Fact Sheet
US Army Corps of Engineers
U.S. Army Engineer Research and Development Center
February 2003
Public Affairs Office
3909 Halls Ferry Road Vicksburg, MS 39180-6199 (601) 634-2504
Precision Flow Table for Investigative Studies
Purpose: To
summarize capabilities of
the Coastal and Hydraulics Laboratory's (CHL) Precision Flow Table
developed for rapid and low cost preliminary examination of complex steady flow problems.
Background: The precision table maintains a
constant flow discharge across a horizontal portion
of the table. Small-scale models depicting either
idealized flow boundaries or portions of actual
projects are placed on the glass horizontal test
section of the flow table. Flow patterns created by
the scale model solid boundaries, such as regions
of flow separation, are quantified using a laser
Doppler velocimeter (LDV) located beneath the
horizontal section of the table. Complex flow
patterns can also be visualized using traditional
techniques of dye injection, surface tracers, and
bottom tracers as illustrated in the photograph of a
three-dimensional model of Cook Inlet, Alaska.
Facts: The precision flow table provides an efficient and cost-effective tool for examining complex flow patterns
formed by solid boundaries such as jetties, bulkheads, groins, and rocky headlands. Flow modifications stemming
from changes in boundary or upstream configurations are easily evaluated, and this aids project study optimization by
quick identification of unsuitable alternatives. Flow table studies are predominately for screening ideas and
alternatives, and the studies do not provide final design and project optimization, which should be accomplishing
using more sophisticated tools such as large physical models or numerical simulations. The flow table simulates only
current flow situations; waves are not included. Types of studies that can be conducted with this facility include: (1)
Visualizing flow patterns in large estuaries, inlets, or where flow separation and three-dimensional flow occurs; (2)
Obtaining velocity measurements near structures and in turbulent regions associated with flow separation at solid
boundaries; (3) Quantifying flow conditions in idealized cases for use in validating numerical modeling techniques;
(4) Quickly examining project impacts due to structure modification, addition, removal, or relocation; and (5)
Observing the extent of flow three-dimensionality in order to determine the correct numerical modeling approach.
The advantages of flow table studies include: flow conditions can be controlled precisely; the small size (4 ft wide
by 8 ft long) of the table allows rapid (and inexpensive) changing of solid boundaries; complex bathymetry can be
recreated at scale for minimal costs; and study costs are low. Disadvantages are as follows: currents are steady in
time; waves can not be simulated; models of actual projects must be geometrically distorted which introduces some
scale effects; and in most cases studies will not produce final design recommendations.
Points of Contact: For additional information, please contact
Dr. Steven Hughes at 601-634-2026 ( ), or
Mr. Dennis Markle at 601-634-3460 ( )"> ).