum.  For the case of a continuous discharge there is initially a starting jet flow followed by the buoyancy-driven spreading flow.  The jet mixing zone in such flows is described using Prandtl's mixing length theory.  Dimensional analysis is used to derive the relevant scaling factors describing these flows.
description: © 1980 W. M. Keck Laboratory of Hydraulics and Water Resources. California Institute of Technology.

The writer wishes to express his deepest gratitude to his
thesis advisor. Professor E. J. List. who offered much guidance, encouragement, and valuable criticism throughout this investigation. Several talks with Professors Vito A. Vanoni and Norman H. Brooks always gave a long lasting comfortable feeling, which is especially needed in the life of a graduate student at Caltech. His office mate. Dr. Greg Gartrell, Jr., helped in many phases in accomplishing this research and shared many ups and downs of the research life.
The writer would also like to thank Mr. Elton F. Daly, supervisor of the Shop and Laboratory, and Mr. Joe Fontana for their assistance in designing and constructing the experimental set up and their patience in teaching him how to play cribbage during lunch time. Appreciation is also due Mr. David Byrum, who helped in setting up equipment and taking photographs; Mrs. Adelaide R. Massengale, who typed the manuscript; and Mrs. Joan Mathews, who typed some parts of the earlier draft. For financial aid of his graduate studies at Caltech, the writer is grateful to The Li Foundation Inc., New York for a two-year (1974-76) Fellowship and to the California Institute of Technology for Graduate Laboratory Assistantship (1974-75), and Graduate Research Assistantship (1975-present). The
financial support for this research work from the National Science Foundation through Grant Nos. GK-35774X, ENG75-02985, and ENG77-27398 is greatly appreciated.
Finally, the author wishes to thank his parents and every
member of his family for their continuous encouragement for a higher education over the past years, and his wife, Yuan-Lin, for her sacrifice in putting up with most of her time alone, days and nights. Without the strong spiritual support from each member of the family, completing this research work would have been impossible. This thesis is dedicated to his beloved Grandfather.