In this paper,a novel adaptive mesh σ coordinate model is proposed for the studies of Wave and Structure Interaction (WSI).The model is validated by using the case of a solitary wave movement in an open channel with constant water depth and the case of nonbreaking solitary wave propagating over a step.Numerical results agree well with the analytical solutions obtained based on the Boussinesq theory,the laboratory data and other numerical model results.The proposed model is then used to study a solitary wave interacting with a suspended fixed structure.