Numerical simulation of fuel filling with volume of fluid

The design of a new filling pipe and tank is often expensive and time consuming. The filling pipe is often costume made and if smaller changes are done in the geometry, a new filling pipe must be produced. It is therefore of interest of doing the preliminary investigation of a new fuel filling pipe with Computational Fluid Dynamics (CFD). The volume of fluid is an interface tracking method used for multiphase flow. The interface between gasoline and air is tracked by a color function and the interface is reconstructed in an implicit or explicit way. For the turbulence modeling Realizable k-ε with standard wall function is used. The experiments planned for verification of the numerical simulations failed. The transparent tank used for the experiments reacted with the gasoline and the filling pipe started to burst. Therefore the objective of the master thesis is changed from trying to develop a method for predicting fuel filling to a parameter study of the important parameters for modeling fuel filling. The important parameters are the mesh and time step size The different meshes investigated during this project are a tet mesh, different prism meshes and a hex mesh. All the prism meshes created for the project showed similar or better result in simulation of fuel filling than the tet mesh. Due to lack of time, the hex mesh is not fully investigated. The time step tested during the project was 2es, 5es and 2.5es. The time step 2es is proven to be too large for all the tested cases. Comparison between the other two time steps, 5es and 2.5es, showed little difference. The simulations indicate that it is possible to simulate fuel filling with volume of fluid. The implicit VOF discretization method is much more stable than the explicit VOF, and the implicit VOF is recommended as discretization method. The most promising mesh during the project is the fine 17 layers prism mesh with the time step 5es. Acknowledgments This thesis has been done at the CFD group at Volvo Car Corporation, Gothenburg. I would like to thank my supervisors at Volvo, Frida Nordin and Dr. Torbjörn Virdung for their patience and support during these months of hard work. I would also like to thank Patrik Sondell for improving my stamina, Marina Olsson for stepping in when my supervisors was away and the other guys at the CFD group for all the great time at the "fika" table. I would also like to thank Professor Bengt Andersson at Chalmers University of Technology for his support during this project and for that he has woken my interest for CFD. Most of all I would like to thank my future wife for her love, support and understanding. I am really looking forward to our marriage! Kristoffer Johansson Gothenburg, Sweden May 30, 2011