Energy loss coefficient for reflection of waves from vertical slit

Abstract

Accuracies of the existing formulae for the reflection coefficient of waves due to perforated wall are checked based on the result of hydraulic experiments conducted for vertical slit perforated walls with various thicknesses. Extensive numerical experiments are also performed using a CFD code to investigate the energy dissipation due to perforated walls for various wall-thicknesses and flow conditions. A new empirical formula for energy loss coefficient considering the effect of the thickness of perforated wall is obtained based on the results of computational experiments. It is found that the energy loss coefficient decreases as the wall-thickness increases and the maximum reduction of energy loss coefficient reaches up to 40% of the value calculated using the conventional formula for the sharp-crested orifice. To check the validity of the new formula the reflection coefficient of waves due to perforated wall is evaluated and compared with the results of existing theories and hydraulic experiments.