Computation of interactions of blast with responding solids using an "embedded solid" approach

by 1974- Liew, Yih-Pin

This thesis describes the development of a Computational Fluid Dynamic (CFD) methodology and its implementation to simulate a shock/blast wave interaction with a complex structure, to a good engineering approximation. The method allows for an easy definition of the geometry of the structure and helps to reduce the computational resource requirements. An ‘embedded solid’ approach, using the Brinkman Penalization Method, is used for its ease of defining a structure in the computational domain. Two implementations of the Brinkman Penalization Method are considered: a semi-implicit computation of the Brinkman Formulation and a discrete-time derivative version of the Formulation. It is found that these two implementations give essentially the same results, though they give slightly different solutions compared to the exact solutions. The semi-implicit method is more expensive computationally. A distorting grid methodology is used to simulate the movement of the ‘embedded solid’ to avoid the disturbance in the simulation that results when the ‘solid’ moves across a new grid point. The distorting grid methodology allows the ‘solid’ to stay in the same computational grid while moving in the physical domain. Several test cases are presented in this thesis to demonstrate the method’s ability to simulate complex structures easily. These include, two-dimensional cases of shock waves over a square cavity and shock wave interaction with an I-beam. For a three-dimensional case, low Mach number flow past a cone is presented. For the responding geometry cases, a simulation of a three degree of freedom cylinder responding to a shock wave is presented. The above test cases shows that the methodology can simulate complex structures in high Mach number and shock strength flow, and the structures corresponding response to the flow. iii