Large-scale parallel and grid computing for turbulence and biomechanics problems Steven Dong, Division of Applied Mathematics, Brown University Solution of grand-challenge problems in physical and biological sciences such as direct numerical simulation (DNS) of drag crisis in bluff-body flows and modeling blood flow in the entire human arterial tree requires very-large-scale parallel and grid computing due to the enormous problem sizes. The key question facing computational scientists is how to devise efficient algorithms to exploit the power of supercomputing and the essentially unlimited scalability of the computational grids such as the TeraGrid. In this talk I will discuss multilevel-type parallel paradigms within the spectral element framework that can take advantage of the hierarchical structures arising from the physical problems and computations as well as those in the architectures of supercomputers and computational grids. These algorithms have enabled simulations of turbulence and biomechanics problems with hundreds of millions of degrees of freedom. I will specifically look into the DNS of turbulent bluff-body flows at Reynolds number Re=10000 and the simulation of blood flow in the human arterial tree on the TeraGrid.