Numerical modelling of Trawl Net considering fluid-structure interaction based on Hybrid Volume Method

Abstract

Trawl nets are mostly flexible structures working in the water. In order to investigate the effect of the fluid-structure interaction on the trawl net’s numerical model, we modeled the trawl net and the flow field based on lumped mass method and finite volume method, separately; then we adopted a hybrid volume method (HVM) to model the fluid-structure interaction between the net and surrounding water. Since the gridding of trawl net is independent of its shape within the proposed HVM, large mesh can be used for the calculation of fluid-structure coupling model for higher efficiency. First, existing flume tank experimental data were used to verify the accuracy of the HVM. Then, trawl net states were analyzed based on the HVM by taking the fluid-structure coupling into consideration. The simulation reveals that difference between the trawl net model with and without fluid-structure interaction is about 6%, the main reason for that is the relative velocity of water flow around the codend is only 1/5 of the towing speed because of the flow blocking by the trawl mesh upstream. The above results indicate that fluid-structure interaction is very important for the analysis of trawl net which should not be ignored when numerical modelling.