Implementation and testing of a time dependent acceleration model for the numerical simulation of sloshing

Kurzfassung

Within the course of this thesis, a time dependent acceleration source term model was implemented in the DLR TAU (THETA) code. This contributes to a better understanding of the undesired yet unavoidable dynamics of liquid propellants in tanks of spacecraft vehicles. The objective is to carry out a simulation of a time dependent acceleration in influencing a liquid propellant by implementing a suitable varying acceleration model into the momentum equation. For the applications of present interest the acceleration must be interpolated from data to be obtained from an external ASCII �le. Before the �nal test case, the basic functionality and stability of the code is tested with two and three dimensional test cases. For these test cases the time dependant acceleration is hard-coded in the source code to simplify the infrastructure and reduce error sources. In each test case the numerical errors are determined using di�erent grid resolutions. For an accurate interpolation of the acceleration for a varying time step the linear, barycentric Lagrange and Akima interpolation method are selected and tested. The Akima interpolation method proves to be most suitable for the required acceleration model. The accuracy of the model is validated using experimental sloshing results which are based on a lateral excited cylindrical tank. Finally a comparison of the numerical and experimental sloshing results conveyed that the newly implemented Akima acceleration model in combination with the two phase flow methodology implemented by Gauer [20] delivers accurate results.