François Monnoyer

3D numerical design of tunnel hood

Abstract This paper relates to the parametric study of tunnel hoods in order to reduce the shape, i.e. the temporal gradient, of the pressure wave generated by the entry of a High speed train in tunnel. This is achieved by using an in-house three-dimensional numerical solver which solves the Eulerian equations on a Cartesian and unstructured mesh. The efficiency of the numerical methodology is demonstrated through comparisons with both experimental data and empirical formula. For the tunnel hood design, three parameters, that can influence the wave shape, are considered: the shape, the section and the length of the hood. The numerical results show, (i) that a constant section hood is the most efficient shape when compared to progressive (elliptic or conical) section hoods, (ii) an optimal ratio between hood’s section and tunnel section where the temporal gradient of the pressure wave can be reduced by half, (iii) a significant efficiency of the hood’s length in the range of 2–8 times the length of the train nose. Finally the influence of the train’s speed is investigated and results point out that the optimum section is slightly modified by the train’s speed.

Self-Organizing Hybrid Cartesian Grid Generation and Application to External and Internal Flow Problems

An automatic adaptive hybrid Cartesian grid generation and simulation system is presented together with applications. The primary computational grid is an octree Cartesian grid. A quasi-prismatic grid may be added for resolving the boundary layer region of viscous flow around the solid body. For external flow simulations the flow solver TAU from the “Deutsche Zentrum fur Luft- und Raumfahrt (DLR)” is integrated in the simulation system. Coarse grids are generated automatically, which are required by the multilevel method. As an application to an internal problem the thermal and dynamic modeling of a subway station is presented.