Impact Analysis of Riblets on Drag Resistance of a Semi-Submerged Plate Using CFD

Abstract

In this research, CFD technique was used to reduce the resistance of a partially submerged plate by using the so-called shark skin technique, which is based on the principle of having regular channels on the surface of the plate in order to regulate the flow and reduce the disturbances in the crossflow on the surface of the plate, which results in reducing the transverse friction stresses, which leads to reducing the resistance. The URANS (Unsteady Reynolds Averaged Navier Stocks) method and the k-ꞷ SST turbulence model were used to solve the flow regulating equations available in the Ansys program. Many cases were tested. In the first stage, the efficiency of the grid and the numerical settings were validated by comparing their results with the available experimental results. Then, sets of channels were added to the upper part of the submerged section of the plate, and in the final step, channels were added to the all-submerged part. The calculations were performed at two values of velocity 2.0 and 3.85 m/s. The resistance and crossflow on the plate surface were calculated for all the studied cases. The best resistance reduction was obtained with the case of the channels over the all-submerged body and the velocity of 3.85 m/s where the resistance reduction reached 3.75%.