Characteristics of Submerged Flow Below Gate With Sill in Non-Prismatic Channels
The characteristics of submerged flow below vertical gate with sill upstream of horizontal diverging channel reach are analyzed based on experimental investigation. The experimental program is conducted in a laboratory flume with 10 cm wide, 31 cm deep and 3.0 m long. A diverging channel reach with fixed length and constant divergence angle is used. Polygonal sills with constant height, constant upstream slope and variable downstream slope are used under the gate. These sills are tested under wide range of similar submerged flow conditions to investigate the effect of sill slope on the flow characteristics. Also, a particular sill is tested under different heights to address the effect of sill height on the flow characteristics. Both the effects of submergence and the under-gate Froude number on the flow below the gate are discussed. Different flow regimes are considered (Supercritical, critical and subcritical flow). It is found that the presence of sill under the gate upstream of diverging channel reach has a remarkable effect on the discharge coefficient of the gate. It is noticed that the submergence ratio and the upstream head ratio are not able to explain the observed variations (or scatter of data) in the discharge coefficients. These variations or scatters are completely explained by the under-gate Froude number and the differential head ratio.
Sluice‐Gate Discharge Equations
Sluice‐gate discharge coefficient is an involved function of geometric and hydraulic parameters. For free flow, it is related to upstream depth and gate opening, whereas for submerged flow, in addition to these parameters, it depends on tail‐water depth. The present practice of discharge coefficient determination is from curves drawn relating discharge coefficient and upstream‐depth gate‐opening ratio with tail‐water‐depth gate‐opening ratio being the third parameter for submerged flow. This method lends itself to sufficient error of judgment due to interpolation between two types of curves. Furthermore, the graphical information cannot be used for any analytical and/or numerical method for flow control and flow profile determination. In this paper high‐accuracy discharge coefficient equations for free and submerged flows have been developed along with the criterion for determination of free and submerged flow. Procedures for solution of various gate‐opening problems have also been given.
Investigations of dielectric gratings using electrodynamic models based on volume integral equations
Eigenmodes of planar and cylindrical dielectric gratings (DGs) and electromagnetic wave scattering from multiplayer DGs are investigated. The DG characteristics are calculated using numerical-analytical solution of integral equations (IEs).