Adjustment of Friction in Hydraulic Models of Lakes

For complete dynamic similarity between a hydraulic model of a lake or closed basin and its prototype, both the Froude number and the Proudman number must be equal in the model and the prototype. For turbulent flow the Proudman number can not be explicitly determined and adjustment of model friction may be required. A method for adjustment of model friction is described which requires comparison of the damping of a standing long wave (or seiche) in the prototype and in the model basin. Assuming that the model frictional resistance could be decomposed into smooth boundary resistance and the resistance due to the addition of roughness elements, a mathematical formulation was developed for use in predicting the decay modulus for a roughened model basin. Good agreement was found between the analytical predictions and experimental results.