Related Experiment Video
Updated: Nov 27, 2025

Experimental Investigation of Secondary Flow Structures Downstream of a Model Type IV Stent Failure in a 180° Curved Artery Test Section
Published on: July 19, 2016
Entropy Wake Law for Streamwise Velocity Profiles in Smooth Rectangular Open Channels
Domenica Mirauda1, Maria Grazia Russo2
1School of Engineering, Basilicata University, Viale dell'Ateneo Lucano 10, 85100 Potenza, Italy.
Abstract:
In narrow open channels, the three-dimensional nature of the flow and the transport momentum from the sidewalls to the central region cause the maximum longitudinal velocity to occur below the water surface. The entropy model is unable to accurately describe the velocities near the free surface when the dip phenomenon exists. The present paper proposes a new dip-modified entropy law for steady open channel flows, which consists of three additional terms: the first one similar to Coles' function; the second one linearly proportional to the logarithmic distance from the free surface; and the third one depending on the cubic correction near the maximum velocity. The validity of the new model was tested on a set of laboratory measurements carried out in a straight rectangular flume with smooth boundaries and for different values of water discharge, bottom slope, and aspect ratio. A detailed error analysis showed good agreement with the data measured through the present research and a more accurate prediction of the velocity-dip-position compared with the one evaluated through the original entropy model. In addition, the modified entropy wake law matched very well with other literature data collected in rectangular cross-sections with different flow conditions.
Related Concept Videos
Bernoulli's Equation for Flow Along a Streamline
Bernoulli's Equation for Flow Normal to a Streamline
The pressure difference depends on the fluid's velocity and radius of curvature. The pressure variation is minimal in flows with nearly straight streamlines. However, the...
Uniform Depth Channel Flow
Steady, Laminar Flow in Circular Tubes
Steady, Laminar Flow Between Parallel Plates
Stream Function

