What causes supercritical flow?

What causes supercritical flow?

Critical flow is unstable and a small fluctuation in energy will shift the flow into supercritical or subcritical flow. Mild Slope is less than the critical slope and the normal depth is greater than critical depth (yn>yc). The flow is subcritical and controlled downstream.

Is supercritical flow bad?

Supercritical flow involves shallow water flowing in high velocity. Owing to swift flow of water in channels accommodating supercritical flow, there is considerable safety risk in the event of passengers falling into the channel and washed away to downstream.

How do you know if a flow is supercritical or subcritical?

If Fr is greater than 1.0, flow is supercritical; if it is under 1.0, flow is subcritical. Fr is 1.0 for critical flow conditions. 3. Critical Slope: Critical slope is that channel slope for a particular channel and discharge, at which the normal depth for uniform flow will be the same as the critical depth.

What is Froude number if flow is supercritical?

For sub-critical flow the depth is greater and the velocity lower, therefore the Froude number is always less than 1.0; for supercritical flow the opposite is true and the Froude number is always greater than 1.0.

How many types of GVF profiles exist?

The total number of possible types of GVF profiles are : 9.

What do you mean by supercritical flow?

A supercritical flow is a flow whose velocity is larger than the wave velocity. The analogous condition in gas dynamics is supersonic.

What is rapid varied flow?

Rapidly Varied Flow (RVF) is a significant change in water depth or velocity of flow over a short distance. Gradually Varied Flow (GVF) is the flow where the water depth changes gradually over a large distance. Hydraulic jump is an example of rapidly varied flow, where the liquid level rises suddenly.

What is the meaning of subcritical?

Definition of subcritical 1 : less or lower than critical in respect to a specified factor. 2a : of insufficient size to sustain a chain reaction a subcritical mass of fissionable material.

What is the significance of Froude number?

The Froude number is used to compare the wave making resistance between bodies of various sizes and shapes. In free-surface flow, the nature of the flow (supercritical or subcritical) depends upon whether the Froude number is greater than or less than unity.

Why is the Froude number important?

The Froude Number is a dimensionless parameter measuring the ratio of “the inertia force on a element of fluid to the weight of the fluid element” – the inertial force divided by gravitational force. The Froude Number is important when analyzing flow in spillways, weirs, channel flows, rivers and in ship design.