Understanding aerodynamics around bluff bodies, particularly bridges, is one of the crucial pillars of civil engineering research. The high turbulence winds which the bridge is constantly subjected to continuously induce stress on the structure, and affect the ongoing traffic due to the interaction with tall bridge towers. This work seeks to investigate the flow structure of high turbulence intensity, using the CFD library OpenFOAM. 2D RANS and 3D LES models are studied, comparing different levels of turbulence intensity. This joint work between the School of Civil Engineering and School of the School of Mathematics and Statistics compares a variety of turbulence velocity generators, highlighting the utility of Random Flow Generators.
One of the most intriguing topics in mathematical fluid dynamics is whether the finite-time singularity emerges on the solution of the 3D Euler equation. Gibbon's model for embodying the vortex-tube paradigm of turbulence has been proven to have singular solutions of 3D Euler fluid. In this research, the 3D Euler fluid is bounded by a cylinder without lid, whose velocity field is given according to the Gibbon's model and the rotational symmetry is imposed. The Lagrangian solutions of the velocity and pathline are given analytically, as well as the singularity time. We find in the solution that the fluid behaves with singularity that all the particles at the blowup point concentrate on a point or a ring with a width of 0. The asymptotic behavior of the fluid near the singularity time is investigated, in which we find that the existence of the singularity depends on the power-function approximation of the initial stretching rate of vorticity in the vicinity of the blowup point.