The Froude number, Fr, is a dimensionless value that describes different flow regimes of open channel flow. To predict bed-material transport when bedforms are present it is also necessary to be able to separate the resistance to flow due to the bedforms (form drag or form resistance) from that due to direct shear on the sand grains at the bed surface (skin friction). Plane bed is characterized by high suspended sediment transport rates and a Froude number in the range 0.8 to 0.95. Recognition of sedimentary structures generated by bedforms provides information about the strength of the current, the flow depth and the direction of sediment transport. These flow states relate to a parameter, the Froude number (Fr), which is a relationship between the flow velocity (y) and the flow depth (h), with g the acceleration due to gravity.
The near shore Froude Number relates bed forms to water velocity and depth The most common direction for the wind to blow from in Maine in the summer is from the southwest Tombolos form as a result of wave refraction. At the critical depth, when the flow velocity is also critical, the Froude number is unity. A flow can change from subcritical downstream to supercritical, or from supercritical to subcritical, given the presence of suitable flow controls, for example, changes in the shape and slope of the flow boundary. Vocabulary words for Topic 06 – Bedforms. Low Froude Numberflow: ____ Geometry, out of phase. High froude Number flow: ____ geometry, in phase.
The Near Shore Froude Number Relates Bed Forms To Water