The Rouse number (P or Z) is a non-dimensional number in

fluid dynamics In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids— liquids and gases. It has several subdisciplines, including ''aerodynamics'' (the study of air and other gases in motion) a ...

which is used to define a concentration profile of suspended sediment and which also determines how

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand ...

will be transported in a flowing fluid. It is a ratio between the sediment fall velocity

w_s

and the upwards velocity on the grain as a product of the von Kármán constant

\kappa

and the

shear velocity Shear velocity, also called friction velocity, is a form by which a shear stress may be re-written in units of velocity. It is useful as a method in fluid mechanics to compare true velocities, such as the velocity of a flow in a stream, to a veloc ...

u_*

. :

\mathrm = \frac

Occasionally the factor β is included before the von Kármán constant in the equation, which is a constant which correlates eddy viscosity to eddy diffusivity. This is generally taken to be equal to 1, and therefore is ignored in actual calculation. However, it should not be ignored when considering the full equation. :

\mathrm = \frac

It is named after the

America The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

n fluid dynamicist Hunter Rouse. It is a characteristic scale parameter in the

Rouse Profile Rouse may refer to: Places * Rouse, California, United States, a census-designated place * Rouse, Wisconsin, United States, an unincorporated community * Rouses Point, New York, United States, a village * Rouse Islands, Antarctica * Cape Rouse, A ...

of suspended sediment concentration with depth in a flowing fluid. The concentration of suspended sediment with depth goes as the power of the negative Rouse number. It also is used to determine how the particles will move in the fluid. The required Rouse numbers for transport as

bed load The term bed load or bedload describes particles in a flowing fluid (usually water) that are transported along the stream bed. Bed load is complementary to suspended load and wash load. Bed load moves by rolling, sliding, and/or saltating (hop ...

suspended load The suspended load of a flow of fluid, such as a river, is the portion of its sediment uplifted by the fluid's flow in the process of sediment transportation. It is kept suspended by the fluid's turbulence. The suspended load generally consists ...

, and

wash load Wash load is similar to a suspended load, but wash load sediment never interacts with the bed load. All of the sediment in the wash load stays suspended in the water throughout the channel (this concept has been debated). Wash load refers to a rive ...

, are given below.

References

* Whipple, K. X (2004), 12.163 Course Notes, MIT Open Courseware

{{DEFAULTSORT:Rouse Number Dimensionless numbers Fluid dynamics Sedimentology

See also

References